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By Georges Caraghiaur

INTRODUCTION A small, independent mining enterprise (SIME) is an independently owned and operated business concern engaged primarily in mineral development, from the exploration to the production stage. By definition, a SIME is not dominant in its field and has no long-term financial backing. It is not a major producer of minerals, nor is it a petroleum company, a government organization or a subsidiary of such organizations. A SIME may or may not be listed on stock exchanges. The SIME is also called small miner, junior mining company, speculative mining company, and penny-stock mining company. The survival and growth of a SIME is most often controlled by an independently minded entrepreneur, who not only conceives and carries out new projects, but is materially affected by the success or failure of these projects. Usually, a SIME does not have a large or constant cash flow. Such a lack of long-term financial backing forces the SIME to meet the challenge of finding capital for its activities on a step-by-step basis. Its survival strategy is thus based on finding funds at the right time, of the right type and in the right quantities. The purpose of this paper is to show that the type of venture in which a SIME is involved affects the difficulty of raising new capital and the choice of possible sources of funds. The Small, Independent Mining Enterprise (SIME) The SIME is not a figment of the imagination of financial speculators. In Canada, there are more than 1,800 small mineral enterprises which spend on the average less than $1,000,000 per year on activity which is directed at bringing forth new mineral supply. In the United States, 64% of the non-fuel mining operations are conducted by nine or fewer men, and the coal industry is characterized by several thousand smaller independent producers, still predominantly family owned or controlled. In Chile, 80% of the mines can be classified as small mines. In the Philippines, approximately 60% of metal mining operations are classified as small mines. The SIME is actively engaged in mining all over the world, and very much so in the Pacific Rim. The Mineral Supply Process The whole process of bringing forth new mineral supply involves a dynamic sequence of activities, ranging from the initial exploration for a mineral occurrence to the production of a marketable product. A typical sequence is outlined in Figure 1. At the grass-roots exploration stage, a series of geological, geophysical and geochemical tests is aimed at locating a mineral occurrence. Especially in the early phases of such activities, the uncertainty (risk) surrounding a venture is high, since only general geological information exists on which to base a judgement of the economic viability of the venture. Such risk is attractive to few investors. As the information-gathering process continues, uncertainty diminishes. Once exploration efforts result in the discovery of a mineral occurrence, i.e. when indications of mineralization and mineable widths are obtained by drilling, there is still uncertainty concerning the extent of mineralization and the probability of having located an economic mineral deposit. The expected return on investment at such a stage may well be negative but the slight possibility of a very high positive return will make a number of financial sources available to an exploration company. At the development stage, much of the uncertainty

Jan 1, 1985

By B. L. Averbach, Morris Cohen, S. A. Kulin

The martensitic transformation can be initiated by elastic stresses at temperatures above M. in a steel containing 20 pct Ni and 0.5 pct C. Shear strains and normal tensile strains acting on a potential habit plane promote the transformation but compressive strains oppose it. THE strain sensitivity of the martensitic transformation has long been recognized. It is now well known that martensite formation can be induced by plastic deformation at temperatures below, and not too far above, the M, point.' However, the exact role of elastic vs. plastic strains and of the concomitant stresses has proved to be a very elusive matter. Many investigators2-' of the steel hardening reaction have made use of the stresses resulting from volume changes to account for such observations as the existence of retained austenite and its variation across the section of a bar, the change in the amount of retained austenite with quenching rate, and the self-stopping nature of the transformation when the cooling is stopped. The effect of applied strain as an independent variable has been studied in 70 pct Fe-30 pct Ni alloys by Scheil7 and McReynolds.8 Some data are also available for lithium and Li-Mg alloys,9 Cu-Zn,10 Cu-Sn and Cu-A1 alloys," and aus-tenitic stainless steels."-" It has been found that martensite formation can be induced isothermally, even at temperatures above M,, by mechanical deformation of the parent phase. The competitive nature of plastic yielding by slip and by the martensitic reaction has been depicted by Scheil.7 Basically, Scheil postulated that: 1—at temperatures not too far above M, (where austenite is less stable than martensite), a critical resolved shear stress (within the elastic range) is required to promote the transformation to martensite; 2—at and below M,, the austenite lattice becomes mechanically, as well as thermodynamically, unstable and shears over spontaneously into martensite without the application of external stress; and 3—at temperatures sufficiently far above M8, the critical resolved shear stress for martensite formation increases to a level above that required for slip, and plastic flow then supersedes the transformation when external stress is applied. Scheil's concepts were tested by McReyno1ds8 ho found no change in the elastic moduli (measured both statically and dynamically) of 71 pct Fe-29 pct Ni alloys in the vicinity of the M, temperature. Since the moduli did not approach zero or become negative on cooling to M,, it was concluded that the austenite lattice does not become mechanically unstable at M2, as postulated by Scheil. McReynolds also reported that M, is not raised by elastic stresses. Accordingly, plastic deformation was considered to stimulate the transformation by generating martensite nuclei in the distorted regions of the parent phase. The above issues with regard to the role of applied stress require clarification, if a basic understanding of the martensitic transformation is to be obtained. For example, in the reaction-path theory,'"," it is postulated that strain embryos exist in the austenite that provide part of the activation energy for the nucleation process. These embryos are visualized to be regions of localized strain in which the atoms in the austenite lattice are displaced part way along the path to their ultimate positions in the martensite. Consequently, it would

Jan 1, 1953

By M. A. Selim, W. H. Somerton

Thermal expansions and heats of reaction of three typical sandstones were measured in the temperature range of 25°to 1,000°C. The significance of these data in subsurface heat-transfer calculations is discussed. Linear thermal expansions were measured both parallel and perpendicular to the bedding planes. Volume expansions are reported as the perpendicular expansion plus two times the parallel expansion. Expansion behavior of the sandstones was found to be controlled by the expansion characteristics of the quartz content. Differential expansion of the quartz grains and other minerals included in the sandstones caused permanent deformation of the heated samples after they were cooled to room temperature. Structural damage resulting from heating is probably an important cause of the reduction of thermal conductivity of heated samples. Measurements of heats of reaction were based on the known heat required for a- quartz inversion. Thermal reactions, which probably include deby-droxylation of clay minerals and decomposition of carbonate minerals contained within the samples, were found to require more than one-fourth of the amount of heat necessary to raise the temperature of the rock alone. In shales and limestones, the reaction heat could be substantially greater than that required from specific heat considerations alone. INTRODUCTION In earlier work, l-3 methods of measuring thermal properties were developed and thermal data for several sedimentary-rock types were reported. Data included thermal conductivity, specific heat and thermal diffusivity. In addition, calculations of heat transfer in subsurface formations may require data on the thermal-expansion characteristics of rock and the heats of reaction of mineral constituents. Thermal expansion of rocks is relatively small in magnitucle and, from the standpoint of change in bulk density, has only minor effects on heat-transfer cliaracteristics. Thermal-expansion behavior, however, may have significant effects on the structure of rocks. Differential expansion of different minerals and along different crystal-lographic axes may result in structural damage which could effectively reduce the thermal conductivity of the rock. Many mineral constituents of sedimentary rocks undergo phase or related changes when heated to sufficiently high temperatures. Although some of these reactions (such as the a-ß quartz inversion) are reversible and the heat absorbed is returned to the system upon cooling, many of the major reactions are irreversible. Through certain temperature ranges, the additional heat energy required to complete the reactions may be nearly as great as that necessary to raise the temperature of the rock in the absence of thermal reactions. If the heat requirements for these reactions are not considered, serious errors in heat-transfer calculations may result. Thermal-tzxpansion and thermal-reaction data have been obtained for three typical sandstones. Methods of measurement and results obtained are reported and discussed in the following. THERMAL EXPANSION OF SANDSTONES The linear expansions of three outcrop sandstones (Bandera, Berea and Boise) have been measured in the temptbratue range of 25° to 1,000° C. Expansion measurements were made in the directions parallel and perpendicular to the bedding. The differential expansion apparatus used is that described by Mitoff and Pask.4 The test sample is heated in an electric furnace with a temperature rise of 6°C/minute. The lengthening of the samples upon heating is compared with the small and known expansion of a fused silica rod. The change in length is transmitted to an X-Y recorder by means of a Statham transducer. A maximum error of ± 1.5 per cent has been obtained with this apparatus

By F. E. Jaumot, A. Sawatzky

IT as long been recognized that there is a need for accurate systematic data on diffusion in solids. Originally, such data were needed to check existing theories but, more recently, it would appear that it could be used most advantageously as a guide to, or a check for, much needed extensions of the theory of diffusion. The awareness of the conditions which are important to experimental accuracy, the availability of the materials for accurate experiments, and the techniques have improved to the extent that it would now seem to an experimentalist that, unless extensions of the theory are made which take into account the fundamental parameters of the atoms, the electrons, and the lattice in some detail, the field of diffusion will rapidly become an empirical or semi-empirical field. The present series of experiments was designed to provide accurate data on the diffusion of the elements of the IB and IIB subgroups in silver; that is, to provide data on the diffusion in silver of three face-centered-cubic elements with roughly similar chemical properties, but with different atomic or ionic sizes and, similarly, for three noncubic elements. The elements of these two subgroups have different valences, so that the data will not give any significant information on differences due to the crystal structure of the solute. The present paper reports data on the diffusion of copper and mercury in single crystals of silver; the data for the other elements of the IB and IIB subgroups were reported previously by the authors1'2 and by Tomizuka and Slifkin.8 Experiment The general technique used was identical to that previously described1,2 and will not be repeated here. In all cases, the sectioning technique and high specific activity isotopes" were used. The short half-life of Cu64 made decay corrections more important than for the other isotopes, and necessitated around the clock shifts while data were being taken. Each section was counted at least twice (as was true for all longer half-life isotopes) and a monitor was counted along with each sample. Data for the diffusion of mercury in silver are presented at a greater number of temperatures than for the other solutes. This is a result of two circumstances. First, six (of 30) samples had to be discarded because of pitting or recrystallization which occurred during the diffusion runs, even though the samples had sustained high temperature prediffusion anneals. Either of these was a very rare phenomenon in the other experiments, and their occurrence in this case is considered in more detail below. Second, the curves of the logarithm of the activity of the sections vs the square of the penetration deptht were, in general, quite good, but frequently seemed to show one point to have high activity and the next point to have slightly low activity in terms of the best straight line. When this occurred, there was remarkable regularity of the high-low sequence. In any event, the results, as far as diffusion coefficients are concerned, were not affected by this amalgam effect. In fact, the mercury data had the highest internal consistency of any of the data. Results Diffusion of Copper in Silver—-Diffusion runs were made at eight temperatures In the temperature range from 700° to 950°C, for times ranging from 5 to 45 hr. A linear curve of the logarithm or the activity vs the square of the penetration depth was obtained for all samples. Table I summarizes the results for individual samples and Fig. 1 gives a plot 02 the logarithm of the diffusion coefficients as

Jan 1, 1958

By M. A. Dayananda

Based on the Kirkendall frame of reference, a method is proposed for the determination of atomic mobilities of all the diffusing species in a multicorn-ponent system with a single diffusion couple. The method is based on an atomic mobility model developed on the concept of negligible interactions among the intrinsic fluxes. It is shown in the model that mobilities can be obtained directly from the cumulative intrinsic fluxes past the Kirkendall interface. The proposed method replaces the need for a prior determination of interdiffusion coefficients far the calculation of mobilities. Relations between intrinsic diffusion coefficients and mobilities are derived and the mobility calculations are illustrated with diffusion data in Cu-Zn-Mn alloys at 850°C. ThE concept of "intrinsic flux" with respect to a fixed lattice was introduced "i Darken1 to explain toa Kirkendall effect2 demonstrated by the motion of inert markers during isothermal diffusion in single-phase binary solid solutions. Based on this concept, intrinsic diffusion studies have been made in various binary metallic systems3,4 employing such a lattice frame of reference, commonly referred to as the Kirkendall interface. Similar approaches, both theoretical and experimental, have been presented5"10 to study intrinsic diffusion in multicomponent systems. Based on the direct integration of Fick's law extended to multicomponent diffusion, Philibert and Guy8 proposed a method for the determination of intrinsic diffusion coefficients. For an n-component system, this procedure requires an experimental study with (n — 1) diffusion couples, all having their Kirkendall interfaces at the same compositio;, where n(n — 1) intrinsic diffusion coefficients are defined. This technique has been employed for ternary diffusion studies by Dayananda and Grace" and Guy and Leroy.11 A different approach is recommended by Ziebold and Cooper,12 who have derived relations between interdiffusion coefficients and atomic mobilities employing fluxes referred to the local center of volume. Their analysis is based on the simplifying assumption of negligible interactions among intrinsic fluxes. This assumption has been considered satisfactory for dilute solutions.5"7 The use of this analysis for the calculation of mobilities requires an initial determination of interdiffusion coefficients with a set of diffusion couples having intersecting diffusion paths. It is the purpose of this paper to propose a method that would permit a direct determination of mobilities of all components of a multicomponent system from a single diffusion couple. This method is based on a mo- bility model developed with diffusion fluxes referred directly to the Kirkendall interface, generally identified by inert markers. gen erall, like that of Ziebold and Cooper,12 employs the simplifying assumption that the flux of each component relative to a fixed lattice is caused only by the driving force of its own chemical potential gradient. THE KIRKENDALL INTERFACE Inert markers are employed in diffusion couples to locate experimentally the position of the Kirkendall interface. They are initially placed at the weld interface for "sandwich" couples, or at the original vapor-solid interface for vapor-solid couples. Studies of marker motion in binary systems3'4 with both types of couples indicate that markers remain in a plane of constant composition and move with this plane para-bolically with time. Parabolic marker movements were also observed in ternary Cu-Zn-Mn couples by Dayananda and Grace.10 It is reasonable to expect a similar marker behavior even for diffusion couples with a higher number of components.

Jan 1, 1969

By W. A. Tiller, D. H. Lane

A simple zone melting technique for investigating the effect of ultrasonic irradiation upon ingot solidification is described. The effect of i) ultrasonic power level, ii) freezing velocity, iii) constant or variable frequency, iv) direction of irradiation, and v) transducer-cozlpling bar joint upon the grain size of type 316 stainless steel have been investigated. The results of this study support the postulate that the ultrasonic vibrations increase the nucleation probability in the layer of liquid adjacent to the freezing interface. In the first paper of this series,l the possible mechanisms whereby ingot structure may be altered by irradiating a solidifying melt with ultrasonic vibrations have been discussed. A new technique for efficiently introducing the ultrasonic energy into the solid-liquid interface region was presented and applied to ingot preparation by the consumable-electrode arc-melting technique. The experimental results support the postulate that the ultrasonic vibrations may refine the ingot structure by increasing the nucleation probability in the zone of liquid adjacent to the solid-liquid interface. The present paper describes the application of the same technique to a relatively simple laboratory-scale zone-melting apparatus. This apparatus is found to be well suited to the detailed study of ultrasonic technology in this area and allows one to determine, in particular, the minimum ultrasonic power level needed to produce a certain grain size in a particular material. The results of this study support the nucleation mechanism for grain refinement, but do not provide any deeper insight into the specific nucleation mechanism responsible for the effect. EXPERIMENT The apparatus used in these experiments is shown in Fig. 1 and illustrated schematically in Fig. 2. The material to be studied, type 316 stainless steel, was in the form of a 3/4-in. sq bar 30 in. long. This bar was placed in a square open-topped mold with open ends made from high-purity graphite coated with a flame-sprayed Al2O3, skin. Surrounding the crucible was a molybdenum susceptor with 3/8-in. diam holes spaced at 1-in. intervals along its length to serve as sight ports. A tapered transducer horn was brazed to one end of the specimen. The entire assemblage was enclosed in a quartz tube, the transducer itself projecting out one end and resting in a cooling tank. A vacuum seal between the coupling bar and the end plate enclosed one end. A similar plate and seal enclosed the other end. The system is gas tight and can be operated under vacuum or an inert atmosphere. For these experiments, flowing argon at 15 in. of Hg pressure was used. The heat source for melting the stainless steel specimen was a 2-in. long 3-kc induction coil placed around the quartz tube; this source heated the susceptor, inductively melting about a 3-in. zone of the sample by radiation. To move the molten zone at a specified rate, the induction coil was moved down the tube at this rate with the aid of a simple pulling device. Thus, the sample could be irradiated at varying ultrasonic frequencies and power levels and could be solidified at varying rates. The power input to the transducer was measured using a "John Fluke Model 120 VAW-Meter." 1 The power delivered to the interface region is probably only about 50 pct of that measured on the VAW-meter. In a typical run, when the ultrasonic power was turned on, the interface of the molten zone closest

Jan 1, 1961

It has been established that molybdenum sesquisulphide, not molybdenite, is in equilibrium with molybdenum metal and sulphur vapor in the vicinity of 1100°C. The S2 pressure for this system has been obtained using the Knudsen orifice method and the standard free energy for the dissociation of S2. THIS work was undertaken to help in determining the thermodynamic properties of the molybdenum sulphide which is in equilibrium with metallic molybdenum and sulphur vapor in the temperature range 1025" to 1150°C. From the results of MontoroL and of Parravano and Malquori' molybdenite would be expected to be in equilibrium with molybdenum metal, while the results of Guichard indicate that a lower sulphide must be in equilibrium with the metal. Thus it was concluded that the problem warranted reconsideration, especially in view of the suspiciously low temperature independent term for the standard free-energy function for the reaction MoS² Mo + S,. The reaction was calculated and duly noted as being low by Richardson and Jeffes,' using the data of Parravano and Malquori.' Experimental Method The general method used in this investigation is that of the Knudsen orifice method for the determination of equilibrium pressure. The apparatus and technique are similar to those described for the determination of the vapor pressure of silver.% owever, a closed-end McDanel tube instead of fused silica was used to maintain the vacuum, a molybdenum effusion cell with a replaceable lid was employed instead of a silica cell, and a titanium getter maintained at run temperature was used to assure that no oxidation of the molybdenum or molybdenum sulphide was taking place. All runs were made at a residual pressure less than 10-5 mm Hg. The data are given in Table I. Runs 1 through 13 were obtained using molybdenite, analyzed 98.5 pct, from the Molybdenum Corp. of America. The remaining runs were done with a sample from the Climax Molybdenum Corp. which was their grade No. 3 and analyzed 59.87 pct Mo. The weight loss of the cell during heating up and cooling down was subtracted from the total weight loss of the cell during the run. Also, when the tem- perature was changed, the Knudsen cell was placed in the vacuum chamber and heated at temperature for several hours in order to allow the sulphide and the metal to adjust their compositions to the equilibrium values, to desorb or adsorb gases into or from the molybdenum cell itself, and to desorb any water from the molybdenum sulphide or molybdenum powder inside the cell. Water may have been adsorbed inside the cell because, after each run, the top of the cell was removed and the material in the cell was stirred to insure that a layer of molybdenum metal would not build up and obstruct the passage of sulphur vapor into the gas phase. It was established that the molybdenum cell alone decreased in weight an inappreciable amount when heated at the highest run temperature for long periods of time. There are two questions to be answered before the data in Table I can be used to calculate thermodynamic functions: 1—Which molybdenum sulphide is in equilibrium with molybdenum metal and sulphur vapor? 2—What sulphur species are present in the vapor phase? It can be assumed safely that no molybdenum is vaporized, since its vapor pressure is almost negligible at these temperatures. It will be shown subsequently that no sulphide of molybdenum is volatile. Question 1 was answered in the following way: The especially purified molybdenite, obtained from the suppliers mentioned previously, was charged

Jan 1, 1956

By D. W. Frommer, M. M. Fine

Mineral dressing research showed that iron concentrates of commercial quality could be produced from the Pea Ridge deposit near Sullivan, Mo. Magnetic separation and flotation, on a laboratory scale, yielded concentrates ranging from 60.0 to 71.4 pet Fe at recoveries of 89.9 to 97.6 pct. Early in 1957 St. Joseph Lead Co. announced discovery of three new centers of iron ore deposition in east central Missouri.' The discovery resulted from exploratory drilling in the vicinity of a magnetic anomaly or high. A deep hole, drilled into the Pre-Cambrian porphyry to determine the cause of anomaly, penetrated a magnetite-rich deposit.' The magnetic surveys that revealed the anomalies were begun by the Missouri Geological Survey in 1929 and were continued into the 1930's.3 At that time an area in Crawford County known as the Bourbon magnetic high was located. A second anomaly, similar in size and intensity, was discovered about six miles to the northeast in Franklin County in the vicinity of Sullivan. This area was not studied in detail until the early 1940's. To determine the cause of the anomalies, the USBM drilled four holes at the Bourbon site in 1943-1944.4 The most productive hole penetrated four mineralized zones having a total thickness of 127.5 ft. These zones contained magnetite in rhyo-lite porphyry at depths between 1600 and 2000 ft. Additional iron ore below 2000 ft was considered a possibility at the time. Some years later, the USGS, Missouri Geological Survey, St. Joseph Lead Co., and others cooperated in sponsoring an aeromagnetic survey of the Bourbon-Sullivan area which resulted in discovery of a third high, about eight miles distant at Pea Ridge. This deposit, with an estimated reserve of 50 to 100 million tons of iron ore, is considered the main find, although other orebodies in the same general area are of definite interest.' When this discovery was announced, St. Joseph Lead also revealed plans to exploit the deposit jointly with Bethlehem Steel Co. A new corporation, Meramec Mining Co., was established, and 1962 was set as the target date for completing physical plant.2 Annual production goals of 2 million tons of beneficiated and pelletized iron ore were proposed. Preparation of the site for shaft sinking was begun in June 1957. Orebody and Character of Samples: Drilling to date has established the Pea Ridge orebody as a crescent-shaped pipe about 300 ft wide. Some drillholes were bottomed at 2800 ft in very good iron ore.6 he orebody is predominantly magnetite, although hematite and a mixture of hematite and magnetite occur in the upper areas and peripheral walls. Drillhole cores representing ore from different areas and depths of mineralization were grouped into composites for testing. These composites consisted of: 1) medium grade mixed hematite and magnetite, 2) high grade mixed hematite and magnetite, and 3) high grade magnetite. The medium grade ore came from three holes with depths of i350 to 1900 ft. The high grade mixed hematite and magnetite cores came from the 1790 to 2812-ft interval of one hole. Partial chemical analyses of the three samples, given in Table 1, reveal that all are excessively high in phosphorus and sulfur, and sample 1 is

Jan 1, 1960

By C. W. Carpenter, P. T. Bail, J. E. Bobek

This paper presents the results of model studies made to demonstrate the validity of applying the "basic" waterflooding scaling relationships of Rapoport1 to water-wet reservoirs composed of communicating strata of different permeability. Results demonstrate that these relationships can be validly applied, and also show the combined effect of variables on recovery. This demonstration was needed to confirm that the sizable effects of communicating strata on waterflood behavior, observed in model studies, were actually representative of field behavior. INTRODUCTION Rapoport1 Collins2 and others have presented scaling laws for modeling water-oil displacements. The validity of these laws has been experimentally demonstrated for homogeneous systems only. Recently, however, several investigators have presented the results of multilayer model studies made to determine the effects of viscous, capillary and gravitational forces on oil recovery in systems composed of communicating layers of different permeability. Dyes and Braun,3 using miscible displacements to simulate water flooding, showed that vertical communication adversely affects recovery at unfavorable viscosity ratios in the absence of capillarity. Ogandzhanyants and Egorova, 4 Gaucher and Lindley,5 and Richardson and Perkins6 modeled water-oil displacements in layered systems using immiscible fluids with capillary forces present. These investigators found more efficient behavior than in the miscible system of Dyes and Braun. However, since the scaling laws had not been verified for heterogeneous systems prior to or during these tests, it was necessary to assume that the results were representative of field behavior. This report presents the results of model studies made at Jersey Production Research Co. to find out if the waterflooding scaling relationships are valid when applied to water-oil displacements in heterogeneous reservoirs with vertical communication. Data obtained in the study show the combined effects of viscous, capillary and gravitational forces on oil-recovery behavior. The studies were performed in strongly water-wet systems where strong imbibition forces were present. For systems of different wettability, the effects of capillary imbibition would be somewhat different than those presented. APPROACH The scaling laws studied were those developed by Rapoport1 and designated by him as "basic" scaling laws. These relationships require that the model be scaled to the geometry of the prototype, and that the model and prototype be operated at the same viscosity ratio and have identical relative permeability curves, contact angles and boundary conditions. It is also necessary that the groups** be identical in the two systems, although any of the parameters making up the groups may be different. Finally, the capillary pressure of one system must be directly proportional to that of the second. Studies were conducted in two four-layer models, representing quadrants of five-spots, which were geometrically similar and which had the same glass-bead packing. The fluids used assured the same wettability in both models. Thus, the contact angles and relative permeabilities of comparative sand layers in the two models were identical and the capillary pressures were directly proportional. However, one model had a characteristic length three times that of the other. To make the scaling groups equal and to check the scaling laws, it was necessary to adjust the rate, water-viscosity level, interfacial tension and water-oil density difference to compensate for the difference in model sizes.

By R. Adair, W. R. Hudspeth, W. T. McDaniel

ANEW method for concentrating the flake mica either from present washing plant tailings or from new feed has been developed. In this paper, flake mica refers to that which occurs in weathered granites, alaskites, pegmatites, and schists in a form too fine to be considered sheet mica. It ranges in size from 1 in. or more down to 200-mesh or finer and occurs with kaolin, quartz, and partially kaolinized feldspar. Scrap mica, a term often used indiscriminately to describe everything other than sheet mica, will be used to denote the waste product from sheet mica mines and fabricating plants. Both flake and scrap mica are used in the mica grinding plants to produce wet-ground or dry-ground mica, although some flake mica recovered from clay mining operations is fine enough to be marketed without grinding. Until 1930, ground mica was made almost entirely from scrap. From 1930 until 1935 a gradually increasing amount of flake mica was mined, and most of this was sold without grinding. A large percentage of this mica was recovered from clay washing plants. In this type of operation the recovery of any sheet mica was .of secondary importance and was considered a byproduct. North Carolina produces more flake mica than any other state, accounting for 73 pct of the total domestic production.' In the following review of current practice in jig plants, there is no intention to disparage these operations. Within the limitations under which they were built, they are examples of mechanical ingenuity. The term jig plant is a carryover from early practice since there are no jigs in operation at the present time. Current practice, as shown in Fig. 1, is based on successive stages of differential crushing with rolls followed by trommel screens to remove the more easily crushed gangue minerals. The oversize mica product then is usually dried, and passed through another set of dry rolls and a final screen to remove the remainder of the grit. This process is effective in recovering up to 50 pct of the mica in the original ore, the balance being lost in the screen undersize, usually —% in. Jigs and tables were at one time used to treat this screen undersize and were capable of recovering a part of the mica larger than about 60-mesh.V ine mica lost in these plants is normally washed away in streams and can be considered irrecoverable. There are ten or more washing plants in the North Carolina area that are losing approximately 50 pct of the mica in the feed. Since the three cooperating agencies, the Asheville Minerals Research Laboratory of North Carolina State College, the North Carolina Dept. of Conservation and Development, and the Tennessee Valley Authority, are concerned with conservation of minerals, they have investigated means for improving the efficiency of these mica plants. The mica industry has been cooperating fully with the laboratory to establish a more efficient method of recovery for flake mica. Choice of Methods The initial investigation was concentrated on finding a means of reducing the losses from plants now using the conventional flowsheet shown in Fig. 1. To accomplish this it would be necessary to collect the screen undersize products through the plant and remove from them the mica from Vs in. down to

Jan 1, 1952

By A. W. Demmler

RECENTLY, Chaudron,&apos; Montariol,2 and their co-workers published the results of their studies on zone-refined aluminum. They found their material to be capable of recrystallization at —50°C, but gave no data as to the percentage reduction or time required. Their material was found to be practically non-work hardening at room temperature, but after 96 pct cold work at a low temperature and storage in liquid nitrogen it was found to recrystallize to coarse grains in less than 3 hr at 20°C. Recently, a study was made of the room temperature recrystallization characteristics of zone-melted aluminum. An ingot 14 in. in length, with a 3hx3 in. cross section, was made in an extremely high purity graphite boat under an atmosphere of dried commercial argon. It was made by first passing the molten zone along the ingot of 99.99+ pct A1 15 times. At this point, the most impure 3 in. (the end toward which the eutectic forming impurities migrated) were replaced with more of the original starting material, and 15 more traverses were made. Each traverse of the zone along the ingot required approximately 3 hr. Three ingots were prepared in this identical fashion and the chemical analyses were made spec-trographically on two of these ingots, rather than on the one used in this investigation. The analyses were made at 1 in. intervals along the ingot, in duplicate. Over the purest 5 in. of the ingot, which were most important in this investigation, there was found an average composition of <0.00004 pct Cu, <0.0003 pct Fe, <0.0001 pct Si, and <0.0001 pct Mg. In addition, the following elements were not detected spectrographically even in the more impure end of the bar: manganese, zinc, nickel, chromium, titanium, vanadium, lead, tin, boron, beryllium, bismuth, gallium, zirconium, cadmium, antimony, cobalt, and molybdenum. The original ingot was given several cold reductions, with intermediate anneals in order to refine the grains. Owing to the extreme length resulting and the ease of deforming the material plastically, it was cut into eight equal lengths and identified as shown in Fig. 1, with the highest numbered section at the purer end (that enriched with peritectic formers). Section 6 was used in the exploratory work and was found to be of exceptionally high purity, giving more rapid rates of room temperature re crystallization than any previous aluminum studied at the Alcoa Research Laboratories. This fact suggested that the entire midsection of the ingot might be of very high purity. Accordingly, section 4 was chosen for the next study. A portion of it was rolled to cold reductions of 10, 25, 40, 60, 75, and 90 pct at room temperature, and the re-crystallization of each specimen was followed by X-ray pinhole transmission photographs. The other portion received the same treatment, except that both the specimens and the rolls were maintained at 160°F in the process of rolling. The latter ortion was retarded in its recrystallization as compared to the former, probably due to the stress relief effect of the warm rolling. Both of these portions of the fourth section were found to recrystallize at a considerably slower rate than did the sixth section.

Jan 1, 1957

By C. Elbaum

Specimens consisting of several crystals, each with a prescribed geometry and a controlled orientation with respect to both the extermally intposed stress and the highboring crystals, werer deformed in tension at room temperature. It is shown that the influence of a grain boundary on the plastic defolrmation of a mullicrystal depends on the extent to which the presence of the grain boundary, contributes to the necessity 01. multiple slip in the component crystals. MANY investigations were carried out in the past on the plastic deformation of aluminum single crystals, bicrystals, and polycrystals. The various studies of bicrystals aimed primarily at elucidating the influence of grain boundaries on the mechanisms of plastic deformation. In the earlier studies the emphasis was placed primarily on finding the "strength" contributed by a grain boundary. In more recent investigations it became apparent that the grain boundary does not contribute any strength per se but rather acts by influencing the mechanism of plastic deformation in the adjoining grains. The concept thus emerged of the plastic properties of a bi-crystal, and by extension of a polycrystal. depending solely on the mechanism of deformation prevailing in each grain. The contribution of the grain boundaries thus becomes limited to the type of restrictions imposed on each grain by its neighbors. The present investigation of the behavior of specimens consisting of more than two crystals was designed for the purpose of studying the influence of the grain boundary in simple aggregates. The findings of this study further support the concept that the restriction imposed on a deforming crystal by its neighbor constitutes the predominant factor in the plastic deformation of polycrystals. The term "multicrystal", in contrast with single and polycrystals, is used to describe specimens consisting of several crystals. Each one of the component crystals has a prescribed geometry and a controlled orientation with respect to both the externally imposed stress and the neighboring crystals. Two groups of multicrystals were prepared. All the component crystals of both groups of multicrystals had the axial orientation (isoaxial multicrystals) shown in Fig. 2, with the primary slip plane and slip direction both at 45 deg to the specimen axis. In the first group (hereafter referred to as group I) the component crystals were symmetrically oriented with respect to the plane of the grain boundary; the primary slip plane and slip direction were respectively at an angle of 60 and 30 deg to this plane. For the second group (group 11) the axial orientation remained the same and the relative positions of the primary slip plane and slip direction are shown in Fig. 3. EXPERIMENTAL METHODS The material used was aluminum 99.993 pct pure, according to the manufacturer. The specimens were produced by growth from the melt in a horizontal graphite container. In order to maintain the prescribed geometry of the individual crystals of a multicrystal, a technique described elsewhere was used.&apos; The specimens were grown under a small, positive pressure of helium at a rate of approximately 1 mm per min. annealed in air for 24 hr at 640°C and cooled over a period of several hours to room temperature. All the multi-crystals were rectangular in cross-section, 6 by 18 mm (see Fig. 1) and from 150 to 170 mm long. In each group bicrystals, tricrystals and quadru-crystals were prepared as shown in Figs. 1 and 4.

Jan 1, 1961

By C. S. Barrett

The torsional after-effect in polycrystalline cadmium is interrupted by an abnormal twisting when the film is removed by etching. This is accounted for by the pile-up of dislocations beneath anodic or other oxide films during the original twisting, and the relief of the residual stresses from these by elastic and plastic processes during etching. WHEN an iron or zinc wire coated with oxide is plastically twisted and then released, it untwists according to a law of equal increments in equal intervals of log time, but if the oxide is suddenly removed by etching this normal after-effect is interrupted by a transient, and thereafter the untwisting is slower.&apos; Etching may even reverse the strain temporarily. Related effects caused by hydrated oxide films on cadmium in creep tests have been observed by Phillips and Thompson:&apos; definite transient strains caused by the removal of the film from single crystals of cadmium were observed; however, negligible effects were obtained with polycrystalline wires. Pronounced effects of both transient and steady nature were observed by Phillips and Thompson when anodic films 10-4 cm thick were etched off, and weak effects, transient only, occurred with hydrated oxide films 3x10 cm thick such as were formed by standing in water for 10 min. It was estimated that 10.&apos; cm films, formed in water in 1 or 2 min, could be detected in the apparatus of Phillips and Thompson. Since abnormal after-effects were observed by the torsion method equally well with polycrystalline and monocrystalline iron and zinc wires,&apos; it was anticipated that the torsion method would also disclose them in polycrystalline cadmium, in spite of the fact that analogous effects had not been observed in tensile creep tests on polycrystalline zinc by Pickus and Parker3 r on polycrystalline cadmium in tensile studies by Andrade and Randall." Because of its high sensitivity, particularly its sensitivity to surface conditions, the torsion method was thought to merit further study as a method of investigating thin films of various types and the action of various reagents on these films. Materials and Methods Cadmium wires were cold-drawn to a diameter of 0.039 in. from a stock that was determined spectro-scopically to contain 0.05 pct Bi, 0.005 pct Cu, 0.008 pct Pb, and 0.007 pct Si. The wires were cut to about 17/8 in. lengths and were annealed 1 hr in air at 290°C, after which the grain size was such that there were 5 to 7 grains across a diameter. The wires were then mounted as indicated in the insert in Fig. 1, one end being fastened with laboratory wax into a small diameter brass tube and the other end being waxed to a thin glass fiber which supported, on its upper end, a small galvanometer mirror. The wires were waxed with care to avoid straining or annealing, for it was found that the after-effect rate was sensitive to prior cold work in a wire. The assembly was then clamped above a beaker into which the reagent could be poured. The lower end of the wire was held in the hand while the wire was twisted 180"; it was then released immediately. Since precision timing of these manipulations was not attempted, the different wires cannot be compared as to exact rates of untwisting. The length subjected to plastic strain was 15/8 in. The surface coatings studied were those produced by the annealing in air, by anodic treatment of

Jan 1, 1954

By M. F. Goudge, R. V. Tomkins

Sodium sulfate is an important chemical raw material that is being used in ever increasing quantities in modem industry. It comes on the market mainly in three forms: (1) Salt cake (Na2SO4), a relatively crude form of the anhydrous salt containing up to 3 pct impurities, and comprising about three-quarters of the North American production; (2) anhydrous sodium sulfate (Na2SO4), a refined form containing less than 0.3 pct impurities; (3) Glauber&apos;s salt, the decahydrate (Na2SO4.10H2O) containing 55.9 pct water of crystallization. Competing with salt cake from natural sources is byproduct salt cake from a number of industrial operations. For instance there is Mannheim cake resulting from the manufacture of hydrochloric acid by the reaction of salt (NaCl) and sulfuric acid in Mannheim furnaces; rayon cake, a high-quality product, resulting from the process of making rayon by the viscose process; chrome cake from the processing of sodium chromate to dichromate; phenol cake from the manufacture of phenol; also byproduct sodium sulfate resulting from the conversion of lithium sulfate to lithium carbonate; from the processing of sodium tetraborate to boric acid; from converting sodium formate to formic acid; and in the manufacture of cellophane. Sodium sulfate is also obtained as a byproduct in the manufacture of isosebasic acid. In addition strong competition has resulted from imports of byproduct salt cake from the chemical industries of a number of highly industrialized European countries. However in recent years due to technological changes the output of byproduct salt cake is rapidly diminishing and the natural deposits are becoming the most important source of sodium sulfate used in North America. For instance, the production of hydrochloric acid in Mannheim plants has become obsolete and thus the greatest single source of byproduct salt cake will disappear. Also viscose rayon is meeting strong competition from nylon and other synthetic fibers and production of byproduct salt cake from this source may do little more than remain at the present level. These factors together with increasing demand for sodium sulfate point to increased production from natural sources. In 1958, 36 pct of the total United States production was derived from natural sources and in addition 97,000 short tons was imported so that over 40 pct of the total consumption was supplied by natural sources whereas in 1953 the proportion was only 24 pct. The rapid growth in production is shown in Table 1. Principal Sodium Sulfate Minerals There are many minerals in which sodium sulfate is a constituent but those of commercial importance at the present time, and consisting wholly of sodium sulfate in either the hydrous or anhydrous states, are mirabilite and thenardite. Minerals of potential importance but consisting in part of compounds other than sodium sulfate are glauberite in which sodium sulfate is combined with calcium sulfate, and blödite in which sodium sulfate is combined with magnesium sulfate. Mirabilite (Na2SO4.10H2O) the decahydrate, consists of 24.8 pct SO3, 19.3 pct Na2O, and 55.9 pct H20. It is a colorless to opaque, soft, water-soluble mineral with a slightly bitter taste. It has a hardness of less than 2 and a specific gravity of 1.48. It forms long needle-

Jan 1, 1960

By Y. L. Yao

A scale based on existing data for the mutual solid solubilities of metals in binary systems has been compiled. This scale is useful for estimating the relative magnitude of two solubilities, provided that these two metals do not form a continuous series of solid solutions. In his classic work on the theory of metallic solid solutions, Hume-Rothery proposed that, other things being equal, a metal of lower valency should be regarded as more likely to dissolve one of higher valency than vice versa. He called this the "relative valency effect". Later he found that the application of this general principle was limited to the three univalent metals: copper, silver, and gold. In dealing with alloys of these metals with metals of higher valency, Hume-Rothery stated, it is usually found that the solid solution of the univalent metal is of the greater extent.&apos; The question of whether there is a systematic trend in comparing the relative magnitude of mutual solubilities, if valency is not considered a criterion, naturally arises. The present paper proposes a "mutual solid solubility" scale on an empirical basis. The order of its arrangement is determined by the relative magnitude of mutual solid solubilities. Some applications of and inferences from this scale are given. ORIGIN AND SCOPE OF THE SCALE An extensive survey of over 400 binary phase diagrams shows that, with certain exceptions and within certain limitations, metals can be arranged in the following order: Na Zn Cd Ga Bi Ge Sb As Hg Sn Si Mg Li Ba In Tl Pb Al Ca Be Mn Cr Re W Mo Cu V Ta Fe Ru Cb Co Ti Hf Ni Os Zr Ir Pt Au U Rh Ce Pd Ag Th so that a metal higher on the scale tends to have a higher solubility in a metal lower on the scale than vice versa. some experimental solubility data are given in Table I. These data, unless otherwise specified, are taken from Hansen and Anderko.6 Throughout this paper, the term "solubility of A in B" is taken to mean the maximum solid solubility of A in B in atomic percent, while the maximum solid solubility of B in A in atomic percent is called "reciprocal solubility". The exceptions found in the above-mentioned survey are: Al-Ag system, 20.34 at. pct Al in Ag, 23.8 Ag in Al; Mg-Pb system, 5.9 Mg in Pb, 7.75 Pb in Mg; As-Sn system, vanishingly small amount of As in Sn, a large As primary solid solution; Cd-Hg system, Cd in Hg <Hg in Cd; Mg-T1 system, 5(?) Mg in ßT1, 15.4 T1 in Mg; W-Ti system, -21 W in ßTi, -25 Ti in W; Zr-Ag system, probably small amount of Zr in Ag, 20 Ag in ßZr.7 Considering the large number of examples, the exceptions are few. It is remarkable that metals may be so arranged without considering other factors such as size, crystal structure, electronic structure, and so forth. A limitation to the use of the scale is the fact that it cannot be tested for two metals forming a continuous series of solid solutions. It is interesting to point out that when the continuous solid solutions have a miscibility gap the critical composition is

Jan 1, 1961

By G. S. Upadhyaya, A. D. McQuillan

HERE would appear to be a simple relationship between the group number in the periodic table of the early transition metals and the maximum amount of hydrogen which they can absorb.&apos; Thus group IIIA metals (Sc, Y, and La) yield a trihydride in which the metal atoms are on a fcc lattice and the hydrogen atoms occupy both tetrahedral and octahedral interstices. Group IVA metals (Ti, Zr, Hf) form dihy-drides in which the metal atoms are on either a fct or cubic lattice, but in which only the tetrahedral interstices are occupied by hydrogen atoms. In group VA (V, Nb, Ta) the hydrogen-saturated metal attains a composition slightly below that of a monohydride under normal conditions. Finally the metals of group VIA (Cr, Mo, W) do not dissolve appreciable quantities of hydrogen. The manner in which hydrogen solubility disappears on alloying a group VA metal with one from group VIA has previously been investigated.2 It is necessary, in order to obtain a general picture of the reactions of alloys of the early transition metals with hydrogen, to examine a system containing metals from groups IVA and VA in which there must be a change from a fcc to a bee hydride phase. The system chosen for investigation was the pseudobinary system between titanium hydride and niobium hydride. Metallic alloys were prepared by melting iodide-prepared titanium with zone-refined niobium in an argon-atmosphere are-furnace. To ensure homogeneity each alloy was cold-swaged and then heated at 1250°C in a high-vacuum furnace until metallo-graphic examination confirmed its complete homogeneity. Small weighed specimens of the alloys were charged with hydrogen using gaseous hydrogen generated by heating titanium hydride. The apparatus has been described elsewhere.3 Throughout the charging process the hydrogen pressure was kept at about 1 atm while the specimen, initially at 800 °C, was slowly cooled to 150°C over a period of days. The total amount of hydrogen absorbed by each specimen and the room-temperature crystal structure of the hydride powders were determined. The X-ray investigation indicates that the fee hydride phase arises from alloys extending in composition from titanium to 67 at. pct Nb. After a two-phase field lying between 67 and 74 at. pct Nb in which the fee and bee hydrides coexist, all alloys richer in niobium yield a distorted bee hydride. Data derived from parameter measurements are presented in Fig. 1. The atomic volume per metal atom has been plotted against the composition of the initial metallic alloy in order to facilitate comparison of the effects of hydrogen addition in the two phases of different crystal structure. The amount of hydrogen absorbed by each alloy at saturation in terms of the hydrogen to metal ratio and alloy composition is given in Fig. 2. Over the whole range of the fee hydride phase the hydrogen content remains constant, while in the distorted body-centred hydride phase, the hydrogen content increases with increasing titanium content reaching a hydrogen/metal ratio of 1.4 at the boundary of the two-phase region. It seems likely, therefore, that the maximum hydrogen content of the fee hydrides is limited to a hydrogen/metal ratio of 2 because hydrogen atoms

Jan 1, 1962

By R. Simon, L. Yarborough

This paper presents a correlation for predicting the critical pressures of gas-solvent-reservoir oil systems of the type encountered in gas and solvent injection processes. Experimental data from 14 systems were used to develop the correlation which expresses critical pressure as a function of composition, C7+ mol weight, and C7+ characterization factor. Critical pressures predicted by the correlation for the 14 gas-solvent-reservoir oil systems have an average deviation of 2.8 per cent of the experimental values. The correlation war used to study a wide variety of other hydrocarbon mixtures reported in the literature whose critical conditions are in the range of interest in oil recovery work (100 to 280F and 2,000 to 6,000 psia). Critical pressures predicted by the correlation had an average deviation, expressed as per cent of experimental value, of 5 per cent for 20 miscellaneous mixtures from the literature, and 6.4 per cent for I7 methane-butane-decane mixtures reported by Sage and Lucey. INTRODUCTION Predicting critical points of hydrocarbon mixtures is an important part of phase behavior calculations. If the critical point can be predicted for a specific mixture, the separation between the bubble-point and dew-point regions will be defined, and physical properties of the mixture can be calculated by using the principle of corresponding states. Numerous correlations for predicting critical points of hydrocarbon mixtures have been published. Six of these correlationsl-8 were for light hydrocarbons, and two correlations7,8 ere for high boiling-point petroleum distillates. Organick9 And Eilerts" presented correlations which combined the published data from both light and heavy mixtures, and these correlations became the only available methods for predicting critical pressures for wide boiling range mixtures. In the course of the authors&apos; work on secondary recovery by gas and solvent injection, experimental data were obtained for 14 mixtures of dry gas, ethane-propane-butane solvents, and various reservoir oils. The critical pressures and critical temperatures of these gas-solvent-reservoir oil systems were in the range of 1,900 to 4,800 psia and 180 to 265F. The critical pressures predicted for the 14 mixtures by the correlations of Organick and Eilerts had an average deviation from the measured values of about 13 per cent. The authors felt that it was necessary to develop a better correlation for engineering calculations and the resultant correlation, which is presented on Figs. 1 and 2, predicts the critical pressures of the 14 mixtures with an average deviation of 2.8 per cent. The validity of the correlation was tested by applying the correlation to other hydrocarbon mixtures reported in the literature. This subject is discussed later in the paper. The authors feel that there is also a need for an improved critical temperature correlation for gas-solvent-reservoir oil systems. However, developing a critical temperature correlation is a significant study in itself and is not included in this paper. EXPERIMENTAL DATA The compositions and critical points obtained by the authors for 14 gas-solvent-reservoir oil mixtures are shown on Table 1. The methane concentrations in these mixtures varied from 20 to 63 mol per cent. The intermediate hydrocarbon group, consisting of ethane, propane, and butane, varied from 20 to 64 mol per cent, and the concentration of the C,, fraction from 10 to 20 mol per cent. The physical properties of the C,, fraction covered the range from light, paraffinic, nonasphaltic (Mixtures 5, 6, 7, 8, 9 and 10) to heavy, aromatic, and asphaltic (Mixtures 13 and 14).

By F. von Gemmingen, E. J. Fasiska, L. Zwell

EARLIER studies of the dependence of creep on structure1 and of the dependence of creep rupture on creep behavior2 did not include detailed discussion of the phases present in the specimens under examination. It is of interest to determine the nature and amounts of such phases present since it is well known that these are dependent on composition, heat treatment and creep conditions.3 This investigation has therefore been undertaken to identify these constituents and to determine their relative amounts. This report presents the results of this investigation and describes an improved "extraction replica" technique developed in the course of the work. The composition of the Type 316 austenitic stainless steels studied in this investigation is given in Table I. The specimens were solution treated at 2000°F for 1/2 hr and water quenched. Those specimens subjected to prestrain at room temperature Methods for extracting precipitate particles from materials for electron and X-ray diffraction analysis have been described by Fisher,4 Smith and Nutting: and Booker and coworkers.6&apos;7 Electrolytic extraction methods have been described by Andrews and Hughes.8 The first two methods have been used at this Laboratory, but have not proved satisfactory for many problems requiring X-ray diffraction analysis. It has been difficult to remove the replicas or to avoid tearing them during removal. These difficulties are overcome by backing the replica with a water-soluble plastic such as Dupont 51-05 Elvanol (polyvinyl alcohol). The backing increases the thickness of the replica so that it can be mechanically stripped from unloosened particles without folding or tearing. This procedure eliminates the stripping of wet replicas, which usually have a low tear strength. By stripping replicas after drying, it is possible to extract partially loosened particles which otherwise would remain imbedded in the metal. The modified method is as follows: after the specimen is polished, it is etched for 60 min in modified glyceregia consisting of 30 ml glycerol, 7 ml nitric acid, and 4 ml of hydrochloric acid. The sample is then washed, air dried, and coated with a 20 pct Baker and Adamson 1611 collodion (85 pct amyl acetate by volume) film. After the collodion film is dry (about 15 min), the sample is again etched in the modified glyceregia for 50 min, washed with isopropyl alcohol (to prevent dissolving the collodion) and air dried. A very thick coat of polyvinyl alcohol (about 50 pct solution "Elvanol Dupont 51-05" in water) is poured over the sample and is permitted to dry for about 24 hr. The composite film containing the precipitates is then stripped from the specimen and floated, polyvinyl alcohol side down, in water (at about 50°C) until the polyvinyl alcohol dissolves. This usually takes about 15 min. Should any of the polyvinyl alcohol remain on the replica, it does not give a crystalline diffraction pattern and therefore does not hinder identification of the precipitates. The extraction replica, floating in water, is picked up on a glass fiber and mounted in the Debye-Scherrer camera for X-ray diffraction analysis. Concentration of the etchant, and also etching time, had to be increased for several of the samples. Fig. 1 shows two extraction replicas taken from different areas of spec. M74-37; X-ray analysis showed a strong diffraction pattern of M23C6 and a medium one of u phase. A

Jan 1, 1962

By R. M. Rose, D. P. Ferriss, J. Wulff

Single crystals of tantalum were grown by multipass zone melting in an electron beam apparatus. Tension tests of these crystals at 4.2 x 10&apos;* per sec-gave a resolved louler yield stress of 7300 psi at with a chisel edge; total uniform deformation increased from 1 to 2 pct at 77°K to over 20 pct at 300°K. This, and slip traces, indicated that deformation is more inhomogeneous at lower temperatures. Deformation occurred exclusively by slip in <III> directions, on planes in the <111> zones. Cross slip was frequent, particularly for those orientations where the resolved shear stress on the cross system was comparable with that on the primary plane. The existence and magnitude of the upper yield point were found to be sensitive to orientation. This effect was related to the circumvention of dislocations which were "locked" by interstitial atoms, by double cross slip, or composite slip, of screw dislocations. Prestrainirg at 300°K did not remove the upper yield point in subsequent tension at 77°K. Also, this treatment was found to cause yield points, where none existed for the unprestrained material. This behavior was also rationalized in terms of the circumvention mechanism. The mechanical properties of polycrystalline tantalum have been investigated by several workers,1"4 and may be summarized by pointing out the following features: a) Sharp rise of yield stress with decreasing temperature below room temperature. b) Response to strain aging at 300" to 400"C. c) Yielding with upper and lower yield-point phenomenon at and below room temperature. d) Low strain hardening below room temperature. e) Reluctance to twin except at very high strain rate. Furthermore, tantalum is ductile at ordinary strain rates as low as 4.2"K.&apos; This feature, in particular, makes tantalum unique among the high melting point, bee transition metals of Groups V and VI in the periodic system. Therefore, a more fundamental and detailed knowledge of the low-tempera- ture deformation of tantalum is required. Since high purity and the absence of grain boundary effects make such a study most productive and unambiguous, the method of electron beam zone melting was selected for the preparation of test specimens. This technique has the further advantage that crystals may be seeded in order to obtain any desired orientation. EXPERIMENTAL The electron beam zone-melting equipment was constructed as a modification of that described by Calverley, Davis, and Lever? All crystals were made by three passes of the molten zone at 4 mm per min to achieve an optimum purity commensurate with economy of time and material. Table I reports the chemical analyses of the starting and refined metal. It will be noted that there remain some 50 to 70 wt ppm of interstitial elements, while all substi-tutional elements have been removed by evaporation. Tungsten is picked up by evaporation of the cathode filament wire. Crystal seeding was normally successful within 3 deg, and the orientation of all crystals are given in the standard stereographic triangle in Fig. 1. Tensile bars were prepared from the crystals by centerless grinding to the shape in Fig. 2. Specimens were then electropolished to remove 10 pct of the diameter in order to remove worked material and to prepare a metallographic surface for subsequent deformation trace observations. All specimens were held in the split bushing grips as indicated in the cross section view of Fig. 2. All tests were made at a strain rate of 2 112 pct per min in an Instron testing machine.

Jan 1, 1962

By C. A. Hartnagel

The production of petroleum in New York in 1940, totaling 4,999,000 bbl., was only slightly under the amount produced in each of the previous three years. The year 1940 started auspiciously with a posted price on Jan. I of $2.75 a barrel. Four price reductions, beginning in May, resulted in August in a low of $1.85 a barrel, after which two increases brought the year&apos;s closing price to $2.15 a barrel. The favorable crude price at the beginning of the year stimulated an increased drilling program, especially in the water-flooding districts. In the Allegany County region, which accounts for about two-thirds of the state&apos;s oil production, 886 wells, including water-intake wells, were drilled; 200 more than in the preceding Year. During the closing months of the Year there was a marked decline in the number of wells drilled. The unfavorable position in which the industry found itself before midsummer was due largely to the loss of export markets for its high-grade lubricants, constituting approximately 25 per cent of its business. As a result of this situation, runs to refineries were curtailed as much as 30 Per cent at the middle of the Year. Improvement in market conditions toward the end of the Year found the stocks of available crude at an almost record low. Deep DRILLING with the gradual exhaustion of some of the important natural and flood-oil-produc-ing areas of the Allegany and Bradford pools, overproduction will not be a serious problem in the future. The possibility of finding new territory or deeper producing sands has been further lessened by the drilling of additional deep wells for gas in and about the present oil fields. Many of these wells drilled to the Oriskany sand-stone were over 4000 ft. deep and have tested the entire thickness of the Devonian formation, the upper 2000 ft. of which contain all the important oil-producing strata in the state. Water-flooding It is thus evident that the problem of the New york oil producers is not one of find-ing new supplies but of obtaining as much 6 oil as possible from the old developed fields that during the 60 years of their life have 1 produced I 3o,ooo,ooo bbl. of oil. Although a few floods were in operation before I9I9, when the production of oil by flooding was 1 made legal, the output for that year amounted to only 85I,000 bbl. From 1919 I on there has been an almost constant increase, which during the past four years has averaged well above 5,000,000 bbl. annually. During the last 22 years, which constitutes the period of important flooding operations, 651337,000 bbl. of oil have been produced in the state. Careful estimates indicate that between one-third and one-half of the oil fields are being flooded or are already watered out. Some of the flooded and watered-out areas include territory with unusually thick sands, which were highly productive during the early history of the fields. From a recent study of operations in the New York oil fields, it is estimated that about 65,ooo,oo bbl. of oil

Jan 1, 1941