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By J. P. Denny

The constitution of the Ga-In system was determined by thermal methods. An experimentally determined metastable equilibrium line (an extension of the indium-rich liquidus) was obtained. The various alloys were studied metallographically using polished samples obtained by a casting method. These low melting alloys required a special dry-ice assembly to maintain a suitable temperature. RECENT interest in alloys that are liquid at room temperature has led to rather extensive investigation of gallium-base alloys. Widely distributed over the earth, gallium could be produced in substantially larger quantities than at present, if a significant demand existed.' One study' has established its presence in 12 out of 14 zinc blends, in all of 15 aluminum ores, in 4 out of 12 manganese ores, in 35 out of 91 iron ores, and in all of 7 magnetite ores. It occurs as a rule in minute amounts, however, leading to high extraction costs. Recent quotations run from $2.50 to $7.50 per g. During the course of the present investigation, portions of the system Ga-In have been redeter-mined, and the results of this study are presented herein. Thermal and metallographic methods have been employed. Lecoq de Boisbaudran, the discoverer of gallium, conducted the first investigation" on Ga-In alloys in 1885. The temperatures of incipient melting, and of completion of melting, were determined at four alloy compositions. In 1936, Hansen' constructed a eutec-tic-type phase diagram for the system Ga-In, based on . work. The existence of a Ga-In compound was regarded as improbable by Hansen, and subsequent investigations are in agreement. French, Saunders, and Ingle3 conducted a more complete study of the system in 1938, using thermal methods. Their phase diagram is a eutectic type, containing a unique concave-upward liquidus. The solid-solution range of gallium in indium was reported as 9.5 pct by weight, and that of indium as less than 1 pct, at the eutectic temperature. The eutectic composition, determined as being bracketed by the compositions showing a true horizontal at the eutectic temperature (16°C), was reported as 76 5-0.5 pct Ga and 24 i 0.5 pct In. Experimental Procedure The preparation of Ga-In alloys is simplified by the low melting points involved. Various compositions were prepared by melting in pyrex tubes, using a cover of distilled water or parafin to prevent the alloys from wetting the glass wall. In all cases, the melts were homogenized. by stirring. Where possible, both cooling and melting curves were determined. The extensive undercooling of gallium was found to prohibit a satisfactory cooling-curve analysis of gallium-rich alloys, however, and transition points on the gallium side of the eutectic could be determined only by melting curves. The inverse rate method of thermal analysis proved to be most satisfactory and was used to a great extent. Various heating and cooling rates were used, ranging from 0.2" to 5.0°C per min. Low temperature melting analyses were conducted within a constant temperature bath, maintained at about 70 °C. The alloys were solidified (under water or paraffin) within a pyrex tube, using dry ice; the tube was then sealed within a cold Dewar flask, the unit transferred into the constant temperature bath, and periodic temperature readings taken. The high temperature melting-curve determinations and all cooling-curve determinations were made in a vertical tube furnace. At near-eutectic compositions, the furnace was placed within a refrigerated room held at —20°C. Accordingly, the furnace on cooling approached —20°C asymptotically and permitted the determination of those phase transitions occurring below room temperatures. Temperatures were measured with a 30-gage iron-constantan thermocouple, immersed directly in the alloy. To prevent contamination of the melt, the leads and junction were coated with Lucite, applied by painting with a solution of Lucite in ethylene dichloride. Electromotive force measurements were made with a Leeds and Northrup precision potentiometer, type 8662. The couples were calibrated against the boiling point. of water and, at lower temperatures, against a calorimeter thermometer having a Bureau of Standards certificate. The melting points of gallium and indium used in the present investigation were determined as 29.-77° and 156.1°C, in good agreement with previously reported values of 29.78°C° and 156.4"C.' The spec-

Jan 1, 1953

By T. Seldenrath

In the development of a fluid -operated hammer drill' for accelerated penetration of hard rock formations in oil wells, a research investigation was conducted to evaluate the percussion effects obtained with different design characteristics and to determine the possibilities of percussion in the low frequency range. Tests were conducted on granite blocks and comparable impact forces were measured with a load cell under selected test conditions. These full-scale laboratory tests provided an evaluation of the effectiveness of percussion which was further supported by actual downhole field performance. While much pertinent data have been presented by other investigators the method of evaluation described in this article resulted in good correlation between laboratory and field performance and may be applicable in other low frequency percussion developments. EXPERIMENTAL METHOD For these tests the bit was held stationary and the test block was rotated and forced upward against the bit by a hydraulically-lifted rotary table. "Weight on bit" was calculated from pressure readings on the fluid system of the lifting cylinders—corrected for tare and friction. Percussion was obtained with several tubular hammers of different weights up to 320 lb. These were lifted mechanically and allowed to drop by gravity from various heights onto a slidably-mounted bit sub or "floating anvil" for calibration of the load cell response with known kinetic energy of the hammers. During evaluation of percussion effects, the hammers were hydraulically operated to provide a range of percussion frequencies up to 1,020 blows per minute delivered to the anvil. To obtain comparable test readings, the load cell of the strain gauge type, was attached to the bottom of the anvil or bit sub in place of the bit. The load cell rested on a typical granite test block mounted on the drilling table. The latter was hydraulically supported as in the actual drilling operation. The effect of support resistance was the same for all tools when calibrating. Impact forces so determined werethusdirectly comparable with one another for the purposes of this investigation. When a roller bit was substituted for the load cell for actual drilling, the impact force would probably be reduced due to the resiliency of the bit body, legs. cones and teeth and the penetration of the teeth into the rock. However, since the bits and rock specimens were uniform in these tests, an evaluation of actual tool performance, in terms of parameters previously determined with the load cell at the selected standard conditions of calibration, proved satisfactory. Throughout these tests, 8¾-in. standard tricone, hard rock toothed roller bits and carbide-insert roller bits were used. Rotary speeds were 50 and 100 rpm; static weight on bit was applied up to 40,000 Ib, and percussion frequencies up to 1,020 blows per minute were available. During this investigation it was found that toothed bits on which the teeth had developed flat ends about 3/16 in. wide did not change appreciably for the duration of a test. Hence, all toothed bits used in this study were in this condition. Conventional reference curves obtained in these tests show that increasing weight on hit by 2:1 yielded an increased penetration rate of approximately 2.7:1, while an increase in rotary speed of 2:1 netted an increased penetration rate of roughly 1.7:l. Results are thus of the same order as those reported for hard rock drilling by other investigators." CALIBRATION Under the selected standard test conditions previously described, with the lifting table hydraulically supported, and the anvil interposed between hammer and load cell, the hammers were dropped from known heights. Thus, with the kinetic energy of the hammer known, the corresponding maximum impact force shown by the cell was determined. (It may be of passing interest to note here that special drop tests with the hammers showed that no appreciable reduction in impact force resulted from introduction of the anvil or hit sub.) From these calibrations, it was possible to determine the theoretical kinetic energy available in the hammer from the maximum impact force shown by the load cell while operat-

By J. E. Andersen, J. Halpern, C. S. Samis

In the presence of oxygen, galena is oxidized in an aqueous medium containing sodium hydroxide, in accordance with the following reaction: PbS + 2O2 + 3OH ? HPbO2 + SO4 = + H2O A novel method was devised for following this reaction which takes place in an autoclave under oxygen pressure, by measuring the concentration of HPbO2- in the solution with a cathode ray polarograph employing stationary platinum electrodes. Using this procedure a study was made of the kinetics of the reaction, in which the effect of a number of variables, including temperature, oxygen pressure, NaOH concentration, and agitation, on the rate, were determined. The results of this study are described and discussed, in terms of possible mechanisms for the reaction. IT is known that sulphide minerals can be oxidized in aqueous media in the presence of oxygen under pressure. Reactions of this type can be classified in two categories depending upon whether the products of oxidation are insoluble or soluble in the aqueous medium. An example of the first type of reaction is the oxidation of pyrite in alkaline solutions, giving rise to an insoluble iron oxide. The kinetics of this reaction have been investigated and its mechanism established.' It has been applied in the oxidation of iron sulphides present in refractory gold ores to improve the subsequent recovery of gold by cyanida-tion.' The second type of reaction finds application where it is desired to recover the metal by leaching during oxidation. In this case a medium is selected in which the oxidized mineral is soluble. For example, nickel, copper, and cobalt sulphide ores can be treated by oxidation in the presence of a solution of ammonia dissolving the nickel, copper, and cobalt as the metal ammine sulphate salts.:' A similar treatment has also been reported to apply to zinc sulphide ores.' It is known that lead sulphate is soluble in solutions of sodium hydroxide or ammonium acetate. It should therefore be possible to dissolve the lead from galena ores by aqueous oxidation with oxygen under pressure using either of these solutions. The applicability of the ammonium acetate treatment has been investigated and confirmed in a recent study.' The present paper describes the results of a similar study in which the kinetics of the oxidation of galena in sodium hydroxide solutions have been investigated. The object of this investigation was pri- marily to obtain information of a fundamental nature relating to the kinetics and mechanism of this reaction. The use of pulps of comminuted ore in a study of this type is undesirable because of the difficulty in controlling and measuring the surface area. The measurements were therefore made using galena crystals of measured surface area and in this way absolute reaction rates were obtained. The reaction was found to proceed as follows: PbS + 2O2 + 3OH ? HPbO2 + SO4 + H2O [I] The products are sodium plumbite and sodium sulphate salts which dissolve in the aqueous solution. The reaction studies were carried out in an autoclave in which a desired pressure of oxygen was maintained. The reaction was followed by measuring the concentration of lead in the solution with a cathode ray polarograph. The results obtained in this investigation are presented and discussed in the present paper. Experimental Materials: The crystals of galena were obtained from Violamac Mines, Sandon, B. C. The following impurities were indicated by spectrographic analysis carried out by the Provincial Assay Office, Victoria, B. C.: Sn, 0.02 to 0.2 pct; Sb, 0.07 to 0.7; Zn, 0.01 to 0.1; Si, Fe, Mg, As, less than 0.05 pct; Ag, 126 oz per ton, the latter determined by standard fire-assaying procedure. After cutting a specimen measuring approximately 5x7x12 mm, the crystal surfaces were ground parallel to the 100 axes using No. 2 emery, washed with water, and the dimensions were measured with a micrometer. Oxygen gas was of commercial grade and supplied in cylinders by Canadian Liquid Air. Solutions were made up with chemicals of chemically pure grade and distilled water. Equipment: Autoclave: The autoclave used in these studies was constructed of stainless steel and

Jan 1, 1954

By Fred H. Poettmann

The vaporization characteristics of carbon dioxide in a League City natural gas - Billings crude oil system were studied at three temperatures, 38°. 120°, and 202°F and for pressures ranging from 600 to 8,500 psi. Variation of carbon dioxide concentration up to 12 mole per cent in the composite showed no effect on the equilibrium vaporization ratios (K values) of the hydrocarbon constituents or on the K value of carbon dioxide itself. It was shown that carbon dioxide is more soluble in crudes than in distillates which is contrary to the behavior of methane. A working chart of carbon dioxide K values is presented. INTRODUCTION The study of the equilibrium vaporization ratios of mixtures of paraffin hydrocarbons has been rather thorough.2,6,7,8,9 In the past few years considerable attention has been paid to the vaporization characteristics of the so-called noncondensable gases such as nitrogen, carbon dioxide, and hydrogen sulfide in mixtures of hydrocarbons. since they usually occur to some extent in most crude oils and natural gases.1,3,4,5 Knowledge of this behavior is useful to both the production and refining phases of the petroleum industry. This paper reports the equilibrium vaporization ratios (K's) of carbon dioxide in a mixture of League City natural gas and Billings crude oil, and compares them to those obtained in a natural gas-distillate system. The equilibrium vaporization ratios for the hydrocarbon components in this system had previously been studied by Roland.' In addition to the determination of the K values for carbon dioxide, the K values for methane and ethane were also determined in order to observe what effect, if any, the presence of carbon dioxide had on these K values. The concentration of carbon dioxide was also varied in order to observe the effect of this variable on the carbon dioxide K values. EXPERIMENTAL PROCEDURE The apparatus used in this study cotlsisted of a stainless steel equilibrium cell of about 2 liters capacity. The cell was mounted on trunions permitting rocking in a thermostatically controlled oil bath. Two high pressure valves fitted with steel tubing were mounted on the top of the cell. one was used for sampling the equilibrium gas phase and the other for sampling the equilibrium liquid phase by means of an induction tube within the cell. Stainless steel tubing from the bottom of the cell led to a mercury reservoir and manifold which was connected to a free-piston type pressure gauge manufac- lured by the American Instrunlent Ctr. and to a volumetric. putrip. The temperature of the oil bath was measured by means of a ralibrated mercury-in-glass thermometer. The recorded temperatures are believed to be accurate to ±0.5 °F. The pressures are correct to 22 psi. The crude oil used in this study was stock tank oil obtained from the Wilcox formation in the Billings Field, Noble County. Okla. The natural gas was obtained from the League City Field. Galveston County, Tex. The oil was treated with anhydrous calcium sulfate in order to remove the last traces of water. To insure a supply of constant composition gas at room temperature the cylinders of League City gas were cooled to about 30°F, inverted, and the condensed liquid was allowed to drain from the cylinders. The analysis of the gas and crude are tabulated in Table I. The carbon dioxide came from Pure Carbonic, Inc., and was .stated to have a purity of 99.5 per cent or better. The procedure used to obtain samples of the equilibrium liquid and vapor was similar to that employed by others making use of the rocking type equilibrium cell.6,7,8 The equilibrium cell was evacuated and calculated quantities of carbon dioxide, natural gas, and crude oil were charged to the cell to the desired pressure. In charging the equilibrium cell an attempt was made to maintain the ratio of the natural gas to crude oil as close as possible to that employed by Roland. After the cell was charged, samples of

Jan 1, 1951

By Fred H. Poettmann

The vaporization characteristics of carbon dioxide in a League City natural gas - Billings crude oil system were studied at three temperatures, 38°. 120°, and 202°F and for pressures ranging from 600 to 8,500 psi. Variation of carbon dioxide concentration up to 12 mole per cent in the composite showed no effect on the equilibrium vaporization ratios (K values) of the hydrocarbon constituents or on the K value of carbon dioxide itself. It was shown that carbon dioxide is more soluble in crudes than in distillates which is contrary to the behavior of methane. A working chart of carbon dioxide K values is presented. INTRODUCTION The study of the equilibrium vaporization ratios of mixtures of paraffin hydrocarbons has been rather thorough.2,6,7,8,9 In the past few years considerable attention has been paid to the vaporization characteristics of the so-called noncondensable gases such as nitrogen, carbon dioxide, and hydrogen sulfide in mixtures of hydrocarbons. since they usually occur to some extent in most crude oils and natural gases.1,3,4,5 Knowledge of this behavior is useful to both the production and refining phases of the petroleum industry. This paper reports the equilibrium vaporization ratios (K's) of carbon dioxide in a mixture of League City natural gas and Billings crude oil, and compares them to those obtained in a natural gas-distillate system. The equilibrium vaporization ratios for the hydrocarbon components in this system had previously been studied by Roland.' In addition to the determination of the K values for carbon dioxide, the K values for methane and ethane were also determined in order to observe what effect, if any, the presence of carbon dioxide had on these K values. The concentration of carbon dioxide was also varied in order to observe the effect of this variable on the carbon dioxide K values. EXPERIMENTAL PROCEDURE The apparatus used in this study cotlsisted of a stainless steel equilibrium cell of about 2 liters capacity. The cell was mounted on trunions permitting rocking in a thermostatically controlled oil bath. Two high pressure valves fitted with steel tubing were mounted on the top of the cell. one was used for sampling the equilibrium gas phase and the other for sampling the equilibrium liquid phase by means of an induction tube within the cell. Stainless steel tubing from the bottom of the cell led to a mercury reservoir and manifold which was connected to a free-piston type pressure gauge manufac- lured by the American Instrunlent Ctr. and to a volumetric. putrip. The temperature of the oil bath was measured by means of a ralibrated mercury-in-glass thermometer. The recorded temperatures are believed to be accurate to ±0.5 °F. The pressures are correct to 22 psi. The crude oil used in this study was stock tank oil obtained from the Wilcox formation in the Billings Field, Noble County. Okla. The natural gas was obtained from the League City Field. Galveston County, Tex. The oil was treated with anhydrous calcium sulfate in order to remove the last traces of water. To insure a supply of constant composition gas at room temperature the cylinders of League City gas were cooled to about 30°F, inverted, and the condensed liquid was allowed to drain from the cylinders. The analysis of the gas and crude are tabulated in Table I. The carbon dioxide came from Pure Carbonic, Inc., and was .stated to have a purity of 99.5 per cent or better. The procedure used to obtain samples of the equilibrium liquid and vapor was similar to that employed by others making use of the rocking type equilibrium cell.6,7,8 The equilibrium cell was evacuated and calculated quantities of carbon dioxide, natural gas, and crude oil were charged to the cell to the desired pressure. In charging the equilibrium cell an attempt was made to maintain the ratio of the natural gas to crude oil as close as possible to that employed by Roland. After the cell was charged, samples of

Jan 1, 1951

By R. J. P. Lyon, A. E. Prelat, H. Lawrence

Introduction In 1977, the US Bureau of Mines awarded a grant to the state of South Carolina to explore the possibility of using Landsat multispectral scanner (MSS) data as an aid in monitoring surface mining activities in selected counties of the state. Work had been done in Aiken County prior to the grant by USBM and state personnel at the EROS Data Center using both the GE Image 100 and ESL IDIMS systems. The initial work on the 1:100 consisted of locating and measuring the areas of various kaolin mines. The results were excellent on location, identification, and accurate area measurements of several mines as compared with aerial photos of each mine. The effort also included locating and measuring the size of all mines (including sand and gravel) within two US Geological Survey (USGS) 7 % - min quadrangle maps. Line printer overlays using the IDIMS equipment and software resulted in the location of all known mines within an estimated error less than zt 91.4 m. Mine acreage was calculated by counting each symbol (which represented one pixel) and multiplying by 1.1 (the number of acres per pixel). [Fig. 1] shows a portion of one quadrangle overlay. [Table 1] gives a comparison of acreage measured for several mines from the 1-100 and IDIMS system vs. aerial photo measurements. The success of the preliminary work resulted in the South Carolina Land Resources Conservation Commission submitting a proposal to USBM for funding to expand the scope of work to other mineral mining operations within the state and determine if Landsat Imagery could be used to accurately locate and measure mining and reclamation activity on a continuing basis. Three separate tasks were proposed for selected kaolin mines in Aiken County: Task 1, to measure changes in active mine developments over the period 1974-77; Task 2, to measure reclamation activity, and, if time permitted, seasonal changes in mine signatures over the same period of time; and Task 3, to classify one complete mining operation (i.e., differentiate between active, spoil, overburden, water, reclaimed portions and surrounding terrain. The major effort was centered around J.M. Hubeis Richardson mine. Mining operations were progressing in a northerly direction and included three areas of reclamation: one prior to 1974; one started during early 1974; and one reclaimed during 1976. A discussion of all work done under the grant is available in the March 1979 Final Report listed under References. Computer compatible tapes (CCTs) containing MSS data from Landsat Path 18, Row 37, were purchased from the National Aeronautics and Space Administration (NASA) covering the period February 1974 through January 1977. The MSS data were processed on the General Electric Image 100 using parallelepiped classification at the EROS Data Center's Data Analysis Laboratory, Sioux Falls, SD, and at the Stanford Remote Sensing Laboratory, Stanford University, Palo Alto, CA, utilizing both an unsupervised classification (ISOMIX) and a supervised classification (sequential discriminant analysis). Studies at Stanford University Remote Sensing Lab (SRSL). In Feburary 1977, initial work was begun at Stanford using the STANSORT computer program running on a DEC PDP-10 (Honey, Prelat, and Lyon, 1974). This software is fully interactive and designed to study Landsat CCT data at high resolution (small areas) on a pixel-by-pixel basis (Lyon, 1977). Unsupervised Classification. The initial step was to locate the Richardson mine on the positive print of the full Landsat scene from CCT 1644-15252, dated 6/17/74. This was relatively easy due to a large abandoned kaolin mine and a long narrow pond clearly visible in the scene. Two unsupervised classifications of the Richardson mine were run using ISOMIX clustering (Honey, Prelat and Lyon, 1974). (ISOMIX essentially follows the interactive clustering procedures of ISOCLS Kan, Holley, and Parker. 1973). Although the classifications were successfully accomplished, it was apparent from the TV display that the results did not clearly define the mine areas. A supervised classification would have to be made in order to clearly separate each portion of the mine. Supervised Classification. This classification was done using the Stepwise Discriminant Program (BMDO7M) which is part of the BIOMED package (Dixon, 1970) and involved the following steps: Training group populations were selected and the digital

Jan 1, 1982

By R. R. Angel

Drilling rate is a parameter that should be considered in determining the volume requirements for air and gas drilling. The use of past methods which ignore the effects of the solids content upon the pressure and velocity of the annulus flow stream can result in undercalculation of the required volurne by as much as 50 per cent. A vertical-flow equation is presented for determining volume requirements. This equation includes the effect of the solids that are transported up the annulus in the flow stream by incorporating the drilling rate as one of the parameters. The effect of down-hole temperature on required circulation rates is also ana-lvzed. A simple approximate method of determining volume requirements is presented. This method is more accurate than the methods used in the past. Hole cleaning difficulties are analyzed for a recent air drilling job where past methods indicated that - excess air was being used. Sample curves of calculated boitom-hole pressures are presented for air and gas drilling in several hole sizes. INTRODUCTION In certain areas the use of air or natural gas as a circulating medium for drilling oil and gas wells is becoming a common practice. Large increases in penetration rate and bit life are achieved through the use of these media in preference to mud or water. Drilling rates as high as 90 ft/hr have been obtained in shales. The importance of maintaining adequate circulation rate is generally recognized; however, much disagreement exists among drilling operators as to what constitutes "adequate" circulation rate. In quarry drilling, where annular velocities can be accurately determined, an annular velocity of 3,000 ft/min of standard air is required for best results in rocks having approximately the same density as those commonly penetrated in drilling oil or gas wells'. Although this standard air velocity has proven satisfactory for quarry drilling, some oil and gas well drilling operators believe that an equivalent annular velocity of more than 4,000 ft/min is required; others believe that as little as 2,000 ft/min . is sufficient. Much of this disagreement results from determining the required circulation rates with methods which fail to incorporate the drilled solids in an equation which is applicable to vertical flow. Hughes Tool Co. Bulletins No. 23' and 23-A3 present data for determining circulation rates based on the Weymouth formula. These data do not include the drilling rate as a parameter and, therefore, neglect the effect of the solids being transported up the annulus. In spite of this apparent defect and the fact that the Weymouth formula is not applicable to vertical flow, the Hughes data have well served the drilling industry in many areas and are important and timely contributions to the science of air and gas drilling. The Hughes data purposely omit a correction for increasing down-hole temperature. At slow drilling rates this effectively compensates for the use of a formula which is not valid for vertical flow; however, volumes determined by the Hughes method are not sufficient to support rapid drilling rates at moderate and great depths. For example, Phillips Petroleum Co.'s Cauthorn "D" No. l in the Vinegarone field for Val Verde County, Tex., was air drilled from 1,500 to 9,300 ft using a compressor delivering 1,400 cu ft/min. The 8 3/4-in hole was drilled with 5-in. drill pipe, and drilling rates as high as 90 ft/hr were obtained between 7,000 and 9,300 ft. No water or caving hole was encountered. At 7,728 ft it was necessary to wash-out 60 ft of cuttings to reach bottom after a trip to change bits. At 8,130 ft a twist-off occurred and the drill col-lars were stuck in drill cuttings. These difficulties indicate that the 1,400 cu ft/min of air was not sufficient to keep the hole clean. Hughes data indicates that 1,180 cu ft/min is sufficient to produce an annular ve-

Jan 1, 1958

By N. S. Stoloff, R. C. Ku, R. G. Davies

The stress-strain behavior of Fe-Co and Fe- V alloys containing up to 25 pct solute have been studied in the temperature range 25° to - 196°C. The microyield stress is independent of temperature for all alloys studied, while the temperature dependence of the ordinary yield stress is large and comparable to that for unalloyed iron. An alloy-softening phenomenon is observed for many alloys relative to unalloyed iron, and appears to be a consequence of removal of inter-stitials from solution and their subsequent agglomeration. The ductile to brittle transition temperature is increased markedly by both cobalt and vanadium. Transmission electron microscopy observations reveal that cross slip and cell formation are restricted with increasing solute, which can account for many aspects of yielding and fracture behavior. IRON and other metals of bcc structure slip on many planes of the (111) zone at moderate and elevated temperatures, giving rise to wavy glide. At low temperatures, however, there is a tendency for slip to be restricted to planes of only one or two crystallographic types; in the case of Fe-Si alloys for example, (110) glide predominates, giving rise to planar slip bands."' Restriction of cross slip at low temperatures in iron has been linked by Brown and Ekvall3 to increased strain hardening in the preyield microstrain region, leading to an apparently large temperature dependence of the yield stress. Support for this view has been provided by Lawley and Gaigher4 from a transmission electron microscope study of molybdenum. They concluded that dislocations at lower temperatures, by virtue of their inability to change planes readily, are unable to interact and annihilate, leading to an increase in internal stress and work-hardening capacity. Restriction of cross slip at low temperatures has also been suggested to be an important factor in determining the ductile to brittle transition of single-phase solids, including metals of bcc structure.5 It is pertinent to note that most solute elements tend to raise the ductile to brittle transition temperature of poly crystalline ferrite,6,7 although in some cases, e.g., Fe-Cr7 and Fe-Al,8 the dilute alloys may actually yield at lower stresses than unalloyed iron. It appears, therefore, that solute elements may have an effect analogous to lowering the test temperature with regard to restricting cross glide. Such an effect has indeed been observed in the ionic alloy system KCl-KBr,9 in which bromine atoms, although causing little misfit and consequently little effect on the yield stress of KC1, have a pronounced effect in restricting wavy glide and inducing brittleness. The purpose of the present investigation was to determine the effects of selected solute atoms on the yield stress and fracture behavior of iron, and to elucidate in turn how the slip character was related to these properties. Since it is known that interstitial atoms exert a strong influence on the mechanical behavior of iron, the solute elements chosen for study were vanadium, which reacts strong with interstitials,10 and cobalt, which does not form highly stable interstitial compounds." EXPERIMENTAL PROCEDURE Four-pound ingots of each of the following alloys were vacuum-melted in zirconia crucibles: Fe-1, 5, 10, 25 at. pct Co, and Fe-1, 4, 10, 20 at. pct V. An ingot of unalloyed iron from the same original stock as that used for the alloy was remelted under similar conditions to eliminate variations in interstitial content arising from differing thermal histories. Chemical analyses of the iron, cobalt, and vanadium melt stock are listed in Table I. All ingots were rolled and swaged, commencing at 850°C, to 1/4-in.-diameter bar. The bars were then annealed at 850°C for 1 hr (except that the 10 and 20 pct V alloys were heated for 2 hr) to give a uniform equiaxed grain size of about 0.05 mm. Tensile samples of 0.125 in. diameter by 0.8 in. gage length were utilized for studies of the ductile to brittle transition. A second set of tensile samples were utilized for microstrain experiments in which strain sensitivity of 1 x 10"6 was achieved by a capacitance method.3 Cylindrical compression samples 0.250 in. diameter by 0.4 in. long also were prepared to study the influence of composition on the macroscopic yield stress, and for metallographic analyses of defor-

Jan 1, 1965

By E. A. von Hahn, T. R. lngraham

The rates of cementation of pd11 on electropolislzed copper cylinders were studied in aqueous perchloric acid solutions at pdII concentrations from 0.02 to 0.1 mM. The cylinders were rotated at various high speeds to reduce the diffusion layer to a minimum thickness. In 0.1 M HClO4 solutions, the cemented palladium is dense, adherent, and shiny. The rate data indicate that there are two stages in the deposition. In the initial stage, the rate of cementation is first order with respect to the pd11 concentration. The second stage is much slower. The first stage is consistent with rate control by the diffusion of pd11 ions to the copper surface, and/or chemical reaction at the surface, and the second stage is consistent with rate control by the diffusion of copper ions from the cop-per surface through the deposit of cemented palladium, out to the main body of solution. In 0.001 M HClO4 solution, only the first stage is evident and the rate is more rapid than at higher acidities. This rate enhancement is attributed to PdOH+ ions that predominate at low acidity and aye more reactive than unhydrolyzed pdII. The deposit is porous and loose. All of the cemented deposits are Pd-Cu alloys rather than pure palladium. Activation energies are 9.5 kcal per mole in 0.1 M HClO4 and 7.4 kcal per mole in 0.001 M HClO4. CEMENTATION or displacement reactions occur between aqueous solutions of metal salts and immersed metals according to the general equation: where M1 is electrochemically the more noble metal. Although these reactions find considerable application in metals recovery processes (e.g., the cementation of copper192 or gold3), in electrorefining processes (e.g., solution purification before electrolysis4,5), and in plating and metal finishing processes,6 few studies have been made of the kinetics of such reactions.7-9 The rates of cementation reactions will depend on one or more of the following factors: a) chemical reactions at the metal-solution interface; b) ionic transport to or away from the interface;'-' and c) the character and adherence of the cemented deposit on the substrate metal,6a,10 because the deposit will inhibit the rate of transport of dissolving ions (M2m+) into the solution. In this investigation, the kinetics of the early stages of cementation were studied to obtain an understanding of the reaction mechanism under conditions in which the deposit was sufficiently thin that its inhibiting effect could be disregarded. To achieve this, very dilute solutions in Mn+ were used. Cementation rates are often fast in the initial stages and transport-contr01led.9 To find conditions under which transport control would shift to chemical control, very high stirring velocities were used to minimize the diffusion-layer thickness. Of the many possible cementation reaction systems, the palladous perchlorate-copper system was chosen for this investigation because it was believed to involve simple ion-for-ion exchange. In addition, there are no interfering side reactions, such as the reduction of hydrogen ions, and anion effects are usually absent in perchlorate solutions. EXPERIMENTAL Materials. Reagent-grade chemicals and redistilled water were used in all experiments. Palladous perchlorate stock solutions (0.02 M) were prepared by dissolving 99.5 pct Pd sponge (Johnson Matthey and Mallory Ltd.) in concentrated nitric acid, adding concentrated perchloric acid, evaporating twice slowly (to prevent PdO precipitation) to a small volume, and diluting in a volumetric flask. To prevent gradual hydrolysis of PdII, the stock solutions were made 0.4 M in HC104. Tests for pdIV (Ref. 11) and C1- were negative. Copper strips were cut accurately from 0.025-in. electrolytic tough pitch sheet, Sample 1 (Mines Branch stock or Canadian Copper Refineries Ltd., Montreal), or from oxygen-free, high-conductivity sheet, Sample 2 (American Metal Climax O.F.H.C. brand, sold by Utility Brass and Copper Corp., Brooklyn). The strips were annealed for 1 hr at 335°C in a stream of purified nitrogen (Union Carbide, Linde Division) which had

Jan 1, 1967

By G. R. Belton, Y. K. Rao

A galvanic cell, using liquid MgCl2 or MgC12-CaC12 mixtures as the electrolyte, has been used to determine activities in Mg-A1 liquid alloys between 700' and 880°C. The incovporation of a chlorine electrode in the cell also allowed measurements to be made of the standard free energy of formation of MgCl2(l). The results are shown to be in good agreement with thermo-chetrlical values from the literature, and this is taken as evidence that the small, known solubility of magnesium in iMgCl2 introduces no significant error in galcanic cell measurements. Within experimental error, the activity coefficients and relative partial molar enthalpies at 800°C are shown to be represented by the following "subregular" solution equations: logy~~ =-0.68(1 -xMgj3 log yAL =-1.02(1 - XMf + 0.68(1 - XMf H.M = -4400(1 - %)3 / cal Mg 7Ag' HZ =-6600(1 - xA1)' + 4400(1 - XMf cal SCHNEIDER and toll' have used a transpiration technique to measure the vapor pressures of magnesium over Mg-A1 alloys between 544" and 594°C. amsstad,' however, has since suggested that the extrapolation to zero flow rate, used by these authors in interpreting their apparent pressure vs flow rate data, gives unreliable results. Rogers, Tomlinson, and Richardson,3 in interpreting the results of solution equilibria between Mg-A1 alloys and liquid MgC12, also considered the measurements of Schneider and Stoll to be unreliable and preferred to derive activities for the alloys from the earlier boiling point determinations of ~eit~ebel~ and the partial molar heats recommended by Kubaschewski and ~atterall.~ These latter heats were based substantially on the early calorimetric work of Kawa-kami but, unfortunately, his work on other systems has sometimes been found to be inaccurate.7 Rogers et al., in the above-mentioned paper,3 tentatively concluded that the most likely species responsible for the limited solubility (0.3 mole pct at 800°C) of magnesium in MgC12 were Mg° (neutral) and Mg2++. Two more recent studies8,9 have supported Mg2++ as the soluble species. In the present study, activities in Mg-A1 alloys have been determined by means of a galvanic cell involving liquid MgCl2 or MgC12CaCl, mixtures as the electrolyte. Since the reactive nature of magnesium precluded simple Faraday yield experiments, a chlorine electrode was incorporated in the cell in order that the performance of the cell could be checked by measurements of the heat and free energy of formation of MgC12. This procedure was considered necessary since it has been suggested1' that the solubility of a metal in a molten salt might introduce electronic conductivity; also, previous determinations of the standard electrode potential for MgC12 differed by as much as 70 mv11-13 EXPERIMENTAL Materials. Analyses of the materials used in preparing the alloys and the electrolyte mixtures are presented in Table I. The alloys were prepared by induction melting weighed amounts of the metals in a graphite crucible held under an argon atmosphere. Pure anhydrous magnesium chloride was prepared by heating the mixture MgCl, . 6H20 +NH4C1(1:1) to 650°C, followed by melting under dry argon. The melting point of the dry MgC12 was found by differential thermal analysis to be 714.8oC, which compares well with the accepted value of 714C.14 This agreement was taken to be an indication of the high purity of the dried salt. Table I. Compositions of Materials, wt pn Impurity Mg Al MgCI2 CaCI, Ba - - 0.005 Ca - - 0.010 Cu 0.02 0.02 Fe - 0.10 0.001 0.010 Pb 0.01 - 0.001 0.005 Mn 0.15 0.001 Si - 0.10 Sr - - 0.005 MBSO* - 0.040 ARGON TUNGSTEN CHLORINE LEAD—411 11 II ALUMINA 'A I / ave GRAPHITE on irA~_ ( ^"l ROD MAGNESIUM S>ILICA~^ /, OR ALLOY-. I /A] ___________ -«^- _ ELECTROLYTE I y FRITTED DISCS Fig. l—Arrangement of chlorine and metal electrodes in electrolytic cell.

Jan 1, 1970

By Merlon C. Flemings, Theodoulos Z. Kattamis

Examination was made of the distribution of tnanganese and nickel in colutrrnar dendrites of a cast low-alloy steel; more limited work was corzducted on chromium. Corresponding "segregrction ratios" were calculnted and shown to be relntivelv insensitive to cooling rate (''segregation ratio" is defined (Is the ratio of maximum to minimum concentrations within a volume whose dimensions are the order of the dendrite-arm spacing). Isoconcentratiorl curves were determined by the electron micropvobe and by rt7etallografihic studies on specimens subjected to isothermal-transformation treatments. From construction of isoconcentration curves, morphology of columnar dendrites is descvibed as intermediate between Perfect rodlike and sheetlike morphologies. The study is extended to equiaxed dendrites and it is shown that the strcture of these dendrites is sittlilar in many respects to that of columnar dendrites. On the basis of tlze sheetlike morphology of dendrites, a simple model is pvoposed for calculation of honzogenization kinetics. Results of trzatllevlatical analysis brcsed on this utzodel are given. This analysis relates residual segregation to time at homogenization temperature; it is in agreement with experiment. Calculations are given which show that even for relatively rapidly cooled material (of 1-ine dendrite-artn spacing) treatmets at 1200°C or above are necessary to achieve slgxificant Izomogenization of elenlents other than carbon itz reasonable time (e.g., rnangclnese, nickel). Conlplete homogenization of carbon is obtnined at much lowev tenlperatures (below 870°C). IN dendritic solidification of castings and ingots, solute redistribution during freezing results in mi-crosegregation of most alloy elements. The micro-segregation is such that minimum solute concentrations occur at the center of dendrite arms and maximum concentrations occur between dendrite arms. Residual segregation after subsequent therma1 processing (homogenization) depends on maximum and minimum initial concentration, on the detailed geometry of the isoconcentration surfaces within interdendritic regions, on the diffusion coefficient of the solute, and on time of thermal processing. The objective of this work was to determine, for a low-alloy steel, maximum and minimum concentrations, and the geometry of isoconcentration surfaces, primarily in order to permit calculation of homogenization kinetics. Most of the work reported was conducted on Samples from a unidirectionally solidified, fully columnar ingot. This type of ingot is made by extracting heat during solidification from one face; techniques for accomplishing this have been discussed.' Samples were taken at several locations, up to 5.75 in. from the mold chill face; the bulk of the work was performed on samples at 5.75 in. Alloy cast was, nominally, 0.4 pct C, 1.8 pct Ni, 0.8 pct Cr, 0.7 pct Mn, 0.25 pct Mo, 0.3 pct Si, and the balance iron. Brief study was also made on samples from an ingot which solidified with equiaxed grain structure. SAMPLE PREPARATION AND ANALYSIS Samples for electron-microprobe analysis were incorporated in mounts that included pieces of electrolytic nickel, chromium, and manganese, in order to normalize the intensities of these solutes in the specimens; also, a piece of electrolytic iron was included to measure the background. All specimens were polished in the usual metallographic manner. After the microprobe traces were made, the path was revealed by etching the specimens with picral. All microprobe analyses were made by point counting, integrating for 30 sec. The distance between points was fixed from 2 to 10 p, according to the precision desired in each case, the fineness of the structure, and the concentration gradient existing in a given area. (The distance was chosen 2 to 5 p near the maximum-concentration regions and 5 to 10 p near the minimum concentration.) The "take-off" angle for the A.R.L.-Model No. 21000 microprobe employed was 52.5 deg. Samples for metallographic analysis of isoconcentration curves were prepared by austenitizing at 1540°F for 20 min, quenching to the nose of the TTT curves (1200°F), heat treating isothermally at this temperature for a given time 0, and then quenching to room temperature. Due to concentration gradients existing in a dendritic structure, no transformation will take place for a given time 0 of isothermal heat treatment in the regions where the a.lloy concentration is higher than a given limit. Thus, the dendrite appears limited by an isoconcentration curve and can be made to appear to grow by varying the time of isothermal heat treatment.

Jan 1, 1965

By R. W. Hertzberg, F. D. Lemkey, J. A. Ford

The effect oj unidirectional solidification upon the microstructural, crystallographic and mechanical characteristics of high -purity A1-A13Ni eutectic a1loy specimens has been investigated. varying the growth rate caused the morphology of the Al3Ni phase to gradually change from platelets to rods. In addition, the effect of increasing the rate of planar liquid-solid interlace movement is to decrease the Al3Ni rod diameter and inter-rod spacing. The platelets and rods grow approxinlately parallel to each other and are aligned in a faulted substructure. A single unique crystallographic relationship hetween the A1 and ASNi phases was found and may he descrihed as : interface {001} Al3Ni {331} Al and growth direction <010>Al3Ni || <110> Al The platelet interlace and the aligned rows of rods are both uniquely defined by the above statements. Alignment of the Al3Ni phase by unidirectional solidification has given rise to a threefold increase in strength over that exhibited by specimens with an as-cast microstructure. These results illustrate the possible use of this eutectic alloy as a zohisker -reinforced structure. It has been demonstrated by Winegard et al.,1 Kraft and Albrighht,2 Chilton and winegard,3 Chad-wick,4 Yue,5 Tiller,6 and others that a planar liquid-solid interface may be established in binary eutectic alloys by proper control of heat flow during the solidification process. The unidirectional movement of such an interface results in a eutectic mi-crostructure consisting of an essentially parallel array of the two phases over an entire ingot. Two dominant phase micromorphologies have been produced using this technique: that of substantially parallel alternating lamellae of each phase or long thin parallel rods of one phase imbedded in a continuous matrix of the other phase. While not all eutectics can be controlled in this manner, it has been shown that a "normal" eutectic may, under properly controlled conditions of purity, liquid and solid thermal gradients, and solidification rate, be forced to solidify with essentially parallel phase particles. Kraft and Albright2 have demonstrated that, when the growth rate is too rapid or when the thermal gradient in the liquid at the growing interface is too low, a layer of constitutionally supercooled liquid, formed by impurity build-up, will stabilize a cellular rather than a planar interface. The unidirectional movement of the cellular interface forms the macrostructure of eutectic colonies.7 Chilton,3 Chadwick,4 and Tiller,&apos; studying eutectics of zone-refined Pb-Sn, A1-CuAl2, Zn-Sn, and Cd-Zn systems, noted that in the absence of impurities a planar interface is stabilized even when rapidly solidified. Although it is generally agreed that impurities break down a planar interface to form the eutectic-colony macrostructure, at present the origin of the varying micromorphologies (i.c., plates or rods) in a given normal eutectic alloy is not completely understood. Tiller8 has predicted that the micromor-phology produced may be dependent on solidification rate (i.e., at fast rates a rodlike structure is preferred whereas at slow rates a lamellar structure should form), and also suggested that rod formation may be favored at large phase-volume ratios. yue5 has experimentally verified Tiller&apos;s prediction in the eutectic Mg-Mg17Al12 by observing a lamellae-to-rod transition with increasing growth rate where the phase-volume ratio was approximately 2.3:1. However, Hunt and chilton9 more recently unidirec-tionally solidified over a wide range of growth velocities six different eutectic systems with phase-volume ratios between 12:l and 2.7:1 and observed no lamellae-to-rod transition. chadwickl0 has proposed that the change in micromorphology in some eutectic alloys is due entirely to the presence of impurities and further states that the lamellar structure is the characteristic structure of pure eutectic alloys even when the phase-volume ratio is as great as 12:l. Kraft11,12 has shown that the parallel lamellae in certain eutectic alloys assume a unique crystallographic relationship during unidirectional growth. This preferred crystallography may be developed

Jan 1, 1965

By Michael Hoch, Walter C. Wyder

The isothermul section of the Nb-Ti-Zr-O system at 1500°C was investigated using X-ray dzffraction and metallographic techniques. UP to 66.7 at. pct 0, the system contains nine four-phase regions. Tsopleths at 10, 20, 30, 40, 50, and 55 at. pct 0 weye constructed. The purpose of this investigation was to determine the general shape of the quaternary equilibrium phase diagram of niobium, titanium, zirconium, and oxygen at 1500°C. The system was truncated at 66.7 at. pct. O., PREVIOUS INVESTIGATIONS The Ti-Zr-O system was investigated in this laboratory.&apos; The binary systems of interest have been compiled and discussed by anssen2 and Levin, McMurdie, and Ha11. Elliott4 has determined the Nb-O system by metallographic and X-ray diffraction techniques. He shows the existence of three oxides, namely NbO, NbO2, and Nb2O5. At 1500°C the solubility of oxygen in niobium is about 4 at. pct. No solid solubility region is shown for either NbO or NbO2. EQUIPMENT The same equipment as that for the study of the Ti-Zr-O system was used. The X-ray diffraction patterns were analyzed with the help of the ASTM card set5 and NBS circulars.6 MATERIALS The niobium powder (99 pct pure), the titanium powder (99.6 pct pure), the niobium pentoxide, and the zirconium dioxide used in this study were purchased from the Fairmount Chemical Co., Newark, N.J. The zirconium powder (99.4 pct pure) was obtained from the Charles Hardy Co., Inc., N.Y. Reagent-grade titanium dioxide was purchased from the Matheson Co., Inc., Norwood, Ohio. The oxides were dried in air at 700°C for 24 hr before use. Though the materials used were not "hyper-pure," the impurities present do not affect the results (lattice parameters, phase boundaries), within the experimental accuracy. PROCEDURE Samples of the desired compositions were made up, in mole pct, from the materials listed above. In some cases the intermediate binary compounds, such as NbO and TiZrO4 were prepared beforehand and used in the preparation of the samples. This technique enabled equilibrium to be reached from two sides. The components of each sample were mechanically mixed in a mortar and pestle and pressed into 3/16-in. diam pellets. The pressures used in compacting were of the order of 50 to 100 x 103 psi. Sintering was accomplished by heating the samples in a tungsten crucible (3/4-in. high, %-in. diam, 1/8-in. wall, lid with XB-in. hole). The pellets were separated from each other and from the crucible by means of small spiral coils of tungsten wire placed between the stacked pellets and on the bottom of the crucible. The sintering time was from 4 to 12 hr at 1500°C under a vacuum of 6 x 101-5 to 1 x 10-6 mm of Hg. All samples were reground after the first or second heating repressed, and reheated. In most cases: equilibrium was obtained after the first heating, as the X-ray diffraction pictures after each heating remained unchanged. Quenching of the samples from 1500°C was at first only possible by allowing the crucible and its contents to lose heat by radiation. The temperature dropped from 1500° to 900°c in approximately 1 1/2 min, which was considered adequate when compared to the times used by other investigators to reach equilibrium in the temperature range of 1000°c and lower. Later, a new technique for faster quenching of the samples was cleveloped. This technique involved the removal of the samples from the crucible, whereupon they were quenched by coming in contact with the water-cooled copper base of the furnace. This manipulation was performed without breaking the vacuum. The sample pellets were placed on a tungsten wire rack inside the crucible. The wire rack passed through the hole in the crucible lid, where it was connected to a small nonmagnetic chain. The chain was fed to the side of the furnace by means of a brass rack which fitted between the body and lid of the furnace. Suspended at the end of the chain, near the furnace wall, were three magnetic washers. With the use of a strong

Jan 1, 1962

By C. P. Lawhon, J. P. Simpson, W. M. Evans

Recent efforts to design drilling fluids for increased drifting rates have confirmed some laboratory results of other investigators, but have also produced additional data that should be considered. These data were obtained under controlled test conditions using a microbit drilling machine. Clays and some polymers have previously been reported to cause reduction in drilling rate. Recent data have shown that under laboratory conditions, suspensions of a single day or polymer have sometimes given faster drilling rates than when water was used. Measurements have been made of clay suspensions and polymer suspensions comparing filtration (I) under API conditions, (2) while drilling with temperature of 150F and differential pressure of 1,000 psi and (3) under dynamic conditions after drilling. Some correlation between instanraneous filtration (white drilling) and drilling rate has been observed. INTRODUCTION Several papers have been presented that related drilling fluids to penetration rate. Generally, it was found that a decrease in the solids concentration resulted in significant increases in the drilling rate. Of course, this change also resulted in a decrease in the viscosity of the drilling fluid.&apos; Conclusions from investigations by this laboratory are in agreement. Data have shown that of the simple mud measurements commonly made at the drilling rig (density, plastic viscosity. yield point, API filtrate and total solids), only the density and total solids have a significant relationship to the drilling rate in Berea sandstone when attempting to correlate a single mud property individually.&apos; More recent drilling rate experiments have been designed to study (1) effects of individual clays and polymers on drilling rates in Berea sandstone and Lueders limestone, (2) the relationship between drilling rate and dynamic filtration as measured after drilling and (3) the relationship between drilling rate and dynamic filtration as measured during drilling. Data show that drilling rates are dependent upon type and concentration of particles, type of formation and filtration of the individual fluids while drilling. Mud pressure: pressure of drilling fluid as measured after leaving the drilling chamber (Fig. 1). This is taken to be approximately the mud pressure just past the bit and at the face of the formation. Terrastatic pressure: pressure representing weight of overburden. Formation pressure: pressure of formation fluid as measured at outlet of drilling chamber (Fig. 1). This is taken to be approximately the pressure of fluid in the interstices of the formation. Differential pressure: difference between the mud pressure and formation pressure. LABORATORY EQUIPMENT AND TESTING PROCEDURE The drilling equipment was described in two previous publications."&apos; Main components are a drilling chamber, filter-heater, rotary drive and variable-speed circulating pump. Auxiliary pumps supply pressure boosts for the mud, terrastatic and formation pressures. All equipment is designed for 15,000 psi and 500F. Capacity of the circulating system is approximately 7 gal. The mechanical design was facilitated by moving the rock down onto the bit. Data collected with this design should not differ from that obtained by a normal design where the bit moves into the rock. Drilling fluid is pumped through 50 ft of ID pipe coiled in an oil bath, enters the rotary shaft at a right angle and is pumped through the jets on the bit (Fig. 1). Most of the drilled solids are extracted by a screen mounted in the circulating system on the suction side of the pump. Data reported in this paper were obtained by controlling these parameters: mud pressure, 5,000 psi; formation pressure, 4,000 psi; terrastatic pressure, 5,000 psi; force on bit, 1,000 Ib; formation, Berea sandstone and Lueders limestone; flow rate, 7 gal/rnin; bit, 11/4-in. diameter with two 0.078-in jets; mud temperature. 150F; and rotary speed, 60 rpm. Mud pressure was controlled at 5,000 psi, thus giving a differential pressure of 1,000 psi even though the fluid densities varied. Cores of 3%;-in. diameter and 8 in. long were selected from quarry blocks to provide some control of grain size distribution, permeability and porosity. A 2-in. section was cut off each core and a I -in. diameter plug was taken from this section. Permeability to 5 percent by weight sodium chloride solution was determined and the large cores were

By K. M. Rolls, J. Wulff, D. A. Colling

Solid-solution alloys of the Ta- Ti system containing up to 70 at. pct Ti were melted and fabricated into wire. Steady magnetic-field measurements of cold-worked wires at 4.2°K indicate that the resistive critical field increases smoothly with increasing titanium, reaching a maximum of 93 kG (J = 1 amp per sq cm) for a composition of about 50 at. pct Ti. The composition dependence of the resistive critical field indicates it is largely paramagnetically limited for alloys containing more than 35 at. pct Ti. For cold-worked wires the value of the critical current density, Jc , was found to be insensitive to composition changes for compositions in excess of 20 at. pct Ti. It was observed that Jc could be increased by final-size heat treatment at 400°C without altering the value of- the resistive critical field. Experimental data are used to calculate the electronic specific-heat coefficient and the "upper critical field" for the alloys studied. THE effect and importance of metallurgical structure on superconducting properties have been summarized by Livingston and Schadler.1 Specific work on solid-solution alloys such as Nb-zr2-7 and Nb-Ti5-7 have shown that critical current density (Jc) and superconducting transition temperature are structure-sensitive. Berlincourt et al.6,8,9 in their studies of transition-metal alloys find that Ta-Ti alloys remain superconducting at fields comparable to Nb-Ti alloys. 6,8 Transverse critical current tests of a Ta-10 at. pct Ti alloy10 and longitudinal critical current tests of a Ta-25 at. pct Ti alloy1&apos; indicate that such alloys are capable of carrying high currents at intermediate fields (-40 kG). The work reported in the present paper was undertaken to explore the superconducting properties of further compositions in the Ta-Ti alloy system as well as the structure sensitivity of the superconducting properties. I) EXPERIMENTAL PROCEDURE Alloys were prepared by melting tantalum (Fansteel Metallurgical Corp., 99.96 pct purity) and iodide, crystal bar titanium (Foote Mineral Co., 99.92 pct purity) mixtures in an arc furnace on a water-cooled copper hearth using a tungsten electrode. Melting was accomplished in a purified, gettered argon atmosphere at pressures from 250 to 400 Torr. Each alloy was turned and remelted fourteen times to assure complete mixing of tantalum and titanium. Ex- cessive coring in the cast samples was, nevertheless, observed. This was somewhat reduced by annealing in vacuo at 1000°C for 13 hr. The ingots were then machined to 0.250 in. diam, jacketed in Type 304 stainless-steel tubing, and swaged to 0.140 in. diam. They were then drawn to 0.010-in.-diam wire. Alloys containing up to 70 at. pct Ti were readily cold-drawn to wire in this manner. Later experiments showed that oxygen additions up to -3000 ppm could also be cold-worked into wire. Test samples for superconductivity measurements in the 2-in, air-core Bitter solenoids of the M.I.T. National Magnet Laboratory were prepared from 10-in. lengths of 0.010-in.-diam wire, cleaned of residual wire-drawing lubricant. Current contacts were made by clamping clean copper tubing over both No. 18 current lead wire and the ultrasonically indium-tinned ends of the specimen wire.12 Potential leads of No. 32 copper wire were connected to the specimen by ultrasonic soldering in an indium bath. The potential lead separation was about 4 cm, corresponding to the circumference of the Bakelite rod to which the wire was affixed with half-mil Teflon tape. The final specimen configuration is shown in Fig. 1. Specimens were lowered into a liquid helium bath (4.2oK) in a double solenoid dewar and positioned so that the maximum magnetic field was oriented transverse to the wire axis of the gage section. Measurements were made by passing a current through the specimen at a preset solenoidal magnetic field. The current was increased until a 1-pv potential difference appeared across the gage section (1/4 µv per cm). At low magnetic fields, however, it was not possible to use this criterion because power-dissipation difficul-

Jan 1, 1967

By W. A. Backofen, D. H. Avery, G. A. Miller

An evaluation has been made of the relative importance of yield strength (?) and stacking-fault energy (y) to the rate of fatigue-crack growth in materials of fcc structure. Pure copper and its solid-solution al-loys with aluminum and nickel were chosen for the study because they provided sufficient range in both quantities of interest that either could be varied independently of the other. Experiments involved alternating tension and compression of flat specimens which were prepared with sharpened internal notches so that most, if not all, of the crack-nucleation interval could be eliminated. Growth rate (dC/dN) was concluded to be proportional to the square of the plastic-strain amplitude (€,,) over a strain range of approximately 6x 10-4 to 6 x 10-3. The factor, k, linking dC/dN and ep in dC/dN = kEp2 increased and decreased with corresponding variations in y, but it did not respond syste?>/atically to change in ay, indicating that y is the significant variable in crack growth at constant plastic-strain amplitude. In polycrystalline material, k varied by a factor of 5 over the available range of y. In a few single-crystal experiments on Cu-A1 alloys the growth rate responded less strongly to change in y. It has been suggested that single crystals behave somewhat differently than poly crystalline material because there is more extetnsive substructure near the grain boundaries in the latter, and this facilitates crack advance by separation along subgrain boundaries. A point of some controversy in current work on fatigue relates to the effects of strength and stacking-fault energy on crack growth. In recent experiments a separation was made between the cycling intervals for crack nucleation and the subsequent growth that eventually ends a specimen&apos;s fatigue life.&apos; The study was carried out on Cu-A1 alloys primarily, fatigued in alternating four-point bending to constant deflection. A nucleation interval of about 10&apos; cycles (at a total strain amplitude = 0.2 pct) was found to be insensitive to aluminum content in the range 0 to 7.5 wt pct, while the growth period was increased approximately forty fold over the same compositional range. The increase was not in any sense linear, however. Rather, most of the change occurred below 4 pct A1 or a stacking-fault energy, ?, of about 15 ergs per sq cm. It was argued that the plastic-strain amplitude was approximately constant, and therefore the effect of composition must have grown out of the reduction in stacking-fault energy. Several studies have shown that, with high ?, cross slip is encouraged, subgrain structure is introduced during fatigue, and cracking is aided through propagation along subgrain boundaries.1-5 Therefore, lowering ? sufficiently to interfere with substructure formation would be expected to retard growth rate. On the other hand, it is a general rule that resistance to fatigue cracking increases as strength is raised. Accordingly, there might still have been some doubt that Y was the controlling variable, since strength would be increased as y was lowered by the aluminum additions. To help in dispelling that doubt, an experiment was made on a polycrystalline Cu-Ni alloy similar in strength to the Cu-A1 alloys but of higher ?; the crack-growth interval was found to be essentially that of pure copper.&apos; Further support for this position on stacking-fault energy as it relates to crack growth is derived from work by Boettner and McEvily,6 in which the actual crack-growth rate was measured on samples previously notched so as to minimize the nucleation period. Unfortunately, it was necessary in isolating strength level to compare different alloy systems and grain sizes. Recognizing the complication, it was still concluded that growth may be retarded by a reduction in y, per se. A related study has also been made by Roberson and Grosskreutz.7 The zinc content of a brass was systematically changed to alter strength and stack-ing-fault energy, although not below the 15 ergs per sq cm at which pronounced change in growth interval was found in the earlier work. The results were limited to more or less conventional S-N diagrams so that nucleation and growth events could not be separated. No definite conclusions were drawn, but

Jan 1, 1967

By M. F. Burr, F. V. Lenel, G. S. Ansell

The mechanism of materials transport was studied in a model experiment in which a silver sphere was sintered to a silver plate under an applied external stress near 800° C. For this purpose the rate of growth of the neck between the sphere and the plate which is proportional to the strain rate of the creep process involved in a neck growth was determined by measuring the change in electrical resistance of the away. This rate of neck growth will depend upon the magnitude of the applied external stress. By measuring the rate just before and just after a change in the external load and therefore the applied stress, the relationship between strain rate and stress can be derived. For material transport by slip in a pure metal it is expected that the strain rate should be proportional to the 4.5th power of the stress, while for transport by diffusional flow the strain rate should be proportional to the first power of the stress. It was found that for stresses above 5 X 10&apos; dynes per sq cm (70 psi) the exponent in the stvain rate-stress relationship was near 4.5 while for a stress of 0.7 x 108 dynes per sq cm (10 psi) an exponent of 1.8 was determined indicating that under the conditions of the experiment the transport mechanism for creep in silver shifts from diffusional flow to slip in the region of 0.7 x 106 dynes per sq cm (10 psi). The importance of these findings for an understanding of the mechanism of material transport in conventional sintering (without an external load) is pointed out. In a paper by Early et al.,&apos; the mechanism of material transport during sintering was treated as a creep process. It was pointed out that two possible types of creep processes could operate during sintering. In one of these material transport takes place by vacancy diffusion due to a gradient in chemical potential. The vacancy sinks in this diffusion process may be either grain boundaries, as in Herring-Nabarro microcreep, or regions beneath a surface of small radius of curvature. The diffusive transport may be by volume, grain boundary, or surface diffusion. In the other mechanism, creep takes place by slip, i.e., dislocation motion with its rate generally controlled by dislocation climb. One method of distinguishing between these two modes of materials transport is to investigate the creep rate, i.e., the rate of material transport as a function of stress. For material transport by vacancy diffusion, the creep rate is proportional to the stress.&apos; For creep by slip, controlled by dislocation climb, the creep rate is proportional to a power of the stress. For pure metals this power is 4.5;374 for dispersion-strengthened material a fourth power relationship can be derived.5 This difference in the stress dependence of the strain rate is illustrated schematically in Fig. 1, in which the logarithm of strain rate is plotted vs the logarithm of the stress for material transport in a pure metal by vacancy flux and by dislocation climb. The stress range in which the two types of material transport overlap would be expected to be relatively small. In the experiments described by Early and coworkers compacts pressed from spherical copper powder were sintered isothermally under an applied axial external load in a dilatometer. During sintering the magnitude of the applied external load was changed and the rate of axial shrinkage of the compact before and after the load change determined. In order to find the stress dependence of the strain rate the magnitude of the stress acting on the neck area between the spherical particles before and after the load change had to be calculated. This stress is the resultant of the stresses due both to the externally applied load and to surface tension. The stress due to surface tension is a function of the geometry of the powder compacts. It can be determined, at least for simple geometrical arrays,&apos;76 but it is difficult to obtain exact values of the stresses for actual powder compacts when only average values of particle diameters and of neck diameters between particles are available. The calculation of stress and the strain rate-stress relationship is therefore only very approximate.

Jan 1, 1968

By N. J. Grant, R. Nordheim

An extensive study was made of the aging characteristics of alloys based on the 80 pct Ni-20 pct Cr composition hardened with aluminum and/or titanium, each up to 4 pct. Aging was followed by means of hardness and hot electrical resistance measurements as well as by X-ray and microscopy. Stress rupture tests at 1500°F were utilized as a check on the predicted behavior. THE titanium and aluminum hardened Ni-Cr alloys, exemplified by Nimonic 80 and Inconel X, constitute one of the more important groups of alloys developed to meet the demand for materials retaining their strength at elevated temperatures. For service in the temperature range 1200" to 1500°F, these alloys offer high creep resistance. With increasing service temperature, however, the strength of the simpler Ni-Cr base alloys falls off rapidly so that above 1500°F there is a significant loss of strength. The present investigation was undertaken with the hope that a better understanding of the factors controlling the precipitation hardening of these alloys would make it possible to increase the useful service temperature range. Primarily this investigation involved the study of the effects of titanium and aluminum on the hardening and the subsequent softening at elevated temperatures. The titanium and aluminum contents were each varied between 0 and 4 pct by weight at a constant nickel to chromium weight ratio of about 4:1. (Except when otherwise stated, all compositions are expressed on a weight basis.) The major part of the investigation was confined to alloys with less than 0.06 pct C. Recently several papers dealing with the identity of the microconstituents in the titanium and aluminum hardened Ni-Cr alloys have been published. Using X-ray analysis of the residues from anodic dissolution, Rosenbauml was only able to identify carbides and nitrides in Nimonic 80 and Inconel X. However, since Rosenbaum worked with alloys in the hot rolled rather than in the aged condition, his results are inconclusive. Recently Hignett&apos; reported that the hardening of Nimonic 80 was due to the controlled precipitation of Ni,(TiAl) having the cubic Ni3A1 structure. Taylor and Floydv-" published the results of an investigation of the nickel-rich corner of the Ni-Cr-Ti, Ni-Cr-Al, and Ni-Ti-A1 systems. In the Ni-Ti and the Ni-A1 systems the hexagonal Ni,Ti phase, 7, and the cubic Ni3A1 phase, -y&apos;, respectively, exist in equilibrium with the nickel-rich solid solution. The interatomic distances in the basal plane of Ni,Ti and the octahedral planes of the matrix are almost equal, thus explaining the Wid-manstaetten type structure formed when Ni,Ti precipitates from solid solution. When Ni:,Al precipitates from solid solution, it appears usually in globular form, often dispersed along rows corresponding to definite crystallographic directions. The 7 and phases are also the only intermetallic compounds which occur in the nickel ternary alloys with up to 25 pct Cr and 10 pct Ti or Al. Taylor and Floyd found that Ni,Ti takes practically no nickel, chromium, or aluminum into solution. Nial, on the other hand, dissolves a considerable amount of chromium and titanium and some nickel. Up to three out of every five aluminum atoms could be replaced by titanium in Ni,Al. This substitution caused a slight increase (less than 1 pct) in the lattice parameter. With respect to the effect of variation in the titanium and aluminum contents on the high temperature strength of Nimonic 80 type alloys, Pfeil, Allen, and Conway" reported that an 80 pct Ni-20 pct Cr alloy containing 0.20 to 0.30 pct A1 had the highest creep resistance when the titanium content was kept between 1.65 and 2.75 pct. Experimental Procedure The materials used for this investigation were electrolytic nickel, electrolytic or low carbon chromium, sponge titanium and 2s aluminum. The alloys were melted in an indirect carbon arc furnace under

Jan 1, 1955

By V. F. Hollister

The Queen Charlotte gold deposit (also known as the Specogna, Babe, or Cinola) was discovered in late 1970 by Efrem Specogna and Johnny Trico. They were prospecting along the trace of the Sandspit fault, and they sampled jarositic material that included veins from the fault zone. Their assays included some good gold values. They located the Babe Claims in 1971 and optioned them to Kennco Explorations Ltd. Kennco conducted stream sediment and soil geochem studies, geological mapping and drilling of 55.2 m (181 ft) in two drill holes. Kennco withdrew from the property, and by 1977, Cominco, Placer Development, Silver Standard, and Quintana Minerals had each successively worked on the deposit. Consolidated Cinola Mines bought the claims in 1977 and completed exploration of the deposit ultimately in a joint venture arrangement with Energy Reserves. Energy Reserves entered in late 1979, and by 1983, a total of 200 surface and 12 underground drill holes had been completed, totaling 28 600 m (93,832 ft). In addition, a 461.9 m (1515 ft) adit was driven in the ore body. Reserves published by Cinola aggregate 34 Mt (37 million st) of 1.7 g (0.060 oz) Au per tonne. All industry geologists working in the area agree that the Queen Charlotte gold is an epithermal gold deposit in porous volcaniclastic and clastic rocks that is genetically related to a Miocene-Pliocene rhyolite plug. The geologic description here follows the oral presentation made by G. G. Richards, J. S. Christie, and M. R. Wolfhard at a 1976 CIM meeting. Additional comments by the late C. S. Ney of Kennco Explorations are included with the Richards, Christie, and Wolfhard data to complete the geologic set- ting. The attached reprint by Champigny and Sinclair (1 980) provides additional data on the deposit. The Queen Charlotte (Babe, Specogna, or Cinola) gold deposit is located on Graham Island in the northern Charlotte Islands, at the fault boundary of the Skidegate plateau and the Charlotte lowlands. The Sandspit fault marks the physiographic boundary, and it is intruded by rhyolite porphyry at the deposit. Because displaced geochem anomalies, drain- age patterns, and topography suggest dextral and east side down movement for the fault, exposed east block rocks are younger than rocks west of the fault. The east block, which included the ore deposit, is a lowland largely masked by unconsolidated Pleistocene and Recent clastic rocks. Rocks west of the rhyolite plug, on the Skidegate plateau, are Cretaceous carbonaceous and calcareous shale unconformably overlain by a thin veneer of rhyolite tuff. The deposit is about 100 m (328 ft) above sea level. GEOLOGIC SETTING At the ore deposit, the Sandspit fault is a complex structure. However, lithologies on either side of the fault-controlled rhyolite porphyry plug are distinct. West of the rhyolite, the upper member of the Cretaceous Haida formation shale is the most common rock type. The member is composed of dark grey to black, poorly consolidated, and thinly bedded carbonaceous and calcareous shale. The sequence is silicified to an argillite or a hornfels near the rhyolite. West of the rhyolite porphyry plug, but not importantly involved in the mineralization, is a thin masking cover of rhyolite tuff. The tuff unconformably succeeds the cretaceous shale, but it is largely eroded in the mine area. East of the fault-controlled rhyolite porphyry plug is a thick section of conglomerate and sandstone of the Miocene- Pliocene Skonun formation. The ore body occurs within the coarse clastics, the rhyolite intrusive as the western boundary. Ore is entirely contained within the clastics. Original permeability of the clastic rocks was a major control for ore deposition and alteration, and for that reason, the Skonun formation is described in greater detail. The Skonun formation clastics unconformably overlie Haida shale. The Skonun is at least 300 m (984 ft) thick in the mine area, where it trends northerly and dips easterly 15º to 25º. The sequence is about 62 percent conglomerate, 3 1 percent coarse arkosic sandstone, and 7 percent interbedded siltstone and sandstone. Contacts between adjacent beds are generally sharp. Stratigraphic correlations between drill

Jan 1, 1985

By H. Carroll Weed

By caving a block into the workings of its open pit and using the block as an ore transfer, the lnspiration Consolidated Copper Co. has solved a transportation and sizing problem, making possible a great expansion of open-pit methods as applied to Inspiration ore-bodies. FROM 1915 to 1948 the entire production of Inspiration Consolidated Copper Co. was supplied from underground mining. The sole method used was block caving. Underground haulage and hoisting facilities were designed and geared to large-scale production. Beginning in 1948 open-pit mining was substituted for block caving in a portion of Inspiration&apos;s Live Oak orebody. The idea proved so attractive that before the Live Oak pit had come into production, another pit on the Colorado orebody (now the Thornton pit) had been laid out and stripping started. It should be noted that these orebodies were not new and the entire program was one of changed methods of mining. Since part of these orebodies had already been mined by block caving methods, it must be recognized that haulage levels had been established under the area or adjacent to it. The orebodies lay on the south side of Inspiration Ridge, while the shafts, crushers, and treatment plants are all on the north side of this ridge. The existing main crushing plant was designed to take a maximum of 12-in. material, and all ore was sized to this dimension by passing through grizzlies in the stopes. In the original planning for open-pit work much thought was given to the transfer of ore to existing underground levels for haulage and hoisting from the regular shafts. If this could be done the necessity of crossing the ridge could be eliminated. Final decision called for cutting a road through the ridge, installation of a primary crusher at an elevation of 3968 ft on the north side of the ridge, and railroad haulage with existing facilities to the main coarse crusher. This decision was brought about by the difficulties of properly sizing and transferring to underground haulage large tonnages of coarse breaking oxide which lay on the upper benches of the proposed pit. Trucking over the ridge on a 7 pct grade would give a cheaper and more flexible operation in handling this material. The benches in the pits are laid out at 50-ft inter-vals and designated according to elevation above sea level. The lowest bench in the original pit was laid out at 3500-ft elvation. All haulage roads are on a 7 pct grade and a vertical lift of 468 ft was considered about the maximum economically possible from a cost standpoint. After 2 years&apos; operation the advantages of pit mining, both from the standpoint of costs and flexibility of operation, became more and more apparent. Studies were then started to develop the extension of open-pit mining to more of the ore reserve than had been planned originally. The idea of transfer raises was again explored. Obviously, as elevation of the pit was lowered, shorter transfer raises would be needed to reach the main haulage levels. Transportation from the lower elevations to the rim of the pit by belt conveyor or skip hoisting was also considered. However, it was recognized that sizing would be required both for conveying and regulation of feed size to the main crusher plant. This would necessitate a fixed or portable crusher located somewhere in the pit. It was known that the sulphide ore at the lower elevations was softer and easier to break than the overlying oxide of the upper benches. This sulphide ore is very suitable for grizzly sizing. Calculations indicated that for ore mined on 3650 elevation, costs for trucking to the primary crusher, crushing, and delivery by railroad to the coarse crusher would equal costs for dropping the same material to the 600 level, hauling underground, and hoisting directly to the coarse crusher bins, provided a suitable method of sizing and transferring could be developed. Above 3650 elevation costs would favor surface haulage; below they would favor underground haulage. The idea of caving an underground block from the 600 haulage level directly into the bottom of the pit

Jan 1, 1954