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By J. Rogers. K. L. Sutherland, E. E. Wark, I. W. Wark

Soaps have hem used as collectors for many years, but only in the last eight years have other long-chain paraffin salts been used. It may be anticipated that these newer collectors will be used mainly with nonsulphide minerals, for which the xan-thates and similar compounds are of little value. On the other hand, the xanthates are both cheap and effective for sulphide ores and seem likely to retain their present cminence in this field. During 1938 and 1939 two of us (E. E. W. and I. W. W.) commenced a comprehensive investigation of the principles underlying the use of paraffin chain salts as flotation reagents. This research was sponsored jointly by the University of Melbourne and a group of Australian mining companies. † A broad, semiquantitative survey was then made of the field covered in the present paper. This was followed in 1940 by further work by one of us (K. L. S.). In 1941 the investigation was taken over by the Division of Industrial Chemistry of the Commonwealth Council for Scientific and Industrial Research, Australia. Discovery of some principles upon which are based the flotation of minerals by paraffin chain salts was followed by their application in the development of processes for the recovery of certain strategic minerals from their ores. Promising results in the flotation of cassiterite from various ores will be described in a subsequent paper. The Paraffin Chain Salts 'he basic requirements for a "collector " in flotation are that it should form a film over the surface of the mineral to be floated, and that this film should be orientated so that hydrocarbon (nonpolar) groups form the effective surface. When modified in this way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince23 that such a film can be produced only if the collector compound contains an active (polar) group to attract it to the mineral surface as well as the nonpolar group. One section of this large class of polar-nonpolar compounds is the paraffin chain salts: CH3(CH2)nX where .X signifies a polar group that ionizes in aqueous solution. Though the compound can ionize, it may be a weak or a strong electrolyte, and the hydrocarbon chain may be in the cation or the anion (Table I). Many compounds of similar constitution are available, but the usual polar groups are: -Co2Na, -So3Na, -So4Na, — PO4Na2, or an aminonitrogen group, the

Jan 1, 1947

By E. E. Wark, I. W. Wark, J. Rogers. K. L. Sutherland

Soaps have hem used as collectors for many years, but only in the last eight years have other long-chain paraffin salts been used. It may be anticipated that these newer collectors will be used mainly with nonsulphide minerals, for which the xan-thates and similar compounds are of little value. On the other hand, the xanthates are both cheap and effective for sulphide ores and seem likely to retain their present cminence in this field. During 1938 and 1939 two of us (E. E. W. and I. W. W.) commenced a comprehensive investigation of the principles underlying the use of paraffin chain salts as flotation reagents. This research was sponsored jointly by the University of Melbourne and a group of Australian mining companies. † A broad, semiquantitative survey was then made of the field covered in the present paper. This was followed in 1940 by further work by one of us (K. L. S.). In 1941 the investigation was taken over by the Division of Industrial Chemistry of the Commonwealth Council for Scientific and Industrial Research, Australia. Discovery of some principles upon which are based the flotation of minerals by paraffin chain salts was followed by their application in the development of processes for the recovery of certain strategic minerals from their ores. Promising results in the flotation of cassiterite from various ores will be described in a subsequent paper. The Paraffin Chain Salts 'he basic requirements for a "collector " in flotation are that it should form a film over the surface of the mineral to be floated, and that this film should be orientated so that hydrocarbon (nonpolar) groups form the effective surface. When modified in this way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince23 that such a film can be produced only if the collector compound contains an active (polar) group to attract it to the mineral surface as well as the nonpolar group. One section of this large class of polar-nonpolar compounds is the paraffin chain salts: CH3(CH2)nX where .X signifies a polar group that ionizes in aqueous solution. Though the compound can ionize, it may be a weak or a strong electrolyte, and the hydrocarbon chain may be in the cation or the anion (Table I). Many compounds of similar constitution are available, but the usual polar groups are: -Co2Na, -So3Na, -So4Na, — PO4Na2, or an aminonitrogen group, the

Jan 1, 1947

By Gerald Edmunds, M. L. Fuller

The development of "fiber" or preferred orientations, during the plastic deformation of metals, and the relation of such structures to the anisotropic characteristics of worked metals has become a subject of common knowledge among metallurgists. Very little has been published, however, relative to variations existent throughout the cross-sections of rolled strips,1 and the influence that such variations may have. This paper presents such a study on a rolled zinc alloy.2 The significance of small differences in surface structure is shown in relation to bending properties. Experience with zinc and its alloys has shown that the outer radius of the bend, which is subject to tensile deformation, is the common region of failure. In considering relations of structural characteristics to bending properties it will suffice, therefore, to consider the ease and possible extent of tensile deformation resulting from various orientations. It is necessary in this connection to assume that on the average the individual crystals of a polycrystalline material act substantially as if their movements were unobstructed by the surrounding grains. This assumption is not strictly valid, but the error involved is unlikely to affect seriously the qualitative conclusions derived from its use. The mechanism of the plastic deformation of zinc crystals has been described by Mark, Polanyi and Schmid3 and by Mathewson and Phillips14 and is regarded as being accomplished by block movements or * Investigator, Rolling Mill Section, Research Division, New Jersey Zinc Co. f Investigator, X-ray Laboratory, Research Division, New .Jersey Zinc Co. 1 Variations of structure throughout the cross-section of wire have been reported in the literature. 2 This alloy contained, in addition to zinc, 1.0 per cent copper and 0.01 per cent magnesium. Its crystal form is hexagonal close packed, the sarne as that of pure zinc. 3 H. Mark, M. Polanyi and E. Schmid: Vorgange bei der Dehrlung von Zink-kristallen. Zlsch. f. Phys. (1922) 12, 58. 4 C, H. Mathewson and A. J. Phillips: Plastic Deformation of Coarse-grained Zinc. Proc. Inst. Met. Div., A. I. M. E. (1927) 143. C. H. Mathewson: Twinning in Metals. Proc. Inst. Met. Div., A. I. M. E. (1928) 7. The results of a further study of plastic deformation of zinc as related to twin-

Jan 1, 1932

By Robert Goodrich

THERE is a small area about Murray where bedded gold quartz veins occur in Prichard slate. The ore taken from the upper levels, during the early days, was free milling and was treated by stamp milling and amalgamation. There was likewise a considerable placer working. The report is current that tungsten (scheelite) was encountered, which interfered with the amalgamation in the stamp mills and which, in placering, collected in the riffles in the sluice boxes and. clogged them. Consequently, in the quartz mines, the scheelite, when encountered, was rejected, being thrown into the waste, sometimes inside the mine and at other times outside on the clump. The free surface ores became worked out and as the ore in depth became pyritic and rebellious to amalgamation the mines closed down. Last spring tungsten ore brought a high price, near $80 per unit, 60 per cent. W03 and up. This so stimulated the output of tungsten ore that old clumps were explored and waste stored in the mines was gone over. Tungsten was likewise mined from virgin ground. So the district produced quite heavily for a time. The condition now is different. The price is not so high, about $20 per unit W03, which makes profits questionable when mining in new ground. The accumulations from early clay mining have been exhausted and the output has greatly declined. The Golden Chest mine was the heaviest producer of tungsten. The months of June and July were spent at this mine studying the problem. Since the mine had produced both gold and tungsten, we looked forward to the problem of recovering both from what might be called a gold-tungsten ore. A study of the Golden Chest vein showed this not to be so there. While gold ore and tungsten ore come from the same vein, the tungsten ore is confined to a more or less disturbed or distorted portion

Jan 8, 1917

By H. Y. Hunsicker

A graphic method has been devised for three-di-mensional analysis of hot deformation and for correlating the amount and directionality of the deformation with resulting directional properties. Deformation is evaluated in terms of dimensional change ratios referred to three orthogonal axes. Since all combinations of the three ratios can be represented in a triangular coordinate field with logarithmic scales, a two-dimensional chart of extent of deformation and degree of asymetry is possible. The entire gamut of shape changes from upsetting through flat-rolling to rod-rolling is accommodated. The resulting coordinate system is a base upon which can be represented the properties of the wrought products measured in the directions of the axes employed fir evaluating the deformation. When property data are available for many types and amounts of deformation, a three-dimensional figure can be constructed, and the projection of this figure is referred to as a ''3d'' chart. Experience in using such charts to plan fabricating operations for a variety of thick-section forged and rolled products of heat-treated aluminum alloys has verified its practical value for optimizing directionality relationships. MechANICAL anisotropy of thick section products of heat-treatable aluminum alloys is recognized by producers and users of these products, and the extent of the directional differences is apparent in property tabulations included in handbooks, standards, and specifications.' Attention has also been directed to the existence of important directional differences in the resistance of these products to stress-corrosion cracking. Metallurgical structure factors responsible for these directional differences include, among other possibilities, shape and alignment of grains, voids and nonmetallic inclusions (when present), volume fraction and spatial distribution of secondary phase particles and solid-state precipitates, crystal-lographic textures, and Bauschinger effect. The contributions of the individual factors vary with alloy composition, heat-treated temper, type of working process (forging, rolling, extrusion), and the amount and directional nature of the deformation. In general, the cast ingot used as the starting material for producing these wrought products exhibits only a modest degree of directionality. A monotonic and continuous transition from this nearly isotropic state with progressive hot deformation would appear probable, assuming that the working temperature is sufficiently high to cause continuous dynamic recovery. Several years ago a project was undertaken to evaluate the effects of hot deformation and metallurgical structures on the directionality of thick wrought aluminum alloy products, and the method to be described was developed as an analytical tool in this investigation. DIRECTION NOMENCLATURE The nomenclature system adopted by industry for the three mutually perpendicular directions employed in testing aluminum alloy products includes four terms: "longitudinal", "transverse", "long transverse", and "short transverse". These terms are conventionally related to the external geometry of the product but also by implication to the deformation and resulting metallurgical structure. Occasions arise in which through use of unusual fabricating methods, intentional or otherwise, the structure does not have the usual relationship to external geometry or may be very complex because of inhomogeneity of deformation throughout the piece. The longitudinal direction is generally parallel to the primary rolling direction or to the direction of extrusion. In the case of forging, it is parallel to the direction of maximum extension (not maximum "working" or "flow", as frequently stated). The term transverse is applied to any direction perpendicular to the longitudinal direction in a product having symmetry about the longitudinal axis, and generally, although not always, the deformation to produce these forms is nearly symmetrical in the transverse plane. This term then may be applied to a round, square, hexagon, or other polygonal, symmetrical shape produced by extrusion or rolling or by forging, if produced by a simple, symmetrical drawing procedure. The type of microstructure generally associated

Jan 1, 1970

By Lawrence K. Jetter, Robert F. Mehl

Some advances have been made recently in the theory of the kinetics of precipitation from metallic solid solution despite the complexities of the problem, but there is surprisingly little quantitative information available on rates of precipitation with which to test present theory or upon which to build new theory. Attempts to measure rates of precipitation have been beset with difficulties which originate both in the anomalies that attend the changes in the properties selectcd for measurement, as, for example, in electrical conductivity or mechanical properties, and also in the complexities in the structural changes in some systems, as in the aluminum-copper system. If the functional relationship between the quantity of precipitate and the value of the selected property is uncertain, measurements of that property are obviously of uncertain utility in determining absolute rates of precipitation. If the precipitating system passes through one or more transition stages, the interpretation of measured rates lacks definiteness; in such cases, it is necessary to measure the rate of reaction in each separate stage, if the rate measurements are to have any significance from the kinetic point of view.* These difficulties cannot be wholly avoided, for at least in some measure they are characteristic of the process of precipitation from solid solution, but they can be minimized both by the selection of a simple system and by the use of a method of measurement relatively free from anomalous behavior. The present paper reports dilatome tric measurements on the rate of precipitation of silicon from the aluminum-rich solid solution in the aluminum-silicon system—a study that approaches the desiderata of simplicity. The aluminum-silicon system offers advantages from these points of view: there are no known anomalies in the property changes accompanying precipitation; there are no known transition stages; the precipitate is an element, not a compound, and both matrix and precipitate are cubic, and while the structures are not identical (the solid solution is face-centered cubic and the precipitate is diamond cubic), the system at least approaches the ideal case of a crystal precipitating from a matrix of the same crystal type—the ideal case which Becker6 assumed in treating the precipitation process theoretically. The dilatometric method, while not free from disturbing effects, as the subsequent dis-

Jan 1, 1943

By Lawrence K. Jetter, Robert F. Mehl

Some advances have been made recently in the theory of the kinetics of precipitation from metallic solid solution despite the complexities of the problem, but there is surprisingly little quantitative information available on rates of precipitation with which to test present theory or upon which to build new theory. Attempts to measure rates of precipitation have been beset with difficulties which originate both in the anomalies that attend the changes in the properties selectcd for measurement, as, for example, in electrical conductivity or mechanical properties, and also in the complexities in the structural changes in some systems, as in the aluminum-copper system. If the functional relationship between the quantity of precipitate and the value of the selected property is uncertain, measurements of that property are obviously of uncertain utility in determining absolute rates of precipitation. If the precipitating system passes through one or more transition stages, the interpretation of measured rates lacks definiteness; in such cases, it is necessary to measure the rate of reaction in each separate stage, if the rate measurements are to have any significance from the kinetic point of view.* These difficulties cannot be wholly avoided, for at least in some measure they are characteristic of the process of precipitation from solid solution, but they can be minimized both by the selection of a simple system and by the use of a method of measurement relatively free from anomalous behavior. The present paper reports dilatome tric measurements on the rate of precipitation of silicon from the aluminum-rich solid solution in the aluminum-silicon system—a study that approaches the desiderata of simplicity. The aluminum-silicon system offers advantages from these points of view: there are no known anomalies in the property changes accompanying precipitation; there are no known transition stages; the precipitate is an element, not a compound, and both matrix and precipitate are cubic, and while the structures are not identical (the solid solution is face-centered cubic and the precipitate is diamond cubic), the system at least approaches the ideal case of a crystal precipitating from a matrix of the same crystal type—the ideal case which Becker6 assumed in treating the precipitation process theoretically. The dilatometric method, while not free from disturbing effects, as the subsequent dis-

Jan 1, 1943

By K. D. Hester, A. W. Fletcher

A nickel-copper sulphide concentrate was treated in a pilot plant at Warren Spring Laboratory during 1961, by a hydrometallurgical roast-leach-solvent extraction process devised to cleanly separate the metal values and produce acid sulphate liquors containing the metals. It is shown that 86 pct of the nickel and 95 pct of the copper could be leached from the calcine, after a sulphatizing roast on finely ground flotation concentrate. Iron was removed from the leach liquor by limestone neutralization with a small loss of values. Copper and nickel were separated by solvent extraction with naphthenic acid in kerosene after partial neutralization of the iron-free liquors with ammonium hydroxide. Hydrogen sulphide and chlorine were used to remove zinc (and residual copper) and cobalt impurities respectively. The recovery of pure copper and pure nickel, by electrowinning, from the acidic solvent extract strip liquors finally produced, appears technically feasible. An economic analysis of production costs shows that small, geographically isolated, nickel-copper sulphide deposits cannot usually be worked profitably by established processes. The requirements for profitable operation on a comparatively small scale could possibly be met by a flotation-roast-leach process. Two difficulties, obtaining satisfactory extraction of nickel from a sulphide concentrate and separating the copper and nickel in solution, have prevented the previous use of this method. A solution to the first problem, dissolution of the nickel, was described in a recent paper by Thornhill.1 It was shown in this paper that copper and nickel in a flotation concentrate could be oxidized to water soluble sulphates by roasting in a fluidized bed with added salt cake. Workers at the Warren Spring Laboratory have shown that the separation of copper and nickel can be accomplished by solvent extraction using a relatively inexpensive carboxylic acid, naphthenic acid. Moreover, the mineral acid required to strip values from the loaded solvent could be produced, and the metals recovered, by electrowinning; thus the latter section of the process was regenerative. The removal of iron from the leach liquor and the elimination of impurities such as zinc and cobalt before nickel electrowinning would be necessary to complete the flowsheet. The process under investigation could therefore be summarized (Fig. 1) as follows: 1) Flotation to produce a bulk sulphide concentrate. 2) Fluidized bed roasting to sulphate the nickel and copper minerals. 3) Leaching of roaster calcine to extract soluble nickel and copper. 4) Precipitation of iron from the separated leach liquor by air oxidation after the adjustment of pH and temperature. 5) Recovery of copper from the iron-free Liquor by pH adjustment and liquid-liquid extraction. 6) Purification of the copper raffinate by removing zinc and residual copper as insoluble sulphides and cobalt as cobaltic hydroxide. 7) Recovery of nickel from the purified liquor by pH adjustment and liquid-liquid extraction. Laboratory and pilot plant studies detailed below, were carried out at the Warren Spring Laboratory, to test the feasibility of each one of the unit processes and to obtain preliminary plant design data. FLOTATION The ore was an altered basic rock containing concentrations of magmatic sulphides.

Jan 1, 1964

By H. L. Marcus, C. D. Turk

Titanium was physically vapor-deposited by electron beam high rate evaporation. Rates of 50,000 and 85,000Å per min at deposition temperatures of 480°, 535°, and 595°C were used. Deposited thickness ranged front 0.004 to 0.010 in. The evaporated titanium had a high degree of basal Plane texture. The specimens were tested in tension at temperatures ranging from 78° to 520°K. From the data, the yield stress, thermal component of the yield stress, and work hardening characteristics were found as a function of temperature, deposition rate, and deposition temperature. It was found that Taylor's equation, best fit the work hardening data with m = 1/2. MANY investigations have been made on the tensile deformation characteristics of commercial- and high-purity titanium.1"7 The data obtained from these experiments emphasize the fact that the mechanical properties are generally related to the method of production. The correlation of mechanical properties to production history arises from the dependence of impurity concentration on the extraction and melting technique used. Additional effects are derived from crystallographic texturing which can result from fabrication history. Lee and Backofen8 and other investigators9 have shown that crystallographic texturing in titanium sheet has a significant effect on the deformation characteristics. Bunshah and Juntz10 prepared high-purity titanium by high rate physical evaporation techniques. These authors found the deposited material to have a columnar structure with grain sizes ranging from 12 to 104 µ, depending upon the substrate temperature. The room-temperature strengths of the coarse-grained distillate were similar to arc-melted, rolled. and annealed crystal bar titanium. Commercial-purity titanium was also produced experimentally in our laboratory using high rate physical vapor deposition techniques. The commercially pure material has a finer structure than the high-purity distillate,10 and is highly textured. Since the method of preparation and degree of texturing affect the mechanical properties, a research program was initiated to determine the temperature dependence of the yield stress and work hardening characteristics as a function of high rate deposition parameters. This paper relates the results of the investigation. EXPERIMENTAL A) Material Preparation. The titanium was received in the form of commercial-grade 0.096-in.-diam wire which has a composition of 0.016 pct C, 0.0037 pct N, 0.110 pct 0, 0.011 pct H, 0.05 pct Mn, 0.051 pct Fe. balance Ti. The wire was continuously fed into a vacuum evaporation unit as shown schematically in Fig. 1. The deposition chamber was evacuated, purged with argon, and reevacuated to a pressure of 10-5 Torr which was maintained during deposition. A focused electron beam was used to evaporate the titanium from a water-cooled copper crucible. The titanium vapor was condensed onto a preheated titanium substrate. The temperature of the substrate was controlled within ±5°C for the deposition temperatures of 480°, 535°, and 595°C. Control of the input power enabled the use of two deposition rates. 50,000 and 85,000Å per min. The evaporated titanium had a final analysis similar to that of the input titanium, within experimental limits. B) Testing. The evaporated titanium was physically stripped from the titanium substrate and machined into tensile specimens with 1-in. gage lengths. In addition, tensile specimens of as received annealed 35-A titanium sheet with a 20 µ grain size and 45 pct cold-rolled 35-A were also prepared. All specimens were tested in tension in an Instron at a strain rate of 3.3 x 10"4 in. per in. per sec. Proportional limit has been used as a measure of yield strength. Tests were conducted at 78°, 220°, 300°, and 520°K. Metallography, X-ray diffraction, and electron microscopy were used to correlate structure with the deposition parameters and mechanical properties. Room-temperature X-ray measurements were made to determine the phases present. Pole figures and a scans were made to determine deposition texture. Because the vapor deposition was symmetrical about the normal to the substrate, there was no preferred di-

Jan 1, 1969

Discussion of the paper of, RICHARD H. RICE, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 89, May, 1914, pp. 721 to 743. S. G. VALENTINE, Oxford, N. J.-In a paper read at the New York meeting of the Institute last February I presented some notes taken from our experience with the turbo blower operating on a blast furnace. In connection with Mr. Rice's very interesting paper there are a few items that might be of further practical interest. The question of the reliability of this type of blower will naturally be presented. In this connection we would say that our turbo blower has been in practically continuous use during the present blast, which was begun June 7, 1912, with only three interruptions for repairs of any consequence. Soon after blowing in there was developed a tendency of the blower to surge or pulsate. This occurred on operating at a point considerably below the normal capacity of the machine, and was checked with comparatively little trouble by throttling the intake slightly and taking up a small lost motion on the governor connections, a legacy of the previous blast that had not been attended to. All this required only a few hours' time. In. March, 1914, the furnace being banked on account of a blizzard that cut off our freight deliveries for five days, the opportunity was used to replace the carbon packing on the steam-turbine shaft and to repack the steam inlet valves. In June, 1914, the blower was off 8 hr. to replace an oil ring and scrape a bearing. With these exceptions we have made continuous use of the machine and find we can depend upon it with entire safety as a piece of machinery.

Jan 4, 1915

By Charles S. Barrett, F. W. Steadman

DEFORMATION bands of surprising regularity are found in large-grained polycrystalline copper after cold-rolling (Fig. I). Individual bands frequently are large enough to permit a determination of their orientation by means of etch pits and an optical goniometer. Measurements have been made on 21 areas in seven different grains, and these, combined with X-ray studies of nine single crystals that had been cold-rolled after mounting in a polycrystal-line block, have contributed to a better understanding of the preferred orientations in rolled copper just as similar studies have for rolled iron' and brass.2.3 Particular attention was given to determining orientations that are stable during rolling and to the manner of fragmentation and rotation of unstable grains. The possible role of twinning was also carefully investigated. The texture of polycrystalline copper after cold-rolling is well established by the pole figures that have been plotted by Schmid and Staffelbach,4 Iweronowa and Schdanow,5 and Brick and Williamson,3 all of which are in substantial agreement. There has been some divergence in the list of individual "ideal" orientations that have been used to describe the texture by these observers and others,6 although the orientation (110) [112]-that is, (110) parallel to the rolling plane and [112] parallel to the rolling direction-is generally recognized as the most prominent orientation and (I12) [111] one of the lesser orientations. Other orientations have been given by some observers as (236) [533], (100) [001], and (I 10) [001]. The texture of copper has also been described as (135) [533].6.1 The sum of these orientations provides a reasonable approximation to the complete pole figure, but it does not follow that these specific orientations are necessarily of fundamental significance, for the choice of indices is arbitrary, within limits. Furthermore, a detailed investigation of the ideal orientations in cold-rolled iron discloses continuous ranges of equally favored positions rather than definite positions of high stability,1 and similarly Brick's observations in a single crystal of a brass2 suggest that all orientations in the range between (110) [113] and (110) [117] are about equally stable. MATERIALS AND METHODS The material used was vacuum-cast electrolytic copper kindly supplied by L. L. Wyman, of the General Electric Co.* Slices 1/2 in. thick and 2 1/2 in. square, cut from the ingot, were rolled with 50 per cent reduction per pass to final thicknesses between 0.02 and 0.04 in., and etched to develop cube-face etch pits suitable for goniometric work.8 The etch was light on some strips and deep in others.

Jan 1, 1942

By J. Leslie Goodier

The International Law of the Continental Shelf, so far ratified by 35 nations, extends the national boundary of any coastal nation to the edge of the continental shelf, this normally being at a continuous water depth of 200 m. The Law further extends this boundary to include the floor of the deep ocean to any depth that can be mined by advanced mining technology. In effect, proof of mining can constitute proof of ownership of the subaqueous land and the minerals on or below the sea floor. Irrespective of the fact that present technology is too limited to permit mineral exploitation in the high seas-and the law regarding the right to mine appears hazy-the U. S. Treasury Department's Bureau of Customs, has a ruling that would further deter mining operations on the high seas. This law contends that minerals mined on the continental shelf of the United States are actually mined within the continental United States and are free of tariff, but mined products or other articles obtained from the ocean or the sea floor beyond the continental shelf, if brought into this nation, must be considered as imported and are subject to such customs duties as are applicable under the tariff schedules of the United States.

Jan 7, 1968

By E. W. Davis

THE large iron-ore producers on the Mesabi Range are able to maintain the silica in their shipping products at from 8 to 10 per cent by mixing ores of various grades, some assaying 4 per cent silica and some as high as 18 per cent silica. For each ton of 4 per cent silica ore mined, a ton of 14 per cent silica ore can be mined and mixed with it and the average grade maintained at 9 per cent. This mixing operation has made possible the utilization of large cluantities of ore too lean to be used alone. and herein lies the advantage of the producers who operate a number of mines at the same time. As the grade of the ore from one of the properties falls off, a little high-grade ore from another property can be mixed with it and the average maintained, while if one property alone were being operated all of the ore below grade would be left behind.

Jan 1, 1930

By S. Jana, C. M. Wayman

The reverse transformation of bcc martensite to the fcc phase was studied in an Fe-33.95 wl pct Ni alloy by nzeans oj dilatometry, melallography, and electron microscopy. Upon "slozc" heating (-1°C per min) length cJmnge us temperature plots showed u gradual contracLion over the temperature range 200" to 280"C ,followed by a more abrupt contraction beginning a1 -280°C. Howet,ev, zchen the heating rate was increased -4°C per tnin, no gradual contraction was observed and only the abrupt contraction starting at -2BO"C was found. Thus on slower heating- the AS "temperature" for the subject alloy, unlike the MS temperature, is better defined as a range of temperatures. Both optical and transmissiorl electron microscope observations showed that some of the martensite plates exizibited a partial loss of transformation twins during reversal. The midvib region of the martensite plates disappeaved relatively early duirng the reversal. Metallographic observations slowed that the earliest detectable stage of the rezlerse tvansforrvration begins (axd Moues inulardly) at The Martensens i te - parent interface. At higher temperatirres, the. formation of martensitically reversed jcc plates within the bcc martensite plales was observed. It is concluded that the reverse transformation consists of a diffusion less process (martensitic); but this is ps-obably aided by a prior or simultaneous dijjusiorz-comltvolled process, at leasl in the case of slower heat-ing' experiments. ALTHOUGH numerous investigations have dealt with the parent-to-martensite ("forward") transformation (fcc — bcc) in Fe-Ni alloys, comparatively little is reported on the ("reverse7') martensite-to-parent transformation.'-4 Even though such reverse transformations have been studied in detail in some nonferrous systems, one of the difficulties of studying the reverse transformation in most ferrous mar-tensites is that the martensite decomposes by tempering during heating. However, carbonless Fe-Ni alloys do not exhibit this difficulty since the transformation in these alloys is completely reversible. The present investigation represents an attempt to shed more light on the nature and mechanism of the martensite-to-parent transformation. 1) EXPERIMENTAL PROCEDURE 1.1) Alloy Prepatation. Fe-Ni alloys of compositions near 34 wt pct Ni were prepared from zone-refined iron (99.994 wt pct Fe) and high-purity nickel (99.999 wt pct Ni) by induction melting in recrystallized alumina crucibles in an argon atmosphere, with prior vacuum evacuation to 10"3 mm Hg. The alloys were homogenized by induction stirring in the molten state for 5 min. After solidification, the alloys were further homogenized in evacuated quartz capsules for 96 hr at 1230°C. 1.2) Dilatometry. Slices of the ingot were hot-forged (750°C in air) into approximate rod form and these specimens were then hot-swaged (750°C in air) into long cylindrical rods 0.55 mm diam. From the rods, specimens about 1 in. long were cut. These were then vacuum-annealed for 24 hr at 1200°C, cooled to room temperature, and subsequently transformed to martensite in liquid nitrogen (whereby about 40 pct transformation was obtained). Dilatation measurements were made by observing length changes in a vacuum dilatometer with an externally mounted LVDT sensing element. 1. 3) Preparation of Electron Microscope Specimens. Slices of the ingots were cold-rolled (with intermediate vacuum anneals) to -0.020 in. Out of these rolled sheets, specimens (about 1 by 1 in.) were cut. These were then vacuum-annealed, transformed to martensite by cooling in liquid nitrogen, and subsequently heated from room temperature to various temperatures to effect either partial or complete reverse transformation. These specimens were then chemically polished to 0.002 in. in l:l HsOz (30 pct) and &PO4 (85 pct) solution, and thinned to electron transparency in an electrolyte consisting of 150 g CraOs, 750 ml glacial acetic acid, and 30 ml ~~0.~ Observations were made with a 100-kv Hitachi HU-11 electron microscope equipped with an HK-2A tilting device. 1.4) Optical Microscopy. Metallographic observations were made with a Leitz MM5 metallograph on the same 0.020-in. sheet specimens as were used for electron microscopy and on bulk specimens which were 0.2 in. or more on a side. The chemical thinning solution when cooled below 20°C also served as an etchant for this alloy. Observations of surface relief were made with a Zeiss interference microscope employing a Thallium light source of wavelength 0.54 p. Specimens for interference studies were prepared by two-stage polishing on Buehler vibromet polishers using 0.3 and 0.05 p alumina abrasives. 2) EXPERIMENTAL RESULTS 2.1) Comparison of the MS,AS, and Af Tempera-tures wTth Previous Re sults. The AS aLd Af tempera -tures of several Fe-Ni alloys were determined dila-tometrically. The MS temperatures of the same alloys were determined by continuously lowering the temperature using a mixture of isopentane and liquid nitrogen and observing the highest temperature at which a prepolished specimen showed surface upheavals. For the present the As temperature is defined as the temperature at which an abrupt decrease in length occurs in the dilatation plot. The Ms,As7 and A determinations in the present investigation and those of Kaufman

Jan 1, 1968

Steps were taken for a permanent organization of the scientific and technical employees of the Government at their mass meeting on May 8. This was the result of an informal meeting on Apr. 23 of thirty representative Government scientists and technical men who organized the preliminary committee and called the mass meeting. This subject has been widely discussed during the last year and was brought acutely to the fore by the work of the Joint Congressional Reclassification Commission, because that Commission has stated that it wished to deal with employees only through organizations. Rodney H. True of the Department of Agriculture was Acting Chairman. He pointed out that the principal advantages that were expected to be derived from such an organization were: (1) Improvement of conditions and facilities for more effective scientific and technical work; (2) adequate presentation of the needs. and results of such work to the public and to legislative and administrative officers; (3) -greater freedom in both official and non-official activities; (4) just and reasonable salaries based on service performed and the economic and social conditions which prevail; (5) greater public recognition of the aims and purposes of research; (6) advancement of science and technology as an essential element of national life. Three plans of organization were offered to the meeting, which covered the fundamental principles which could be utilized by these Government employees. The first plan would have permitted the new organization to work only through existing scientific organizations. This is the plan that scientific and technical Government employees in England have adopted and an outline of the English plan was read to the meeting.

Jan 6, 1919

By G. R. Fitterer

NONMETALLIC inclusions in steel have received much attention by metallurgists during the past few years. Many investigators have been emphatic in stating their belief that these impurities are the chief causes of steel failures, while others think that their effects are negligible. One of the main reasons that definite information on the effects of these impurities is lacking is that no reliable method has been developed for the exact determination of the amounts of these different impurities in steel. Some valuable new information has been brought out by a reliable method for nonmetallic inclusions which has been developed at the Pittsburgh Experiment Station of the U. S. Bureau of Mines, in cooperation with the Carnegie Institute of Technology and the Metallurgical Advisory Board. This procedure satisfactorily extracts some of the more common inclusions from steels, thus enabling the investigator to correlate steel failures with inclusion content. Although the data given herein are the first to be published on the subject of the electrolytic extraction method, the interest in the subject is evidenced by the fact that it is already being used by some 20 to 30 steel companies for their various purposes. Some of the comments received from these laboratories indicate that the method is highly satisfactory: the unfavorable comments, when traced to their sources, have been found to be based on some small mistake made in either installation or operation. The chief discrepancy seems to have occurred in attempts to apply the method to the extraction of inclusions from alloy steels. The procedure can be used only for the plain carbon steels and for such low alloy steels as those containing the usual amount of copper (0.2 to 0.3 per cent). Steels containing the carbide-forming alloys such as chromium, tungsten, etc., present far too many difficulties for the accurate determination of inclusions. Luckily, the iron and manganese carbides do not offer any difficulties and no contamination of the oxide-sulfide residue results. It is highly probable that some modification of the following

Jan 1, 1931

By R. W. Winson

Asbestos is the generic name given to a group of fibrous mineral silicates found in nature. They are all incombustible and can be separated by mechanical means into fibers of various lengths and cross sections, but each differs in chemical composition from the others. The commercial grades of asbestos consist of a spectrum of lengths and sizes and are not definitive as are most organic fibers. It is generally recognized that there are two main groups of asbestos. The first only contains the fibrous serpentine called chrysotile and comprises about 94% of the world production of asbestos. The second group contains five minerals in the amphibole series+rocidolite, amosite, anthophyllite, tremolite, and actinolite. The latter two have no commercial importance. Properties Physical The structures of asbestos fibers have been studied intensively over a number of years. X-ray diffraction patterns have been used as a means of identification and classification. Low angle X-ray scattering techniques have shown that chrysotile fibers are "hexagonally close packed" and parallel to each other, having cross-sectional diameters varying from 18014 to 300A units, while the amphibole fibers are many times larger in cross section. Electron micrographs of the more common types of as- bestos are shown in [Figs. 1-4]. [Fig. 1] illustrates the softness and flexibility of chrysotile which make it suitable for textile-type products. For a number of years there was considerable controversy over the exact nature of chrysotile fiber, but the photographic evidence in [Figs. 5-7] clearly show that it is tubular in structure. The curvature is the result of the mismatch in the dimensions of the silica [Si,O,l and brucite [Mg(OH),] layers which are on the inside and outside, respectively, of a double sheet. This curvature had been predicted by Pauling (1930) years ago based on the molecular dimensions of the two component structures.

Jan 1, 1975

By A. J. Jacobs, G. Katz

MANY of the studies of intermetallic compounds containing uranium were performed during the early 1940's under the aegis of the Manhattan Project. Subsequently, much of this work was declassified and published after 1949. In some instances this early work, completed with relatively impure materials, represents the only source of X-ray diffraction powder data available in the literature. In the case of the intermetallic compound U,Fe some discrepancies in the powder pattern exist in the literature. Since this compound has been prepared in this laboratory, it is believed that the publication of the indexed powder pattern would help clarify the conflict in the literature. In studies of the U-Fe system, Gordon and Kauf-mannl and Grogan and Clews2 independently reported the intermetallic compound U,Fe in 1950. The crystal structure was described by Baenziger, Rundle, Snow, and Wilson3 in 1950. It is isostructural with U,Mn, U,Ni, and U,Co and crystallizes in a body-centered tetragonal lattice. The lattice constants determined by Baenziger et al. are: giving an X-ray density = 17.7 g cm-3 for 4 mol per unit cell. The compound used in this study was prepared by melting a stoichiometric mixture of the constituent metals in an argon-arc furnace using a nonconsum-mable tungsten electrode. Before the argon of 99.98 pct purity was introduced into the furnace, it was passed through CaC1, to remove water vapor and afterwards through a stainless steel tube containing calcium turnings heated at 600°C for the removal of nitrogen and oxygen. The purity of the uranium used was better than 99.9 pct and that of the iron was 99.97 pct. Before and during melting a zirconium getter was used to further purify the argon atmos-

Jan 1, 1962

By John Kafritsas

INTRODUCTION Deformations and failure of rock masses in elopes, foundations or tunnels can be caused by water pressures. On the other hand, deformations of a rock mass affect the flow of water (and hence water pressures) by changing joint apertures. Including the coupling between flow and deformation effects is therefore important both in assessing the stability and deformation of a rock mass and in determining the amount of seepage taking place through it. The model that will be presented hare treats the coupling of the flow and deformation behavior of a rock mass. Deformations are modeled using the Rigid Block Method (Distinct Element Method) (Cundall, 19741, that is by assuming that the rock mass is composed of rigid blocks with deformable contact points. Flow is modeled by recognizing its discontinuous features, as occuring in a system of interconnected conduits formed by the joints. The program can also deal with problems involving free-surface flow. Example problems involving representations of rock masses are presented. Coupled flow modeling of interconnected conduits should be contrasted to equivalent-continuum models on the one hand and to pipe network models on the other hand. Continuous models substitute an anisotropically permeable continuum for the discrete flow that occurs in rock joints. Pipe or parallel plates represent the other extreme of existing models; they account for the discontinuous character of the flow problem, but cannot model rock mass deformation and failure. The coupled rigid block-flow model can eliminate most of these restrictions. The coupling between water flow and deformation is most pronounced in rock masses which, because of the arrangement of their

Jan 1, 1984

By K. P. Gupta

The Cb-rich boundary of the (Cb,Al) a phase field at 1250OC is near 41 pct Al. The Al atoms tend to occupy the C. N. 12 sites in this structure. A homologous (Ta,Al)a phase was identified. No a phase was found in the Mo-Al system at 1200°C. The first binary o-phase with a non-transition element as a major component was found1,2 in the Cb-Al system. The composition of this phase was reported2 as approximately 34 at. pct Al, based on X-ray diffraction patterns taken of alloys in the as-cast condition. Further study of the composition of this o-phase, therefore, appeared desirable. Since Si was previously found3,4 to occupy preferentially the lowest C.N. sites (I and IV) in the a phase, and preliminary resultsa indicated that Al may show similar ordering, one of the aims of the present work was to obtain more complete information on ordering in (Cb, Al) o. Among the binary systems of Al with Ti-, V-, and Cr-group elements, the Ti-Al, Zr-Al, V-Al, and Cr-Al systems are known to comprise no o-phase. In the present work a Ta-Al and a Mo-Al alloy were studied in an effort to find additional o phases with Al as a major component. EXPERIMENTAL PROCEDURES AND RESULTS An alloy with the intended composition of Ta + 40 at. pct Al was prepared by arc melting in He atmosphere. In both the as-cast condition and after annealing for 10 days at 1250°C and quenching in cold water this alloy consisted of two phases, as seen in the X-ray pattern and the microstructure. One of these phases was identified as the o-phase; the observed and calculated d-spacings are shown in Table I. The lattice parameters of this o-phase are a = 9.972 A, c = 5.214 A and c/a =0.5228, as determined from a Debye-Scherrer pattern using Fe K a radiation. The d-spacings for the unknown second phase are given in Table 11. The alloy contained approximately 25 pct of the unknown phase after annealing, as estimated on the basis of microscopic examination. A Mo-Al alloy was prepared by arc melting, with an intended Al-content of 35 at. pct. The alloy button was annealed for 7 days at 1200°C and water quenched. The X-ray pattern of the alloy in both the as-cast and the annealed state showed the reflections of Mo3Al (Cr30 type structure) and an unknown phase different from a. Six Cb-Al alloys were prepared in the composition range 30 to 50 pct Al. All alloys were arc melted in He atmosphere. After annealing for three days at 1175oC in evacuated silica capsules and quenching in water, the alloys with 30 to 40 pct Al contained three phases, namely the o-phase, Cb3Al (Cr3O-type structure) and an unknown phase. The alloys with more than 40 pct Al contained two phases, namely, what appeared metallographically, the o-phase and the same unknown phase. In the alloys containing less that 38 pct Al, the unknown phase was not present after annealing for 4 days at 1250°c,

Jan 1, 1962