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By W. P. Heineken, A. T. Child

This paper presents the results of a series of experiments made in the metallurgical laboratory of Columbia University, New Pork City. The object of the investigation was to determine, as far as possible, the changes in micro-structure and physical properties caused by short periods of heat-treatment and the longer malleable cast-iron process. It was proposed to do this by means of micro-photographs, heating- and cooling-curves, and tensile tests after the various heat-treatments. I. Micro-Constituents of Iron and Steel. The list of the micro-constituents of iron and steel has grown till now it includes seven different substances, called ferrite, cementite, pearlite,* martensite, austenite, sorbite and troosite. Only the first five of these are mentioned in this paper, to facilitate the understanding of which, the following brief definitions are given: 1. Ferrite (named by Prof. Howe) is, chemically, iron free from carbon. It is the softest of the constituents, and is not colored by etching, except when long-continued. Under the microscope it is easily determined by its regular polygonal etructure; or, if structureless, as in malleable cast-iron, by the ease with which it is scratched. Ferrite appears in mild steel in small amount, in grey cast-iron, and in malleable cast-iron. 2. Cementite (also named by Prof. Howe) is now generally conceded to have the formula Fe3C. It is the hardest of the micro-constituents, having the hardness indicated by 7 of the mineralogical scale; and hence it is always left in relief after

Jan 1, 1901

By John D. Sullivan

Leaching of copper ores is a comparatively old art, probably dating back to medieval times. The leaching of mixed oxidized-sulfide ores, however, is modern. The first modern plant leaching mixed ores was at Ajo, Ariz., where commercial operations commenced in 1917. While the ore at Ajo was primarily oxidized there was always some sulfide present. The Inspiration leaching plant, which was put in operation in 1926, may be considered the first plant constructed for the extraction of both sulfide and oxidized copper. The pioneers in leaching mixed ores had a difficult task before them since they had very little fundamental data on the chemical and physical factors of leaching. For the very large amount of painstaking experimental work that was done before building the Ajo and Inspiration leaching plants the reader is referred to the original articles.' For a period of several years the writer worked on problems connected with the chemistry and physics of leaching mixed oxidized-sulfide ores. This paper summarizes the experimental work and discusses various factors involved in leaching ores. It also presents many data heretofore unpublished. Among the new data are those on chrysocolla, pages 518 to 519, inclusive; dioptase, page 519; covellite, page 529; virtually all those on chalcopyrite, pages 531 to 533, inclusive; enargite, page 533; and tetrahedrite and tennantite, pages 534 and 533. The oxidized copper minerals of commercial importance in American ores are azurite, Cu3(OH)2(CO3)2; malachite, Cu2(OH)2CO3; chrysocolla, CuSi03.2H2O; tenorite (or melaconite), CuO; and cuprite, Cu2O. Dioptase, CuSiO3.H2O is less common. Brochantite, CuSO4.3Cu(OH)2, while the chief mineral in the ore at Chuquicamata, is not of major importance in the United States. Metallic copper, while chemically not so, is frequently classed as an oxidized mineral of copper. The most important sulfide minerals are chalcocite, Cu2s; covellite, CuS; bornite, Cu5FeS4; and chalcopyrite, CuFeS2. Less important complex sulfides are enargite,

Jan 1, 1934

By G. Ansel, J. O. Betteron

THE PURPOSE OF THIS PAPER is to give a brief picture of present day magnesium rolling practice, to elaborate on laboratory and development rolling experiments; and finally, to discuss the possible Future rolling of magnesium. The present production practice is so varied between various mills that it can only he concluded that no single producer is now using a process that is outstandingly superior to others. In view of this, only the general features of present day production practice have been presented and attention is focussed on the results of laboratory find development rolling of magnesium-base alloys as indications of the Future trend of magnesium rolling. MAGNESIUM ROLLING LITERATURE The literature relating to magnesium rolling is divided into three groups: the deformation mechanisms of the hexagonal magnesium crystals, the metallurgical aspects and laboratory type experiments in rolling, and finally, the articles on production rolling methods. This literature was reviewed and is summarized below. In the first group of references, the existence of basal slip in magnesium single crystals was shown by Schiebold and Siebel1 and of {102} twinning by Mathewson and Phillips2, Schmid3 predicted and partially established {101} slip at hot working temperatures. Bakarian and Mathewson4 confirmed the above and eliminated {101} twinning as a probable deformation mechan-

Jan 1, 1948

By Knut L. Sandvik, Aage Solbakken

it is an established fact that the collecting properties of xanthates and anionic collectors are dependent on the hydrocarbon chain length. This is ascribed to the greater adsorption densities caused by increasing the xanthate chain length. As batch flotation tests showed similar trends for amines, an investigation of the adsorbing properties of amines was undertaken. Because earlier investigations showed adsorption densities for dodecylamine salts on quartz varying as much as 20 times under apparently similar conditions,1-4 it was decided to make a survey of the changes in adsorption density due to the drying conditions of the quartz. EXPERIMENTAL PROCEDURE The quartz, handpicked in the pegmatite quarries of Iveland, Setesdal, had the following composition: SiO2 99.81, A12O3 0.01, Fe2O3 0.05 and loss by ig-

Jan 1, 1969

By Byron W. Cheever

While engaged in experimenting with the usual methods for estimating phosphorus in iron and steel, it occurred to me that potassium chlorate might be used to oxidize the carbon, and thus avoid the tedious and vexatious evaporations necessary for successfully carrying out the usual methods. After many trials, the following plan was adopted : Take, for analysis, of Bessemer or other low-carbon steels, from 3 to 5 grammes; of crucible steel, 10 grammes; of pig-iron, 1 to 5 grammes, according to the percentage of phosphorus supposed to be present. Of iron, high in phosphorus (1 per cent.), take 1 gramme. Place in a No. 4 evaporating dish the amount of iron or steel decided upon, cover with a funnel which will just fit inside the dish, and then add gradually HNO3, (1.20 specific gravity), using 12 C.C. of acid for each gramme of steel or iron taken. (A larger quantity of acid will be required for small samples.) When the full amount of acid has been added, and the violent action has ceased, place the evaporating dish on a sand-bath, add 10 C.C. HNO3, (1.40 specific gravity), and boil till the bulk of the solution is reduced about onehalf. Then add 10 C.C. HNO3, (1.40 specific gravity), continue the boiling, and add from time to time, during the next 15 minutes, small portions of pulverized KCIO3, till about 2 grammes have been added. (If the solution shows signs of going dry, more strong acid must be added.) This will precipitate the manganese, with some iron. Sometimes it happens that the manganese does not come down readily, and more KCIO3, or further concentration, or both, will be required. The process is not complete till the manganese is precipitated, which may be known by the appearance of a dark, mirror-like deposit on the dish, at the edge of the solution. Boil the solution 5 minutes after the last addition of KCIO3, and then add cautiously (to prevent sudden explosions) 5 C.C. strong HCl. This will dissolve the precipitated manganese and iron. Continue the boiling till the chlorine is all expelled, adding from

Jan 1, 1885

By Chandler Morse

RENEWABLE VS. NONRENEWABLE NATURAL RESOURCES Nonrenewable resources, such as minerals, are the inevitable center of attention in discussions of depletion and exhaustion. Nevertheless, it may well be proper to regard some nonrenewable resources as not subject to exhaustion, and renewable resources may sometimes be treated as if they were finite stocks. Thus, the availability of nonrenewable resources is not and probably never will be known completely Chap. 2.5A, and therefore is not subject to firm predictions concerning exhaustibility. Moreover, because exploration and discovery are more or less continuous processes it is often appropriate to regard mineral supplies as flows, and to treat the estimated reserves as working capital, an inventory, continually depleted by use and augmented by discoveries.23 The aggregate economically exploitable stocks of a given mineral are seldom estimated (or estimatable) with precision, as Chap. 2.5A shows, and even when they are, forecasts concerning years of remaining life can be and often are falsified by changes in one or more of the multidimensional conditions of supply and demand; or the productive services formerly derived from an exhausted stock may continue to provided without material impairment by one or more substitutes b Conversely, the renewable resources are all subject to depletion when the rate of use exceeds the natural or induced rate of replenishment, and cases of exhaustion or near exhaustion, as through soil erosion, overcuttmg of forest lands, and overfishing, are rather common c Where exhaustion is a clear possibility the resource may either be exploited on a consciously adopted "sustainable yield" basis or be treated as an exhausting asset." In some cases, conscious treatment

Jan 1, 1976

By C. Schlumberger, M. Schlumberger

The object of this paper is to clarify the idea, so important when exploring by potential methods, of the depth of investigation attainable by electrical measurements. After defining, with some precision, .the term "depth of investigation'' in geophysics, the authors show how it is possible to regulate this depth in potential methods and to obtain an 'electrical drilling" from surface observations. They consider also the difficulties encountered in deep measurements and indicate how it is possible to reach greater depths than those having an industrial interest. Depth of Investigation The term, depth of investigation, in its general sense, is easily understood. For instance, a driller who can pull cores from a depth of 2000 m. is capable of working, with accuracy, to that depth. By means of a properly placed drill, he may locate an orebody at a depth of 1999 m., however small this orebody may be. On the contrary, the term as used in geophysics requires precise elaboration. As a matter of fact, no geophysical method, irrespective of the physical property studied (density, magnetic permeability, conductivity), can discover a very small body at a great depth because, in practice, the physical parameter upon which such a geophysical method is based is never regular enough, throughout the ground, to distinguish the feeble anomaly caused by the small, deep-lying body from the numerous anomalies due to irregularities of the encasing terrains. Aside from this question of the ratio between the size of the body being hunted for and its depth of burial, a second factor plays its role in the possible depth of investigation; that is the difference, for the parameter under consideration, between the body and its surrounding material. The greater this difference, and the more homogeneous the encasing terrains, the greater is the possible depth of investigation. This being generally established for all geophysical methods, it is possible to distinguish two main classes of these methods, from this same point of view

Jan 1, 1932

By M. J. Marcinkowski, A. Szirmae, R. M. Fisher

Room -temperature hardness measurements obtained from single and polycrystalline samples of a 47.8 at, pet Cr-Fe alloy which were aged for various times al 500°C show a two-fold increase over that of the unaged alloy after annealing for 1000 hr. A detailed examination of the deformation markings in the neighborhood of the hardness imbressions reveals that twinning becomes an increasingly more important mode of deformation as aging proceeds. this observation is shown to be inconsistent with the Proposals that the transformation is eve of order-disorder On the other hand, the results are in agreement with previous observations of Fisher et al. of a coherent chromium-rich precipitate which forms in an iron-rich matrix as a result of a miscibility gap in this alloy system as proposed by Williams . Using the coherent precipitate hypotlzesis as a model, a detailed analysis of the various possible strengthening contributions to both the slip mid twinning stresses is made. In the case of' slip, lattice friction within the chromium-rich phase and the chemical energy associated with the interface between the two phases contribute about 60pet to the total strength. The contributions from coherency strains and modulus differences are thought to contribute the remaining 40 pet of the strength but are difficult to evaluate because of uncertainties regarding the flexibility of the dislocation line. All of the factors have nearly the same or else a smaller effect on the twinning stress in the aged alloy. Twinning is never observed in the unaged alloy because the twinning stress is much higher- than that for slip. With increased aging times, the various contributions to the total stress for both twinning and slip increase, but most of those for slip increase much more rapidly, so that, in the fully aged alloy, it surpasses the stress for twin propagation. When a twin is nucleated by the chance occurrence of an internal stress concentration during a test, the subsequent twin burst results in a low hardness reading. FeRNTIC Fe-Cr alloys from about 15 to 80 at. pet Cr content show considerable change in properties such as hardness, electrical resistivity, saturation magnetization, and so forth, after aging in the vicinity of 500°C.* The most marked change is a large increase in hardness accompanied by a sharp decrease in ductility, so the phenomenon has often been referred to as the 475°C (885°F) em-brittlement problem. Changes in microstructure are rather subtle and most investigators have not been able to observe any X-ray diffraction or metal-lographic changes during aging. There is little doubt that the phenomenon is inherent to the Fe-Cr binary system and is not directly related to the formation of a phase. Two distinct schools of thought have developed during the past decade concerning this problem. Masumoto, Saito, and sugiharal have concluded, from their own specific-heat measurements, that atomic ordering occurs in this temperature range. Pomey and Bastien2 have also attributed the changes in physical properties with aging in the neighborhood of 500°C to atomic ordering. In addition, Takeda and Nagai3 claimed to have found X-ray verification for superlattices corresponding to the compositions FesCr, FeCr, and FeCr3. However, all known attempts to observe superlattices in Fe-Cr alloys using neutron diffraction, which should be much more sensitive, have been unsuccessful. These have been reported by Shull et al.4 for 25 at. pet Cr, williams5 for 75 at. pet Cr, and Tisinai and samans6 for a 28.5 at. pet Cr. steel. The second and more prevalent opinion ascribes the 475°C embrittlement phenomenon to the formation of a coherent precipitate due to the occurrence of a miscibility gap in the Fe-Cr system below about 550°C. This latter concept was first indicated by the results of Fisher, Dulis, and Carroll,7 who were able to extract fine particles about 200Å in diameter from samples of 28.5 at. pet Cr steels aged from 1 to 3 years at 475°C. The extracted material was found to be nonmagnetic, to have a bee structure with a lattice parameter between that of iron and chromium, and to contain about 80 at. pet Cr. Williams and paxton8 and williams5 confirmed these results and first explicitly proposed the existence of a miscibility gap below the a region in the equilibrium diagram. Alloys aged within this gap

Jan 1, 1964

By Paul Rhedey

Various commercial pelroleum cokes were heat-1,reated at temperatures between 500° and 1500°C, in a nitrogen atmosphere, in laboratovy induction furnaces. The rate of tenlperature rise was varied betzveen 10" and 300°C per min, or the green cokes were flash-calcined, orv a combination of heating rates was used. Changes in the rate of heating had only negligible effects on the degree of' calcination as characterized by mean crystallite thickness and the chemical properties of the calcined coke. The physical structure of the cake was however significantly affected when rate of heating during calcination exceeded 50°C per min over the temperature range of 600° to 900°C. Surface-accessible porosily increased with the .rate of temperature rise, and this was accompanied by a change in pore size distribution. Source and properties of the green coke also had an influence on the structure of the calcined coke. The evidence presented suggests a similar mechanism of porosity development in petroleuiiz coke during calcination in industvial equiplnenl, such as rotary kilns. An increase in surface accessible povosity incveased the pitch binder requirement when the coke was used as aggregate in Soderberg paste. A correlation was established between calcined coke porosity and paste binder requiremenl. ManY results have been published on the changes of properties of petroleum coke during calcination, such as chemical composition, real density, electrical resistivity, crystallite and pore structure. The correlation of these properties with temperature of calcination and time at maximum temperature has been rather well established in both laboratory and pilot plant experiments. Surprisingly little attention has been given however to the effect of calcination conditions, such as rate of temperature rise or furnace atmosphere, on the chemical and structural properties of the calcined coke. It has been observed that petroleum coke, when calcined in industrial equipment, acquires higher porosity and lower real density than those attainable in laboratory furnaces at apparently identical calcina- tion temperature and soaking time. This paper describes a study of the effect of rate of heating during calcination on calcined coke properties using green petroleum cokes of different volatile matter, hydrogen, and sulfur content. An attempt was made to correlate the changes in coke structure with the flowability of anode paste of the type normally used in aluminum reduction cells. EXPERIMENTAL Petroleum Cokes Used. In the study of release of volatile matter and sulfur during calcination and the effect of rate of heating on calcined coke properties two delayed cokes of different sulfur contents were used. The results of analysis of the green cokes are given in Table I. In the study of the effect of flash calcination thirty-six commercial petroleum cokes from twelve different refineries were used with a range of properties shown in Table 11. Calcination Conditions. Calcination experiments were carried out in a laboratory induction furnace. In each run a 200-g sample of dry green coke sized to 10 by 65 Tyler mesh was calcined in a graphite crucible. The crucible containing the sample was placed in the middle of a stack of eight others filled with metallurgical coke to reduce temperature gradients within the sample. Temperature was measured by two Pt, Pt-10 pct Rh thermocouples and controlled by a Celectray instrument. The two couples generally agreed within 5°C. In the study of volatile matter and sulfur release the samples were heated to temperatures in the range of 500" to 1500°C at a rate of 10°C per min in a nitrogen atmosphere and held at the final temperatures for 30 min. In the study of the effect of heating rate on calcined coke properties the desired rates between 10' and 300°C per min were obtained by manually adjusting the power input. Flash calcination was carried out by dropping 100 g of the green coke into the graphite dish preheated to the calcination temperature. Because of the small heat capacity of the furnace the coke was introduced in 20-g portions at a time. For this purpose a 2-in.-long nipple between two 1-in. gate valves installed on the top flange of the furnace served to provide a gas seal while feeding coke to the furnace. It was estimated that the temperature of the coke reached that of the furnace at a rate of approximately 1000°C per min. Holding time at final temperature was also 30 min. Calcined Coke Proper- Determined. Porosity was determined on 20 by 35 Tyler mesh samples using an Aminco-Winslow mercury pressure porosimeter with an operating range of 1.8 to 3000 psi absolute pressure (100 to 0.05 p pore diameter range).' Apparent density was obtained by the mercury poro-simeter. It represents a particle density of the 20 by

Jan 1, 1968

By R. W. Raymond

THE absence of a convenient glossary of terns connected with mining and metallurgy has long been felt by the general public. It is to meet this want, not to furnish a technical manual for experts, that the following glossary has been prepared. It originated in an attempt on my part to revise for publication the manuscript of a compilation prepared from the appendix of Yale's work on Mining Titles and one or two other sources, to serve as an appendix to a new work on mining law, about to be published by Mr. H. N. Copp, of Washington, D. C. This revision soon assumed, contrary to my original intention, the proportions of a reconstruction ; and with the consent of Mr. Copp, and for the purpose of receiving from my fellow-members valuable aid, I presented my still incomplete work as a paper at the Lake Superior meeting of the Institute, inviting from any quarter suggestions of new terms or better definitions to be incorporated in the glossary before its final publication. This invitation was so widely and generously responded to, that I cannot undertake to make in this place' individual acknowledgments to those members of the Institute, and professional colleagues outside of it, who hays favored me with ' assistance and advice. The labor bestowed upon this paper since its presentation, at the Lake Superior meeting has considerably exceeded that of its first preparation, as

Jan 1, 1881

By Fred Bond

This paper is a continuation of two earlier papers,1,2 and presents new data on the grindability of various ores and other materials-the results of several years of intermittent research work on the nature of grinding and interpretation of test results. It is divided into five parts: 1. The tabulated results of several hundred grindability tests on a wide variety of ores. 2. A method of correcting screen analyses and calculating from them the surface and other properties. 3. A description of a. new method of measuring the "surface energy" of in ore by pendulum impact tests. 4. Test results. 5. A general discussion of the test results and their application to grinding problems.

Jan 1, 1938

By C. A. Herbert, C. M. Young

WithIn the past few years, considerable development has been made in the coal-mining industry in Illinois and Indiana and it is the purpose of the authors to record its most important phases. Perhaps the two most striking features are the entry into the producing fields of certain large consumers of coal and the magnitude of some of the new operations. Mines are now being equipped by the Chicago & Northwestern R. R., the Chicago, Burlington & Quincy R. R., the Standard Oil Co., of Indiana, and the Union Electric Light & Power Co. of St. Louis. Besides, the U. S. Steel Corpn. has increased its coal-mining activities by commencing operations on its large holdings northeast of Benton, Franklin CO., Ill. Until recent years, the supply of coal has commonly been adequate and prices have generally been favorable, especially to large consumers, as the magnitude of their purchases enabled them to obtain satisfactory quotations from producers. In fact, most consumers of coal have believed that they could buy their fuel more satisfactorily in the open market than they could produce it themselves. The entry of the United States into the war was accompanied by various disarrangements of industrial conditions, and a demand for coal in excess of the supply seemed likely to be experienced for an indefinite period. Under these circumstances it seemed that the greatest assurance of a supply of fuel was its production by the operation of mines. In the case of the Chicago & Northwestern R. R. and the U. S. Steel Corpn. the production of coal has been carried on for many years with satisfactory results, but the C. B. & Q. R. R., the Union Electric Light & Power Co. and the Standard Oil Co. of Indiana had not been producers of coal, at least in this district. Apparently the most impressive feature of the newest mines is their capacity, for in some cases it is planned that production shall be in the neighborhood of 1000 tons per hr. There are mines now in this field having nearly that output, but these were not planned for such output; in fact, when the shafts were sunk and the machinery installed it was generally supposed that the daily outputs would be only in the neighborhood of 4000 to 5000 tons. Incidentally, there has risen

Jan 1, 1920

NEW MEMBERS The following list comprises the names of those persons who became members during the period Sept. 10, 1916, to Oct. 10, 1916. BLOOMFIELD, EDWIN CHARLES, Min. Engr., 1012 Standard Bank Bldg., Vancouver, B. C., Canada. BRINGS, HENRY, Min. and Met. Engr., Chief Engr., and Geol., Mollet-Mesrine, 1212 Mills Bldg., El Paso, Texas. CHASE, MARCH F., Vice-Pres., Commercial Acid Co., 1906 Boatmens Bank Bldg., St. Louis, Mo. CUMMINGS, ALVIN M., Asst. Mine Supt., Witherbee, Sherman & Co., Inc., Mineville, Essex Co., N. Y. DOUGLASS, GEORGE M., Genl. Safety Inspector, Amer. Smelt. & Ref. Co. 120 Broadway, New Fork, N. Y. EMRICH, CLARENCE T., Chief Chemist, Old Dominion Copper Min. & Smelt. Co., Box 1163, Globe, Ariz. GARDANIER, SUTTER ALBERT, Assayer, Mgr., Douglas Assay Co., Douglas, Cochise Co., Ariz.

Jan 10, 1916

By D. S. Bloom

RECENTLY a report has been published on an investigation of the MO-RU system by E. Raub.' In this report it is stated that below approximately 1200°C the system consists of two terminal solid-solution phases and the intervening two-phase field; at 1200°C and above, an intermetallic compound labeled Mo,Ru, makes an appearance. Along with some other little known systems in which it was considered possible for a u phase to form, the Mo-Ru system had been under investigation in this laboratory. Since molybdenum and ruthenium have very high melting points and also since ruthenium is expensive, the investigation was confined to X-ray diffraction by sintered powder compacts. The compositions which were studied were (in atomic percentages): 75 Mo-25 Ru, 67 Mo-33 Ru, 50 Mo-50 Ru, and 25 Mo-75 Ru. All compacts were made from the pure powders, and no chemical analyses were attempted. Each compact weighed about 5 g. All annealing was done in evacuated Vycor capsules, and even though the capsules completely collapsed at 1250°C, they still admitted no air. The results of this investigation in general corroborate the work of Raub. Up to 1150°C the two terminal solutions and the intervening two-phase field were found, and at 1200°C and above an intermetallic compound was found. However, the composition limits of the compound were estimated to lie close to 70 atomic pct Mo rather than 62.5 atomic pct Mo as Raub had reported. At least the X-ray diffraction results indicated that the 75 atomic pct Mo specimen consisted of the molybdenum solid solution plus the compound, while the 67 atomic pct Mo specimen consisted of the ruthenium solid solution plus the compound and the equiatomic composition contained only very little of the compound. The most interesting observation, however, was that the diffraction pattern of the compound was similar to that of the well known u phases, except that unusually large lattice constants were indicated. The d-values, or interplanar spacings, of the diffraction lines (as produced by filtered copper KCX radiation) of the compound are given in Table I, as determined from specimens annealed at 1250°C for 9 hr and then quenched in water. Also shown are the lines of the Mn-Mo u phase as given by Decker, Waterstrat, and Kasper,' the lines of the Fe-Mo a as given by Goldschmidt," and the lines of the Mo-Ru phase multiplied by constants in order to make comparison with the Mn-Mo and Fe-Mo patterns easier. These results indicate that the compound in the Mo-Ru system is apparently isomorphous with the other o- compounds. The rather large lattice constants of the Mo-Ru a phase are acceptable in view of the comparatively large size of the constituent atoms. The data in Table I for the Mo-Ru compound check quite well with those given by Raub, not shown here, though there are some discrepancies between the two sets of data in the estimated intensities of a few lines. Although very little is known at present about this u phase, there are some things which may be pointed out, mainly in comparison with other better known u phases. Even though molybdenum and ruthenium are in the same columns in the Table of Elements as chromium and iron, respectively, the Mo-Ru u phase contains much more molybdenum than ruthenium, while the Cr-Fe u phase centers around or very nearly around the equiatomic composition; furthermore, the Mo-Ru u is stable only above approximately 1200°C, but the Cr-Fe u is stable only below about 825 °C. With respect to its being unstable below 1200°C, the Mo-Ru u is similar to the other binary molybdenum u phases in the Co-Mo and Fe-Mo systems. Similar to the latter two systems, the Mo-Ru u apparently exists over a rather narrow composition range, whereas the Cr-Fe u at lower temperatures is stable over a much wider composition range. The Mo-Ru u thus is closer to the other molybdenum u phases than to the Cr-Fe cr phase. The most striking feature of the Mo-Ru u phase, however, is the absence of any of the transition elements of the First Long Period.

Jan 1, 1956

By R. S. Dean

The commercial production of electrolytic manganese on a small scale commenced in 1939. The writer made a short report on the progress of production and utilization in Mining and Metallurgy for January 1941. Progress during the last two years, naturally, has been more rapid. In June 1940, Congressman (now Senator) Scrugham presented a proposal to Congress for an appropriation authorizing erection of a pilot plant for " the production of metallic manganese by electrolytic or other means." As a result of this, a pilot plant, having a capacity of a few hundred pounds per day was built at Boulder City, Nev. Subsequent appropriations permitted expansion of the plant to about a ton per day. Much has been learned in this plant about electrolytic manganese, and the product even in its small way has found war uses of considerable importance. Meanwhile, the Knoxville plant of the Electro Manganese Corporation, the sole commercial producer, was expanded to about 4 tons per day to supply needed material for the war program. Other proposals for commercial plants have not been favorably received by the War Production Board. The Bureau reported on one such proposal by the American Alloys and Chemical Corporation. Practice at BouldeR City The present practice, as carried out at Boulder City, which is being described in more detail in a current paper by the Bureau staff at Boulder City, starts with a manganese dioxide ore containing about 20 per cent manganese. Currently this ore comes from the Three Kids deposit near Las Vegas. The steps for the production of electrolytic manganese, in general, are as follows: 1. The manganese in the ore is reduced to MnO. 2. The MnO is dissolved from the ore in spent electrolyte, which contains about 38 to 47 grams per liter of free sulphuric acid, 135 grams per liter of ammonium sulphate, and 10 to 12 grams per liter of Mn as sulphate. In the leaching step the manganese is built back up to 32 to 36 grams per liter of Mn as sulphate; the pH is adjusted to neutral by means of gaseous ammonia and passed through thickeners. 3. The electrolyte is purified by adding H2S, which precipitates the heavy metals. After filtering, ferrous sulphate is added to the solution and oxidized with air and the solution is filtered and clarified on a precoat filter. 4. The purified catholyte is electrolyzed in a diaphragm cell using stainless-steel cathodes and lead-silver anodes. The current density is about 45 amp. per sq. ft. Current efficiencies of 60 to 65 per cent are regularly obtained.

Jan 1, 1944

By R. S. Dean

The commercial production of electrolytic manganese on a small scale commenced in 1939. The writer made a short report on the progress of production and utilization in Mining and Metallurgy for January 1941. Progress during the last two years, naturally, has been more rapid. In June 1940, Congressman (now Senator) Scrugham presented a proposal to Congress for an appropriation authorizing erection of a pilot plant for " the production of metallic manganese by electrolytic or other means." As a result of this, a pilot plant, having a capacity of a few hundred pounds per day was built at Boulder City, Nev. Subsequent appropriations permitted expansion of the plant to about a ton per day. Much has been learned in this plant about electrolytic manganese, and the product even in its small way has found war uses of considerable importance. Meanwhile, the Knoxville plant of the Electro Manganese Corporation, the sole commercial producer, was expanded to about 4 tons per day to supply needed material for the war program. Other proposals for commercial plants have not been favorably received by the War Production Board. The Bureau reported on one such proposal by the American Alloys and Chemical Corporation. Practice at BouldeR City The present practice, as carried out at Boulder City, which is being described in more detail in a current paper by the Bureau staff at Boulder City, starts with a manganese dioxide ore containing about 20 per cent manganese. Currently this ore comes from the Three Kids deposit near Las Vegas. The steps for the production of electrolytic manganese, in general, are as follows: 1. The manganese in the ore is reduced to MnO. 2. The MnO is dissolved from the ore in spent electrolyte, which contains about 38 to 47 grams per liter of free sulphuric acid, 135 grams per liter of ammonium sulphate, and 10 to 12 grams per liter of Mn as sulphate. In the leaching step the manganese is built back up to 32 to 36 grams per liter of Mn as sulphate; the pH is adjusted to neutral by means of gaseous ammonia and passed through thickeners. 3. The electrolyte is purified by adding H2S, which precipitates the heavy metals. After filtering, ferrous sulphate is added to the solution and oxidized with air and the solution is filtered and clarified on a precoat filter. 4. The purified catholyte is electrolyzed in a diaphragm cell using stainless-steel cathodes and lead-silver anodes. The current density is about 45 amp. per sq. ft. Current efficiencies of 60 to 65 per cent are regularly obtained.

Jan 1, 1944

By William Fink

MANY investigators have attempted to determine the true nature of the internal changes taking place during aging. Merica, Waltenberg and Scott1 were the first to propose a theory of age-hardening. They attributed the age-hardening of duralumin to the precipitation of minute particles of the compound CuA12. Later Zay Jeffries and R. S. Archer2 augmented the above theory by suggesting that the small CuA12 particles acted as "keys" causing "slip interference." Many other investi-gators3 have devoted much time to the mechanism of age-hardening, some corroborating the "precipitation" and "slip interference" theory, others coming to different conclusions because of effects that to them seemed unexplainable by the early theories; e.g., the increase of electrical resistance upon aging, the fact that no change in lattice parameter could be detected during the early stages of aging even at elevated tempera-tures, and the fact that the density did not change as would be predicted. In 1932, Merica revised4 his earlier precipitation theory to take care of these presumably anomalous effects. This revised theory, the "knot" theory, assumes that substantial age-hardening occurs before actual precipitation of solute as discrete particles. The assumed mechanism is one of diffusion of solute atones into groups forming distorted regions which act as "hard" spots and cause slip interference. These "knots" are assumed to have approximately the same lattice arrangement as the solvent.

Jan 1, 1936

By Å. Sterten, R. Tunold, J. Brun, K. Dalatun

c axis compression behavior of beryllium single crystals at three purity levels under hydrostatic pressures up to 27 kbars was determined. Extensive non-basal slip, observed by two-surface trace analysis and transmission electron microscopy, occurred under a hydrostatic pressure of about 12 kbars (175 ksi) for the high-purity (twelve-zone pass) material and at about 19 kbar (275 ksi) for the lower-purity (zone-leveled) material. Prismatic loops with a (c + a) Burgers vector were observed in association with second-phase parti- A principal factor limiting the use of beryllium is its brittle behavior when tested at the usual strain rates (E = 10-4 sec- 1) at temperatures below about 200°C and under impact conditions at temperatures in excess of 200°C. It has been proposed' that the brittle-ness of beryllium is associated with the lack of a sufficient number of independent slip modes and the absence of a slip mode with a Burgers vector out of the basal plane [presumably (c + a) pyramidal slip mode] and to the ease with which beryllium cleaves on the basal and second-order prism planes. The absence of pyramidal slip has been attributed to a high Peierls-Nabarro stress associated with the motion of dislocations with a (c + a) vector and the ease with which cleavage occurs on the basal and second-order prism planes. The experimental evidence in support of the proposed explanation for the brittleness of beryllium is far from complete; for example, that the ductile-to-brittle transition in polycrystalline beryllium is associated with the operation of profuse (C + a) slip has not been unequivocally established. The occurrence of (c + a) slip ({1122}(1123)) has been experimentally established2-5 under conditions where basal and prism cleavage are restricted in a c axis compression test. In these investigations (C +a) slip was found in high-purity beryllium single crystals tested in c axis compression* at 200°C and in Be-4.4 pct Cu and Be-5.2 pct cles in the lower-purity materials tested. The loops were related to surface "extrusions" observed on many of these same specimens. Nonbasal dislocations operating on (1122) planes with a (c + a) Burgers vector were observed. The presence of c and a dislocations together with (c + a) dislocations suggests that the (c + a) dislocations dissociate presumably on unloading or after failure of the test crystals to c and a dislocations. terial, (c + a) slip has only been observed near the the fracture4 surface in room-temperature c axis compression tests. Fracture in these tests occurs without measurable plastic flow, as determined with a strain sensitivity of 10"6. Since it has been shown for many metals that the application of hydrostatic pressure suppresses fracture,?-' it was felt that studying the behavior of unalloyed beryllium single crystals stressed in c axis compression under a hydrostatic pressure would reveal whether (c + a) can occur if fracture was prevented, and that it might elucidate the role of (c + a) slip in the ductile to brittle transition. Evidence that (C + a) slip is associated with increased ductility in a high-pressure environment has been found in stress-strain tests on poly crystalline beryllium.10 The present paper describes a study on the influence of a hydrostatic pressure environment on the occurrence of (c + a) slip in beryllium single crystals. Material of two purity levels was tested in c axis compression over the pressure range ambient to about 27.5 kbars.* 1) MATERIAL PREPARATION AND CHARACTERIZATION Two lots of low-purity single-crystal beryllium were used. The first lot was "ingot secondary refined grade" and designated lot A. The second lot (lot B) was produced by a two floating zone pass zone-leveling operation in an argon-filled sealed quartz apparatus on a 1-in.-diam by 12-in.-long bar of Pechiney secondary refined-grade vacuum-cast and hot-extruded material. The high-purity material (lot C) was made by traversing twelve floating zone passes through a similar bar of Pechiney secondary refined-grade vacuum-cast and hot-extruded material. In a series of spark cutting and lapping procedures,11 single-. crystal specimens some 0.12 in. sq by 0.30 in. high were made with the sides Parallel to the first- and second-order prism planes and the basal plane within 3' of arc of the top and bottom surfaces of the specimen. Such an accurate orientation is necessary because of the large difference in resolved shear stress

Jan 1, 1970

By R. W. Kraft, L. D. Graham

The process of' spheroidization, or more properly coarsening, of Al-CuAl,eutectic alloy specimens with various initial microstructures was studied by quantitative metallographic and X-ray diffraction techniques. By measuring the rale at which specimens with a very fine dispersion of phases (produced by quenching molten droplets of the alloy in water) coarsened it uias determined that the rate-controlling mechanism for coarsening was diffusion, probably of aluminum in the aluminum-rich phase. The lamellae in specimens with a high degree of microstructural and cr-ystallog/uphic anisotropy (produced hy unidirectional solidification of ingots) thickened during heat treatment by recession of the CuAl, platelets from jaulted regzons, yet the specinlens retained a very high degree of. anisotropy after prolonged heat treatments at a temperature within 8°C of the eutectic temperature. In such specimens the crystallographic orientation relationship between the phases remained constant and no change in the crystallographic substructure occurred. Based on these observations a model was developed for the coarsening—or rate of' thicken-ing—oj- the lamellar structures which predicts that the rate of decrease of interface area is proportional to the square of lamellar interface area. Experiments with degenerate and very coarse lamellar microstruc -tures preduced by extremely slow unidirectional solidification) indicate that initial microstructure is a most important factor governing the final micro-structure after heat treatment. The particle size and shape of dispersed phases are important parameters affecting the properties of a wide variety of two-phase materials. As is well-known, varietythe dispersed-phase particles tend to coarsen at appropriately high temperatures because the interface energy of the system is reduced by the concomitant reduction in interface area. The phenomenon of

Jan 1, 1967

F. G. SMITH.-Probably someone will ask whether I discovered why the bottoms of the large shells broke out. I did not, as a result of this investigation. An experiment was made along the lines indicated in this paper, to determine whether abnormal grains greatly affected the physical properties of brass. Two ordinary test bars were annealed for 1/2 hr. at 750° C. and physical properties determined on one. The other was covered with indentations made with a peen hammer and then reannealed. for 5 hr. at 750° C. It was found in the tensile test to be made up of large grains 1/4 to 1/2 in. in diameter. The physical properties, however, differed from those of the first bar only as much as might be expected after a 5 hr. anneal under normal conditions. It appears then that the large grains produced in this manner do not ruin the physical qualities of the brass.

Jan 12, 1919