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By Worthen Bradley

A BETTER understanding of what is happening in the domestic quicksilver industry, and what is likely to happen, can be had after reviewing some of the highlights of the past four years. Hitting the high spots in chronological order, they are: February 1939-Army and Navy Munitions Board starts investigation on civilian and war needs of certain "strategic materials," including quicksilver, with a view to recommending stock piles. Every known producer is canvassed by the end of the year.

Jan 1, 1942

By W. A. Backofen, B. B. Hundy

THE pole figure interpretation in a recent paper' on the torsion texture of copper was questioned in discussion,2 nd a simpler alternative interpretation was proposed. In the hope of reaching a positive decision in favor of one or the other, further studies were undertaken with 70-30 brass and Armco iron. This additional work has not answered all the questions about torsion textures, but the new pole figures do offer support for the original interpretation and show that the texture is more complicated than the alternative suggests. From the previous paper,' the appropriate method of describing the texture in a twisted bar is known to be a pole figure plotted on a plane tangent to the surface of the bar. The axes of the pole figure are chosen to coincide with directions in the tangent plane which are parallel and at right angles to the bar axis (the longitudinal direction, L.D., and the transverse direction, T.D.), for these directions define symmetry axes of the texture. Therefore any ideal orientation that might be selected to represent the texture gives the crystallographic plane parallel to the tangent plane and the crystallographic direction parallel to the axis of the torsion specimen. A unique texture was assumed in the original interpretation, and the four ideal orientations, (112) [111], (111) [112], (110) [001], and (112) [131], were used in its description. Of the four orientations, the first three provide possible slip directions along the direction labeled T.D. in the pole figure, which is one of maximum shear stress in a specimen being twisted. The alternative, however, simply considered the texture to be made up of two components, one a [Ill] alignment along the specimen axis with a random orientation about the axis as in the wire texture, and the other a superimposed orientation (110) [0011. Experimental evidence for this simpler interpretation was derived from two observations: 1—twisting did not alter the orientation of a single-crystal torsion specimen of a brass in which an octahedral plane was perpendicular (and a [Ill] direction parallel) to the axis, and 2—deformation bands with approximately the (110) [001] orientation were seen to develop in the crystal during the test. The new pole figures were obtained with a brass and an iron torsion specimen of 3/4 and 1 in. gage length diameter, respectively. After annealing, polishing, and twisting, seven rods, about 0.030 in. in diameter and with different orientations, were prepared from material near the surface of each specimen; these were required for the method of constructing pole figures by using a Geiger counter as developed by Norton.5 Since the shear strain gradient in plastic torsion is linear, it was readily computed that the material supplying the brass rods had been subjected to a shear strain of about 3.2, and that supplying the iron rods had received a shear strain of about 2. All details concerning specimen design, testing procedure, rod preparation, and use of the Norton technique can be found in ref. 1. Only this procedure was followed in working out the (111) and (100) pole figures for brass, Figs. 1 and 2. However, X-ray photograms were also involved in the construction of the (110) pole figure for Armco iron, Fig. 3. The photograms were made according to the conventional transmission diffraction technique using a small sheet taken parallel to the specimen surface and etched to a thickness of about 0.0025 in. They were especially important in locating the boundaries

Jan 1, 1954

THE metal iron has physical and chemical properties which are somewhat different from those of steels, but a knowledge of the pure metal is a useful starting point in studying the behavior of steels. Solid iron exists in two different crystalline forms, called alpha (a) and gamma (?) iron, the former being the ordinary form at room temperature. When heated above the "A2 point," 1400°F. (760°C.), the metal becomes non-magnetic, and at the "As point," 1670°F. (910°C.), it undergoes a change in crystalline form to become gamma iron. In the range 1400 to 1670°F., it is sometimes called beta (0) iron to distinguish it from the magnetic alpha, but the two are identical in crystal structure. When gamma iron is further heated to 2550°F. (1400°C.), it changes into delta (d) iron, which is identical with beta or non-magnetic alpha iron. Pure iron melts (in a hydrogen atmosphere) at 2795°F. (1535°C.); the melting point is generally lowered by alloys or impurities. PROPERTIES OF IRON AT HIGH TEMPERATURES Many of the properties of iron undergo abrupt changes at the transition temperatures. (1) For example, in heating through the As point a sudden shrinkage in volume occurs. Similarly, melting is attended by sharp physical changes such as an increase in volume. Table 27 contains a summary of the measured physical properties of pure iron at several temperatures. Usually the properties change smoothly within the range of stability of a given form, but this is not always the case. For example, the specific heat reaches a sharp maximum at the A2 point although no transformation occurs. Solvent Powers of Liquid Iron. Liquid iron is capable of dissolving most of the other metals and many nonmetallic elements as well. Of the metals which are liquid at the melting point of iron only lead, silver, and bismuth refuse to dissolve to an appreciable extent. The non-metals presumably dissolve by virtue of the formation of an iron compound; for example, sulphur is thought to dissolve as the compound FeS. However, there is no satisfactory method of proving that this

Jan 1, 1944

By J. D. Meakin, H. G. F. Wilsdorf

Using a combined decoration and etching technique the dislocation structure of annealed and deformed a brass has been studied. Annealed crystals revealed a low density forest and well-developed subboundaries; lightly deformed crystals contained discrete groups of dislocations. The dislocation density and the number of dislocations in a group were obtained from the micrographs. Using slip-line data, the mean path of a dislocation and the configuration of groups along an active slip plane have been deduced. Observations on secondary and cross-slip are reported. It has been the aim of many investigations to obtain detailed knowledge of the dislocation patterns which are present in metals before and after their deformation. The "decoration" of dislocations with impurity atoms has been considered as one of the promising experimental approaches, and much work has been done to develop this technique for revealing dislocation sites in metals. Following the early work by Castaing,' Castaing and Guinier,' and Lacombe and Berghezan~ on aluminum-rich aluminum-copper alloys, dislocations in this material have been studied extensively by others.+' In these alloys the dislocation sites act as nuclei for the precipitation of the second phase. The main results of the investigations on aluminum with copper are: i) the confirmation of the earlier contention that subboundaries consist of dislocation walls, ii) that many more dislocations are found in slip bands than in regions where less glide had taken place, iii) the observation of individual dislocations, lying nearly parallel to the surface investigated, and iv) that parts of dislocation loops, apparently emitted from a dislocation source, could be made visible. Recently, Jacquet, Weill, and Calvert have succeeded in revealing nearly concentric dislocation loops in quenched A1-4 pct Cu and thus indicated directly the existence of dislocation sources in a fcc metal specimen of normal dimensions. Another decoration method developed by Dash10'11 and applied to silicon crystals makes use of diffusing copper to the dislocations from a surface deposition. The dislocation pattern can then be observed by an infrared technique. His results include evidence for symmetrical and spiral Frank-Read sources, and for arrays of dislocation loops which follow simple crys-tallographic directions. Recently Low and Guard" have studied the dislocation structure of silicon-iron using carbon for the

Jan 1, 1961

By E. S. Machlin, S. Weing

GRAIN boundary stress relaxation has been the subject of several investigations in recent years, but as yet the phenomenon is not well understood. One of the major difficulties has been the lack of a sufficient amount of data with which to evaluate any proposed mechanism. Little information is available on the effect of small amounts of substitutional solutes on grain boundary stress relaxation. It is with this important phase of the problem that this investigation is concerned. The influence of substitutional solutes on grain boundary stress relaxation has been recently investigated in copper by Pearson: and in aluminum by Dorn et al.' Pearson studied the effect of zinc, gallium, germanium, and arsenic on the relaxation peak of OFHC copper.* The pure OFHC copper decreased the peak intensity and a second peak appeared at a higher temperature. This latter peak was termed the alloy grain boundary peak. At the lowest binary concentration studied, approximately 1 atomic pct, the primary peak was almost completely obliterated. Pearson found that the activation energy calculated from the alloy grain boundary peak for all solutes, irrespective of the concentration, was 44,000 cal per mol. Pearson concluded that the increase in activation energy from 33 to 44 kcal per mol is not continuous but abruptly changes from the lower to the higher value. As no attempt was made to investigate the intermediate range of concentration and hence calculate the possible variation of the activation energy for the initial grain boundary peak, this conclusion is hardly valid. In contrast to these results, Dorn et al. studied the effect of zinc, silver, copper, germanium, and magnesium on the grain boundary stress relaxation of aluminum. No change in the energy of activation was observed for binary alloys of the flrst four solutes, but a linear increase was found for increasing concentration of magnesium. Saturation was not found up to the maximum of 1.6 atomic pct. The energies of activation were obtained by plotting the horizontal displacement of the dynamic modulus curve vs temperature for two vibrational frequencies. As the modulus is proportional to the square of the frequency, this requires the measurement of the torsional frequency over a range of temperature. However, the technique does not lead to an unambiguous interpretation of the grain boundary

Jan 1, 1958

By W. N. Lacey, B. H. Sage

THE results of an extensive experimental program relating to the effectiveness of gravel screens have been correlated. The factors considered in some detail include gravel size and condition of packing, sand size and size distribution, fluid velocity, fluid viscosity, and thickness and arrangement of gravel screens. Good agreement between calculated values based upon probability considerations and experimental results relating to the influence of the thickness of the gravel screen was obtained. All of these factors are treated in the correlation in order that their influence may be taken into account in ascertaining the characteristics of an effective gravel screen for a particular set of conditions. The details of the experimental program are not given in the present paper but a description of generalized behavior and typical experimental results are recorded in graphic form. INTRODUCTION Gravel screens have been placed in water and oil wells for a number of years1,2,3 with the dual objective of increasing the productivity and decreasing the entrance of sand into the well bore. An understanding of the factors controlling the effectiveness of gravel screens in this connection is of industrial interest because it will lead to the proper selection of gravel. Some of the fundamental considerations involved in the migration of sand through a coarser body of porous materials were investigated by Coberly and Wagner4 and further experimental work has been carried out by Gumpertz.5 Apparently the pertinent phenomena are somewhat complex and are influenced by many variables. The present paper deals with the prediction of the behavior of gravel screens under the conditions encountered in practice but does not attempt to discuss the experimental methods or results that were obtained as a background and upon which the prediction is based. INFLUENCE OF GRAVEL SCREENS UPON PRODUCTIVITY The use of a gravel screen may increase the productivity of a well by increasing its effective diameter, and this constitutes one of the objectives of its use. The permeability of most gravels and coarse sands that are employed in practice is so large compared to that of the sand in place that relatively little loss in production rate will arise from the use of material fine enough to cause the desired resistance to sand migration. For example, in Fig. I is depicted the approximate variation in the permeability of closely sized spherical gravels under the conditions of packing likely to be encountered in screens. The dotted lines indicate the variation that might be found because of differences in packing. It should be realized that the permeability is not a single-valued function of the. average grain diameter but is related to a large number of factors, including the size, the size distribution and the shapes of the particles. However, Fig. I does permit a rough estimation of the permeability of closely sized- spherical gravels and shows that the permeability with even the smaller particles is very large compared to that of most petroleum production horizons.

Jan 1, 1941

In reply to inquiries and comments which have reached me since the publication of this paper, and in explanation of some seeming discrepancies between my statements in the text concerning the amount of displacement of the faults, on one hand, and certain figures in the plates on the other hand, I give here, with some additional remarks, my measurements of the displacements in the different sections, which it originally seemed unnecessary to print : By displacement, I mean neither the throw, i.e., the vertical distance apart of the two edges of a faulted bed (what Mr.

Jan 1, 1896

By W. B. HILLHOUSE

AN excerpt from the Alabama State Mining Law, pertaining to, transporting men' into and out of the mines, reads as follows: "A trip of empty cars may be operated for the purpose of taking employees into and out of the mine, where the distance to and from their work exceeds one mile." The State Mining Department of Alabama includes in its inspection the transportation of men into and out of the mines, also studying and noting improvements, or progress made, that would tend to create a greater assurance of safety in this practice. Everyone is familiar with the original safety methods employed in man-trip transportation, such as passing a rope around the trip of cars, or through the cars, fastened in the conventional manner, and with the usual "clog," commonly called a drag, on the rear end. Also there is a more advanced method of transporting men, such as the double-rope system, which is feasible on slopes used exclusively for this purpose, and is very satisfactory. However, for the past eighteen months; the Republic Steel Corp. and the Tennessee Coal, Iron & Railroad Co. have adopted a practice that shows

Jan 1, 1935

By R. H. Tien

Temperature distribution as well as position of the solidified front is solved by means of "heat balance integral", for the case of freezing a slab with time-dependent surface temperature. Numerical solutions for the cases of linear variation and exponential decay for surface temperature are given. Application also includes solidification of casting. An increased interest in the heat-transfer problem involving a change of phase has been developed in recent years. Practical problems include solidification of a casting, freezing and thawing of soil, ice formation, and others. Despite the importance of the topic, a literature search reveals relatively few solutions which may be extended to practical problems. Due to mathematical complexity, which comes from the nonlinearity of governing differential equations, exact analytical solutions which have been published are limited to a few cases with simple boundary conditions. Although numerical solutions of these problems have become available after highspeed digital computers were introduced, lack of simple and general methods of programming for computation makes this approach impractical. The case of the semi-infinite slab with constant surface temperature was solved in the 19th century. In honor of Neumann, who first found an analytical solution, this kind of problem is generally referred to as the Neumann solution. As has been shown in Fig. 1, the problem to be analyzed is the freezing of a semi-infinite region (x > 0) which is initially liquid at the melting temperature with the surface (x = 0) maintained at time-dependent temperature. This analysis can be applied to the study of many casting processes where most of the heat removal is essentially unidirectional. "Heat balance integral" which has been used by Goodman1 is employed in this analysis. The concept of "heat balance integral" is to define a quantity, d(t), called the thermal layer. Beyond this thermal layer, for all practical purposes, there is no heat transfer, and the region is at the equilibrium temperature. "Heat balance integral" is obtained by integrating the conduction equation with respect to the space variable over this thermal layer d(t). Choosing some plausible temperature distribution, usually a polynomial or a finite trigonometric series in the space variable, this integral equation becomes an ordinary differential equation, with time as the independent variable, which can be solved by classical methods. The thermal layer and "heat balance integral" are equivalent, respectively, to the boundary-layer thickness and the momentum integral in hydrodynamics. A modern account of Prandtl's concept of the boundary layer and von Karman's momentum integral may be found in Ref. 2. Although the problem considered here has been limited initially to uniform melting temperature, the present method is equally applicable to the case with arbitrary temperature distribution in the liquid. STATEMENT OF THE PROBLEM The physical situation and coordinate system used in the problem to be analyzed are shown in Fig. 1. Notations used are listed in the table of nomenclature. Let us assume a semi-infinite region extending over positive x, initially at the uniform melting temperature. At the surface x = 0, a time-dependent temperature, which has a numerical value

Jan 1, 1965

By J. J. Gilman, T. A. Read

FOLLOWING the deformation 01 zinc monocrys-tals, sharply bent basal planes are observed near several types of inhomogeneities. Three of these in-homogeneities have characteristics which are quite regular so that they can be studied and analyzed. These are compressive kink bands, "deformation bands," and the inhomogeneities near end restraints. The present paper describes experiments in which "deformation bands" were artificially produced, and bend plane phenomena are discussed in terms of dislocation theory. Also, two new bend plane phenomena are described. The importance of bend plane phenomena in the deformation of crystals is not widely recognized. Many phenomena may be explained in a manner similar to the discussion in this paper. Jillson1 has pointed out that the "punching effect" in zinc is a bend plane phenomenon and is not caused by prismatic slip.' Bowles3 has suggested that they may be involved in diffusionless phase changes. Cahn4 has discussed the role of bend plane formation in the polygonization of zinc. Experimental Work Tensile Kink Bands: Because of the geometrical similarity between "deformation bands" and "kink bands" (compare Fig. 1 of this paper with Fig. 1 of the paper by Hess and Barrett"), the band shown in Fig. 1 of this paper will be called a "tensile kink band," and that shown by Hess and Barrett will be called a "compressive kink band." It is felt that the term "deformation band" should be reserved for banded structures in polycrystalline materials such as iron." Tensile kink bands seem to form spontaneously in aluminum crystals deformed by tensile loading.7-10 In zinc and cadmium crystals they do not form in good, carefully loaded specimens.'." However, tensile kink bands can be produced artificially in zinc crystals. The present authors did this by scratching one of the flat surfaces of triangular crystals transversely with a sharp needle. Natural tensile kink bands caused by inhomogeneities sometimes appeared in deformed crystals which were identical in appearance with the artificially produced ones. Zinc monocrystals were grown by the Bridgman method in graphite molds. Chemically pure zinc (99.999+ pct Zn) was used and the molds were sealed inside evacuated pyrex tubes during growth. The crystal cross sections were equilateral triangles with a typical base of 0.210 in. The artificial kink band shown in Fig. 1 is typical of tensile kink bands in zinc. The band lies between two bend planes which run from upper right to lower left and is inclined oppositely to the slip bands which are sharply bent at the two bend planes. The general form of the artificial tensile kink bands was independent of the scratch depth (1 to 5 mils deep) and also independent of which side was scratched. These variables did cause variations, however. Deep scratches produced more localized kink bands than light scratches. Also, if the angle between the slip plane traces and a transverse scratch varied appreciably among the three sides, then localization of the resulting kink bands also varied. Furthermore, if the slip direction lay nearly parallel to the scratched side, the band was more developed near the scratched side than at the opposite edge. Scratches produced tensile kink bands for crystal orientations from xo = 15" to x, = 75". Fig. 2 shows a scratched crystal after deformation. One triangular side lies in the plane of the photograph. The right hand tensile kink band was produced by a transverse scratch on the upper right side. The next two kink bands were the result of scratches on the front surface. The kink band at the left was caused by a scratch on the lower back side. All four bands have the same general form. A longitudinal scratch was also made on the crystal shown in Fig. 2 to determine the effect of a scratch on the critical shear stress. The critical shear stress of the scratched region was 33.9 g per sq mm compared to 24.4 g per sq mm for the un-scratched region above it. Fig. 3 shows Laue patterns of the crystal shown in Fig. 2. Fig. 3a shows the pattern of the undeformed crystal. The orientation was x, = 21°, A, = 31". After deformation, Fig. 3b was made of the homogeneously deformed portion of the crystal. The spots are compact but split into two halves. This region was elongated 45 pct and its orientation was x = 14", X = 20"; the sine law predicts x = 14", A = 20.5". Fig. 3c was taken near the center of the middle tensile kink band of Fig. 2. The pattern shows a range of orientations and polygonization in this region. The spread in orientation was due to the fact that the basal planes were curved (see Fig. 1) rather than flat as in the ideal case. Some may also have been the result of elastic distortions and "local curvatures." The orientation range was x = 23" to 32", A = 30" to 42". It is apparent from Fig. 3 that the material inside and outside the kink band rotated in opposite directions with respect to the tension axis during deformation. The orientation calculated from the ideal configuration of Fig. 9,

Jan 1, 1954

By Donald L. Katz

The compressing of gas into a partially depleted gas drive oil reservoir to bring the contents to a single phase miscible with gas is proposed as a process worthy of serious study. The compressed gas and vaporized oil would be recovered by cycling. This paper explores the Possibility of recovering oil from reservoirs of 6,000 ft or more by this method. INTRODUCTION Many new methods for increasing the recovery of oil from reservoirs are under consideration in the various research laboratories. One method which should be considered for recovering oil From partially depleted gas drive fields is to compress gas into the reservoir until the contents become a single phase miscible with more gas. Natural gas then may be cycled through the reservoir to recover the oil. This procedure ideally will eliminate the capillary effects of the liquid ill the porous media and should permit recoveries similar to those obtained in cycling operations, probably of the order of 80 per cent. This paper explores the information now available for the prediction of the performance of such a project and discusses the problems likely to be encountered in recovering oil by cycling. For many years dry natural gas has been passed through oil reservoirs to recover natural gasoline which would vaporize from the oil. Recently a process of recovering more of the high boiling hydrocarbons has been described by employing high pressures at which the heavier hydrocarbons have a higher volatility. Nevertheless. this reported method does not eliminate the differential nature of the vaporization process and capillary forces are still present in the reservoir. The process under discussion in this paper would minimize differential vaporization and would remove capillary forces which are responsible for low oil recoveries. Higher gas pressures are required to accomplish this removal of the miniscus, but it does not follow that more gas is required for oil recovery. The process is limited to reservoirs deep enough to permit the use of the required pressure — Probabably 6,000 it and deeper. DESCRIPTION OF THE PROCESS Briefly, the process is to compress natural gas into an oil reservoir which is partially depleted so that it has an oil saturation in the range of 40 to 60 per cent of the hydrocarbon pore space. The injected gas will pass through the channels formerly carrying gas to the wells to build up the pressure and dissolve in the oil phase. This injection will continue without production from the field until the reservoir reaches a single phase. If one were to select unique conditions such that the gas composition, the reservoir oil composition and the Per cent saturation would bring the mixture in the reservoir to the critical temperature and pressure simultaneously the phase behavior accompanying injection is shown by Fig. 1. The oil-gas mixture in the depleted reservoir has a critical temperature at C,. Addition of natural gas to the mixture will give a new critical temperature for each addition. Mixture No. 3 is shown to have its critical temperature at the reservoir temperature and reservoir pressure at P: the critical pressure. Under ideal behavior, the entire reservoir would be at iti critical temperature and pressure and the entire hydrocarbon content would be at a single phase. If the reservoir content were a binary system of methane and a heavy constituent. it would be miscible with more methane. However, for complex mixtures the critical locus does not confine the two phase region, and the dew point curves of Fig. 1 occur above the critical locus. If fluid which was injected into the rezervoir at the critical point were of the

Jan 1, 1952

By G. W. P. Rengstorff, R. B. Fischer

A study was made of the effect of impurities on the bend ductility of cast molybdenum. High purity molybdenum was repared by re-melting under high vacuum. The ductility of "transverse-grain" specimens indicated that intergranular brittleness decreased with an increase in purity of the metal. THE production of as-cast molybdenum with high ductility at room temperature would make working of the metal easier and increase the usefulness of the as-cast metal. Furthermore, a .knowledge of the factors that influence the ductility of as-cast molybdenum might be applied to the problem of making fusion weldments having satisfactory room-temperature ductility. Individual grains of commercial as-cast molybdenum are slightly ductile at room temperature. However, the presence of carbides at the grain boundaries may cause the metal to fracture in a brittle manner. This behavior has been discussed.' The amount and distribution of the impurities in as-cast molybdenum would be expected, from previous research on the metal, to have considerable influence on its ductility. Some effects of oxygen and carbon on the mechanical behavior of the metal were discussed by Parke and Ham,2 Woodside,3 and Zappfe. Landgraf, and Worden.4 Parke and Ham2 found that, if a sufficient number of molybdenum oxide particles were present at the grain boundaries, the intergranular cohesion was reduced to the extent that arc-melted molybdenum would rupture intergranularly during hot forging. They also found that if the oxygen content was less than 0.003 pct, the cast molybdenum was hot forgeable. It is suspected, however, that forgeable molybdenum may contain a small amount of oxide that could reduce the ductility of the as-cast metal at room temperature. Also, there is the possibility of the unfavorable distribution of other impurities having a detrimental effect on the ductility of cast molybdenum. The results of a study of the influence of purity on the room-temperature ductility of cast molybdenum are presented here. Vacuum Arc-Melting to Produce High Purity Mo One way of determining the effect of impurities on the ductility of molybdenum is to prepare and test metal as free of all impurities as possible. Accordingly, the present investigation was undertaken with this in view. Arc melting in high vacuum (less than 0.1 micron of mercury) was chosen as the method for reducing the impurities below the concentrations occurring in commercial molybdenum. Commercial arc melting of molybdenum is carried out at about 50 microns pressure. During the arc melting, carbon and oxygen in the metal react to form carbon monoxide. By virtue of the vacuum process, the partial pressure of carbon monoxide is maintained at such a low value that the reaction greatly lowers oxygen and carbon contents. An excess of at least 0.03 pct C is used in commercial arc melting to insure that the oxygen content will be below 0.003 pct. The excess carbon remaining after the deoxidation step forms carbides on freezing. Some of the carbides precipitate at the grain boundaries and, as will be shown, have an unfavorable effect on the room-temperature ductility. In the present work, only the small amount of carbon (0.003 pct) contained in the commercial powder-metallurgy molybdenum used for melting stock was present. Partial removal of oxygen from the melt probably occurred as the result of the volatilization of molybdenum oxides, or by distillation of oxygen at the high melting tem-

Jan 1, 1953

By W. Rostoker, D. W. Levinson, A. Yamamoto

The influence of carbon on tensile strength, tensile ductility, transformation kinetics, and grain growth characteristics of selected Ti-Mo base alloys was studied. No systematic influence of carbon in tensile strength or significant deleterious effect on tensile ductility was observed. There was a marked increase in transformation rate due to carbon. Dispersed carbides exert a marked inhibiting effect on grain boundary migration, and thus effectively prevent grain coarsening during solution treatment in the ß phase field. AS part of a research program directed toward the illumination of factors governing modes of transformation, transformation kinetics, and mechanical properties obtainable through these transformations by heat treatment, Ti-Mo base alloys were selected for study. The binary system is a characteristic phase diagram type which has been studied in some detail', ' in relation to transformation kinetics and mechanical properties. Although carbon bearing alloys have acquired a bad reputation, the possibilities of melting titanium under conditions which occasion some carbon pickup are very attractive. It is therefore of considerable importance to know whether carbon, present as a dispersed carbide phase, is actually deleterious when all other detrimental factors are minimized. Basic alloy compositions containing nominally 3, 5, 7, and 11 pet Mo were prepared with systematic carbon addition up to 1 pet by weight. Various of these alloys were subjected to a series of critical and definitive experiments to delineate the effect of carbon on the transformation behavior and associated mechanical properties. Experimental Procedure Alloys were prepared from 115 Bhn magnesium-reduced sponge titanium. This sponge analyzed ap- proximately 0.05 pet C. Ti-Mo and Ti-C master alloys were made by arc-melting the sponge with high purity (99.9 + pet) molybdenum and spectro-scopic grade graphite, respectively. Alloys were then prepared from the master alloys and sponge by double are-melting. One kg ingots were prepared by melting in a nonconsumable electrode furnace. These ingots were forged at 1000°C to '/z in. rods, and cleaned and processed into electrodes for the second melting operation. The final ingots were ground to remove surface defects, then forged again to 1/2 in. or 3/8 in. diam rods for processing to test samples. It is significant that all of the alloys at all carbon levels forged satisfactorily. For convenience, the alloys will be referred to throughout the text by their nominal analyses. Samples for the study of transformation rates were prepared from 1/2 in. diam round stock. They were then solution treated in a helium filled tube furnace at 1000°C for 30 min prior to the isothermal transformation treatments in lead bath furnaces. Temperature control in both cases was within ±3oC. Following the isothermal transformation treatments the samples were water quenched. These experiments were carried out before the general adoption of the resistometric procedure for kinetic studies. The data were therefore obtained entirely by metal-lographic analysis. M, temperature was also determined by the metallographic method. Shoulder-type tensile test pieces were machined from heat treated, 1/2 in. diam slugs to provide a 0.252 in. test diam and a 1 in. gage length. The isothermal-type heat treatments were chosen from previous data' to provide three levels of strength and ductility.

Jan 1, 1957

By Guy N. Bjorge, A. J. M. Ross, S. J. Staple, J. D. Johnson, J. F. Wiggert

In recent years the Homestake mine has been served by three shafts, the B. &. M., the B. & M. No. 2 and the Ellison, supplemented by an inside shaft, the Milliken, extending from the 2000-ft. level to the 3200-ft. level. In 1932, when a new operating shaft was under consideration, the bottom of the mine was at the 3200-ft. level. The B. & M. and the B. & M. No. 2 shafts were down to the 1550-ft. level and the Ellison was being deepened from the 2600 to the 3200-ft. level. All ore was hoisted at the B. & M. and Ellison shafts. Levels below the 2600 level, which were under development only, were served by the Milliken shaft. Below the 1550-ft. level, the mine was served only by the Ellison shaft from the surface. Within a few years, when ore reserves above the 1550-ft. level would be depleted, operation would be limited to the Ellison shaft and the auxiliary underground shaft. The Ellison shaft alone was not adequate for hoisting the entire output from the deeper levels and also handling all men and supplies. Furthermore, assurance of safety and uninterrupted operation required two fully equipped shafts to the deeper levels. Therefore a new operating shaft was authorized in November, 1932, and was named for A. J. M. Ross, the mine superintendent. Plans for New Shaft The B. & M. shaft, begun in 1878 before much was known of the form and extent of the orebodies, was too near the ore and was endangered by ground movement. In 1924 this shaft was seriously threatened and sinking of the B. & M. No. 2 shaft, to supplant it, was begun. The latter was completed to the 1550-ft. level in 1928. In the meantime ground movement at the B. & M. shaft had practically stopped and, though loss of the shaft constantly threatened, ore hoisting was con-

Jan 1, 1937

By Sydney H. Ball

MINERALS used primarily for personal adornment and decorative purposes are called precious stones. To be so prized, the stones must possess beauty of color, must not be too common, and must be hard enough to withstand ordinary wear. If transparent, they must have brilliancy and fire. Almost one hundred minerals have been used as precious stones, the noble gems being the diamond, emerald, ruby, and sapphire; pearls are frequently included by courtesy. These gem stones, however, are sometimes equaled in beauty by fine opals, aquamarines, ourmalines, spinels, chrysoberyls (both cat's-eye and alexandrite), and spodumenes (hiddenite and kunzite). The Greeks, Romans, and medieval Europeans grouped together gem stones according to color and degree of transparency, and only as the niceties of mineralogy began to be known, about a century ago, was it realized how many different minerals have the beauty required of gem stones. Pliny, for example, did not distinguish between rubies and the red varieties of spinel and garnet, although he conjectured that the beryl and emerald were one mineral. GENERAL SURVEY Early man treasured bright colored berries, attractive shells, white teeth of wild animals and brightly colored pebbles, and used them as personal ornaments. In the eastern hemisphere, the earliest stones used were members of the quartz family (100,000 to 75,000 B.C.); then obsidian and amber (50,000 to 25,000 B.C.); the jade minerals, fluorspar and jet (22,000 to 7000 B.C.); turquoise (7000 to 3400 B.C.); lapis lazuli and garnet (prior to 3500 B.C.) ; emerald (2000 to 1800 B.C.) ; sapphire, ruby and diamond (800 to 500 B.C.). Indeed, gem mining is the oldest form of mining, and before any metals were known primitive man recognized about 18 gems and decorative stones. At first he sought them in stream gravels and residual deposits but by 3400 B.C. the turquoise mines of the Sinai Peninsula were operated. This was the world's first important hard-rock mining enterprise. The Afghanistan lapis lazuli mines may

Jan 1, 1949

By N. J. Themelis, P. Spira

The efficiency of the reverberatory furnace operation in producing. slags of 1020 copper content depends on the mixing and flow conditions in the bath. Radioactize-tmcer tests have indicated the jkaction of bath volume engaged inflow and the mixing conditions in the bath. The factors controlling the flow pattern of slag have been classified as laminar transfer flow, natrsral convection, and flou, due to the rapid addition or removal of slag.. Similarity criteria for model studies have been developed. The pyrometallurgical processing of copper begins with the smelting of either flotation concentrates, or direct-smelting ores which have been partially roasted to calcines. These materials are generally smelted in a reverberatory furnace, Fig. 1, and separate into two liquid phases, a sulfide matte and an iron silicate slag. he matte is tapped and subsequently reduced to metallic copper in a converter, while the reverberatory slag is usually discarded without any further treatment. Molten slag from the converting operation is returned intermittently to the reverberatory in order to recover its high copper content (1 to 3 pct Cu). The reverberatory furnace is about 115 ft long by 30 ft wide. In general, the solid charge is fed at intervals through openings along the sides of the roof and forms sloping banks from which the molten materials trickle down into the bath; the charge banks extend over a length of about 70 ft from the firing wall. The depth of the slag and matte layers varies from smelter to smelter; in the Noranda furnaces, the slag depth is 24 to 30 in., while the depth of matte at the taphole is about 20 in. Apart from smelting, the functions of the reverberatory are to recover most of the copper content in the converter slag by physical and chemical interaction with the furnace bath, and to provide adequate time for optimum separation between matte and slag. The efficiency of these operations depends on the mixing and flow conditions in the bath and is reflected on the copper losses in the slag. In the present study, the reverberatory furnace is considered as an open-channel chemical reactor and the driving forces for material transport through the bath are examined by means of flow and mathematical models. FLOW CONDITIONS IN THE REVERBERATORY FURNACE To facilitate the study of mixing conditions in continuous-flow reactors, two idealized patterns of flow have been accepted by workers in this field.' The term "backmix" flow is used to describe complete and instantaneous mixing in the reactor (perfect mixing); all particles have the same chance of leaving the system, independently of their time of entrance, and the fluid is uniform in composition throughout the vessel. On the other hand, "plug" flow, or "piston" flow, assumes that a fluid element moves through the reactor without overtaking or mixing with fluid entering at an earlier or later time. In addition to the two idealized patterns of flow, "deadwater" flow accounts for that portion of the fluid which is moving so slowly that it may be assumed to be stagnant. According to the definition by evensppiel,' the cut-off point between active and stagnant fluid may be taken as material which stays in the vessel for a period twice the mean residence time. The flow patterns in real vessels may be approximated by a combination of the above flows. Thus, the vessel is assumed to consist of interconnected flow regions with various modes of flow existing between them. The flow pattern may be determined directly from the flow paths of fluid through the essel. -However, the difficulty of obtaining and interpreting such information has led to the alternate approach of determining the residence time distribution of fluid elements by means of stimulus-response studies. The stimulus is provided by introducing a tracer in the inlet stream and the response by the record of the change in tracer concentration in the exit stream from the reactor. Such tests have been conducted in glass tank furnaces using either chemical7"9 or radioactive tracers1'-'' and, in one case, experiments have been reported for a metallurgical furnace.'"

Jan 1, 1967

By Arnulf Muan, Klaus Schwerdtfeger

Equilibrium ratios C02/C0 of a gas phase coexisting with selected phase assemblages of the system Fe-Mn-0 have been determined in the temperature range 1000" to 1300°C. The oxygen pressure for the "hfnO" +hfn30, equilibrium and for the "(Fe,hTn)O" + (Fe,Mnh 0* equilibrium at high manganese contents has been determined by electromotive force measurements using stabilized zirconia as a solid electrolyte. The notstoichometry 01' "hTnO" and of "(Fe, iM1z)O" solid solutions has been determined by ther-mog-/avi?netry and by wet-chemical analysis. The data obtained are used to derive activity-composition relations in "(Fe,hfn)O" and (Fe,Mn),O4 solid solutions. WUSTITE "FeO" and manganosite "MnO" form a continuous series of solid solution at high temperatures,' and so do magnetite Fe304 and the high-temperature, cubic modification of Mn304 (Ref. 2) (high hausmannite, -1170). The oxides "FeO" and "MnO" are cation-deficient phases.495 The nonstoi-chiometry of "(Fe,Mn)O" solid solutions has been studied by Engell and ~ohl' at two selected C02/C0 ratios at 1250°C. The two oxide end members of the spinel solid solution, FesO4 and Mn,04, however, are known to be close to stoichiometric under the experimental conditions used in the present investigation.''' The oxygen pressures of "(Fe,Mn)07' solid solutions in equilibrium with iron have been determined by Schenck and coworkers,8 by Foster and welch," and by ~n~e1l.l' The two former groups equilibrated the condensed phases in C02-CO atmospheres of lmown compositions, whereas Engell" used a galvanic cell with stabilized zirconia as a solid electrolyte. The results of these investigators are not in good agreement. Activities of FeO in manganowiistite as calculated from the results of Foster and Welch show ideal behavior, those of Engell yield a pronounced positive deviation, and those of Schenck et 01. show a moderate positive deviation from ideality. In the present work oxygen pressures for the iron + manganowiistite and manganowustite + spinel equilibria and the nonstoichiometry of manganowiistites have been measured. The data were used to calculate activities in the manganowiistite and spinel solid solutions. EXPERIMENTAL METHODS The COz/CO ratios at which manganowustite and iron are in equilibrium were determined by thermo-gravimetric and quenching methods. Experimental details are described in a previous publication.'2 In the thermogravimetric technique, incipient reduction of manganowiistite pellets to metallic iron was observed as a break in the weight vs log COZ/CO curve. In the quenching technique, manganowiistite samples were partially reduced to metallic iron, or the metallic iron of manganowustite + metallic iron mixtures was partially oxidized to manganowustite, in atmospheres of constant C02/CO ratios. After quenching the composition of the oxide phase was determined by X-ray lattice parameter measurements and comparison with a standard curve obtained from oxide solid solutions of known compositions. The nonstoichiometry of "MnO" and "(Fe,Mn)07' solid solutions was determined by chemical analysis of samples equilibrated in C02-CO atmospheres and quenched to room temperature, as well as thermo-gravimetrically by reducing (Fe,Mn),04 or Mn304 to manganowiistite or manganosite. The equilibrium between manganowiistite and (Fe,Mn),04 was measured thermogravimetrically by reducing (Fe,Mn),04 solid solutions having composition in the range of %„ l(NFe +NM) from 0 to 0.63. No experiments could be performed with this technique at higher manganese contents, because the equilibrium C02/C0 ratios are too large for accurate control. An additional difficulty arises at the higher manganese contents due to the strong increase in oxygen content of the manganowustite phase with increasing log Py near the manganowiistite-spinel boundary. Consequently a sharp break in the weight loss vs log C02/CO curve cannot be observed at the phase boundary. At high manganese contents of the manganowiistite, e.g., (NMn/(NF~ + NMn) > 0.9, electromotive force measurements with stabilized zirconia as a solid electrolyte were made to determine the equilibrium oxygen partial pressure. Experimental details are described in a previous paper.* Mixtures of "(Fe,Mn)O" and (Fe,Mn),04 were pressed to pellets, and the oxygen pressure of the equilibrated samples was compared to that of Ni + NiO mixtures in the cell The composition of the manganowiistite in the equilibrated two-phase mixture was determined by lattice parameter measurements and comparison with known standards. The oxygen pressure for the Ni + NiO equilibrium was taken from available data.l3~l4 No reliable results were obtained with the electromotive force technique on iron-rich oxides. The electromotive force drifted strongly with time in this composition range. An additional difficulty arises from the partial de-

Jan 1, 1968

By Charles S. Barrett

There is a road into the microscopic realm that has remained untraveled through all these years of intense activity with high-power optical and electron microscopy. The road is worthy of careful scouting by metallurgists and other investigators, for it leads into relatively new country and it makes some areas accessible that heretofore could be reached only by very indirect paths or by the use of imagination. And when the road passes through familiar territory it frequently permits a new view of commonplace things that should prove of value from time to time. An accepted way to interest people in new sights such as this is to present an illustrated travelogue. This I propose to do, using many pictures taken in my recent exploration of this road. In the manner of travelogues, I shall touch briefly upon a large number of different subjects in physical metallurgy and shall attempt to give an exhaustive treatment of none, for the objective is to provide a means for further research, to interest others in it, and to indicate what appears at the moment to be profitable directions for it to take. The method I shall present involves X-rays, but does not make use of the usual accompaniments of X-ray research such as reciprocal lattices, Fourier series, or the stereographic projection. The method is so simple in its fundamentals that it could have been developed 2o years ago, or perhaps even 30 years ago. It is well to have a destination for our travels, so that when we are through we shall have explored some region of importance, despite our preoccupation with the novel means of transportation and our interest in the sights to be seen along the way. So let us name the Cold-worked State as our destination, and make side trips into the territories known as Recovery, Recrystallization, and Precipitation-hardening. A great many investigations have been made of the nature of cold-worked metal, and a great variety of methods used, many of which are indirect, such as X-ray line intensities, X-ray line widths, calori-metric measurements, and magnetic measurements. Since comprehensive reviews of these investigations have been published in recent years, they need not be discussed here. The investigations that were the direct forerunners of the present work should be first mentioned. In 1931 I became interested in the structure of individual spots in X-ray diffraction patterns.l When a crystal is placed in the narrow pencil of X-rays in a Laue camera, the spots recorded on the film are not always uniformly black, but may have an internal structure. The meaning of this may be understood from Fig. I, which represents a narrow beam containing X-rays of many wave lengths (''general radiation") penetrating a crystal in the direction of the arrow and forming a pattern on the vertical film at the right.

Jan 1, 1945

By J. L. Giove, J. M. Hodge, R. G. Storm

The hardenability effect of molybdenum has been evaluated by a number of investigators, including one of the present authors.1,2,3,4,6 Considerable discreMncy exists, however, among the results of these various investigators, and two of them, Brophy3 and Kramer,4 have indicated that the apparent hardenability effect of molybdenun would vary, depending upon the other alloying elements in the steels being considered. The results of previous, unpublished work conducted at the Duquesne Works Laboratory of the Carnegie-Illinois Steel Corporation also have indicated significant differences in the hardenability effect of molybdenu~n in nickel and in chromium steels. The present investigation was undertaken in an effort to establish the mechanism governing this difference in the hardenability effect of molybdenum. This work involved both end-quench hardenability and isothermal transformation tests on two series of steels of varying molybdenum content. One steel contained 3 pct nickel and the other 1 pct chromium. It was hoped that such studies would shed further light on the mechanism of this behavior. Materials and Experimental Work MATERIALS The chemical compositions of the steels used in this investigation arc shown in Table 1. These steels were furnished by Battelle Memorial Institutc in the form of 100-lb induction furnace ingots. The top half of each ingot was forged to 1 3/8-in. square billets and then rolled to I-in. round bar stock for isothermal transforma- tion studies. The bottom half of each ingot was forged into approximately 1 1/4-in. rounds for end quench tests. All of the steels were normalized from 1650°F and tempered at 1100°F before nlachming to end quench or isothermal samples. END-QUENCH TESTS standard l-in. diam end-quench tests were made on each of the steels. The test bars were austenitized at 1600°F for 30 min,, quenched in a standard Jominy jig, and hardness surveys were made in all tests. The 95 pct martensite point was deterInined from hardness values5 and cheeked by metallographic examination. The jominy distance values for 95 pct martensite were converted to hardellability values in terms of ideal diameter (Dl), using a revised carve for the relationship between Jominy distance and ideal diameter. This curve was based on the cooling time from the A1 to the bainite nose temperatures rather than on the usual criterion of half-temperature time. The cooling rates as determined by Russell and Williamson9 were used as a basis for this relationship. The derivation of this curve is described in detail in the appendix. ISOTHERMAL TRANSFORMATION STUDIES Samples for the isothermal transformation studies were quarter sectors of 1/16.is-in. thick slices from the 1-in. round bars. All samples were austenitized for a total the of 15 min., transferred rapidly to a lead bath for isothermal transformation, and brine quenched from the lead bath. A time of 3 see was allowed for the sample to come to the temperature of the lead bath, and this time was not included in the isothermal transformation times. Each sample was examined metallo-graphically at a magnification of 100 diam. The per cent transformation was estimated by comparison with standard micrographs, and the values were plotted against the on log/log coordinate paper. At least 4 and as Inany as 10. points were plotted for each steel. A line was drawn through the points for each steel, and the times for 5 pct transformation were obtained from the plot for each steel. Isothermal transformation diagrams in terms of 5 pet total transformation, covering the temperature range of 800 to 1200°F, were determined in this manner for an austenitizing temperature of 1600°F. The times for 5 pct transformation at the bainite nose for austenitizing temperatures of 1800 and 2000°F were also determined in the same manner. These times for 5 pct total transfor-

Jan 1, 1950

By H. B. Pulsifier

THE following report on the structure of copper is the result of work done in the laboratory of the Rome Wire Co. early in 1925. Previous work had indicated to the author that excellent results might be expected if a suitable technique in surfacing and etching could be developed. The resources of the Rome Wire Co. enabled this metal to be studied more intensively than previously, although none of the materials were investigated exhaustively. The material presented is hardly more than a preliminary summary of the most obvious character of the metal; a much longer research would have been necessary to solve many of the pressing problems connected with the casting and working of copper. The Rome Wire Co. has generously released the paper; to Dr. E. H. Darby, technical supervisor of the company, are due particular thanks for his appreciation of the importance of metallographic study of copper and for his effective support in the prosecution of the work and in making its publication possible.

Jan 1, 1926