Search Documents

By Leo Brewer, Gerd M. Rosenblatt

Thermodynamic calculations predict the species vaporizing from metal-oxide mixtures when reliable free energy functions, enthalpies of formation, and dissociation energies are available for the possible gaseous and condensed oxide components. Calculations of the oxygen to metal ratio in the vapor phase compared with the oxygen to metal ratio in a liquid metal saturated with oxide impurity are presented The possibility of purifying metals contaminated with oxide by vacuum melting or by distillation is discussed. Kinetic considerations affecting rates are neglected. IN recent years extensive information has been obtained on the thermodynamic stability of gaseous oxides of metals due to a variety of new types of measurement. Perhaps the greatest amount of information has come from the application of mass spec-trometry to the study of high-temperature vapors.' In many instances oxides of quite unusual oxidation states are found to be important in the high-temperature vapors. At low temperatures the standard free energy change for a reaction as given by the equation ?F° = ?H° - T?S° is determined primarily by the AH" value. However, at higher temperatures where the value of T in the T?S° term is large, the entropy term becomes equal to or greater than the AH term. At low temperatures only reactions for which AH is negative or only slightly endothermic are of importance. This restricts the main equilibrium species largely to those with completed octets or those with the principle oxidation number of the element. At

Jan 1, 1962

By Raymond Mancha

THE purpose of the Coal Division's Committee on Ventilation is to cover one principal aspect of mine ventilation thoroughly each year, instead of attempting to touch upon several different subjects. The Committee for 1943 consists of four members besides the Chairman. Members, selected because of both knowledge of the current topic of mine ventilation, and diversity of occupation, are: Carel Robinson, consulting engineer with an operating background; T. G. Fear, chief engineer for the Hanna Coal Co., an operator of varied experience in mine ventilation; E. H. Denny, chief of the coal mine inspection division of the U. S. Bureau of Mines, obviously well qualified; and C. M. Smith, editor of Mechanization with a background of mine ventilation study as a member of the mining department of the University of Illinois, at present retained as a ventilation consultant by the Climax. Molybdenum Co. of Climax, Colo.

Jan 1, 1944

By P. W. Gilles, B. D. Pollock

THE pioneering work of Steinitz1 and Steinitz, Binder, and Moskowitz2 has shown conclusively the existence at high temperature of two additional phases in the molybdenum-boron system and thus brings to a total of six the number of structures appearing in this system. To the structures Mo2B, MOB, and Mo2B5 they have added MO3B2, a new -MOB form, and have shown that MOB,, which has the same range of composition as Mo2B5, is only a high temperature structure of the latter. This solid solution, interestingly enough, includes neither of the compositions corresponding to the stoichiomet-ric compounds, MOB, or Mo2B5, but rather at all temperatures has intermediate values of composition. These workers have also, in the course of their work, measured melting points, transition temperatures, eutectic and peritectic points in the system and have shown that Mo3B2, because of its dispro-portionation at low temperature to Mo2B and MOB, is stable only in a limited high temperature range. During the course of the present work on the vaporization properties of the molybdenum-boron compounds, a few transition temperatures were observed. When the report of the other workers appeared, it was decided to repeat, in part, their study of the system. As a result, considerable evidence has been obtained that substantiates the specific kinds of melting processes they report as well as the general features of their diagram. However, a marked difference was found between the temperatures they report and the ones observed in this study, with the latter being higher. The purposes of this paper are to present the evidence obtained in this laboratory that verifies their diagram of the system, to give some important temperatures in the system, to compare them with those previously published, and to seek an explanation of the difference. Samples The metal starting material was 400 mesh molybdenum powder with a purity stated by the manufacturer to be 99.9 pct. The initial treatment, designed to remove volatile contamination, consisted of heating in a vacuum for 10 min to a temperature of from 800" to 1000°C during which a loss of 0.3 to 0.4 pct occurred. An assay following this treatment showed it to be 99.4 pct pure, with the principal impurity probably being oxygen. The boron starting material was obtained from the Cooper Metallurgical Laboratories and the Fair-mount Chemical Co. as 325 mesh powder with manufacturers' analyses of 99 pct or better. Initial treatment consisted of heating in molybdenum in a vacuum at about 1700°C for 10 min. During this time a loss of 3.5 pct occurred. An assay following this treatment showed the different samples to have purities ranging from 95.5 to 99.0 pct with iron and carbon as the principal impurities. Following the initial treatment, the elements were combined to form stocks of Mo2B and MOB by heating pressed mixtures in a vacuum to 1100" to 1200°C to accomplish reaction and to 1500" to 1900°C for a few minutes to evaporate the more volatile impurities. Analysis of the two compounds for boron by a modification of the method of Blumenthal3 and for molybdenum by the lead-molybdate method indicated them to have purities greater than 99 pct. The individual samples to be studied had compositions in the Mo2B-MOB range and consisted of mixtures of the stock compounds. Procedure As is usually the case in high temperature work the selection of containers for the samples posed some problems. For vapor pressure studies tantalum crucibles, allowing little contact with the pressed samples, were used and some of the observations made during these experiments are pertinent to the study of the phase diagram. Most of the experiments, however, were performed in graphite containers, as were those of the previous authors. Two kinds of spectroscopic grade graphite crucibles were used. One was a % in. cylinder, 3/4 in. high, containing seven 3/16 in. holes drilled 1/2 in. deep into which were packed samples of the different mixtures weighing 250 to 500 milligrams. The other, consisting of separate crucibles, was prepared by drilling 3/16 in. holes, 1/2 in. deep into 1/4 in. graphite rods % in. long. The 7/8 in. cylinder was heated directly by induction while the small crucibles were packed in a tantalum heating element for induction heating. All heating was done in a high vacuum system in which the pressure was generally less than 1x10-5mm and never rose above 2x10-5mm when the samples were hot. The general pattern of the heating in graphite was to heat rapidly to a temperature somewhat below the desired one, then to raise the temperature slowly. The samples were held for 2 to 5 min at the maximum temperature, which in all cases was far higher than that needed to produce reaction. The short time was employed to reduce possible contamination by the crucible material and to reduce composition changes that would occur because of vaporization. After examination following the heating, the samples were reheated to a higher temperature. Temperatures were measured with a Leeds and Northrup disappearing filament optical pyrometer, certified by the National Bureau of Standards, by sighting through a window at the top of the vacuum

Jan 1, 1954

By R. Taggart, D. H. Polonis, J. C. McMillan

Thin foil electron microscopy techniques have been used to study the micros tructure of a Ti- 7.5 wt pct vanadium alloy in the quenched and aged cond_itions. Selected area diffraction has identified a (1011) twinning mode accompanying the martens ite t9.an.sfo?rn~ation. Precipitation of the 0 phase during the aging of quenched alloys has been obsevced to occuv in the form of plates and needles with preferential growth along the (1120) direction in the a' matrix. In the present work, the micro structures of quenched and aged alloys of the 0 isomorphous Ti-V system have been investigated by means of thin-foil electron-microscopy techniques. Most of the previous studies of martensitic phases in titanium-base alloys have utilized optical microscopy and X-ray diffraction techniques. The application of transmission electron microscopy is more recent, and only a few such studies have been reported.1-5 This paper is concerned particularly with the crystallographic nature of substructures formed in the martensitic a' plates. The early stages of aging or tempering have also been examined to determine the modes of precipitation from the martensitic solid solutions. Such information is essential in studying strengthening mechanisms and in determining the feasibility of high-strength rnartensitic alloys based on titanium. Liu and Margolin6 reported several types of substructures within the martensitic plates of quenched Ti-Mn alloys. It was later suggested by Liu7 that the structure of martensitic plates might be very complex and not single crystals as normally assumed. The sub-markings could not be identified with the two possible habit-plane orientations {334}ß and {344}ß, and it was not positively determined whether they are associated with mechanical twinning. The recent studies by Armitage5 on titanium martensites in a variety of commercial alloys have indicated that twinning does not generally accompany the transformation. This observation is in accordance with the Mackenzie and Bowles model for the transformation in pure titanium8 which suggests that twinning is not to be expected. However, a number of other recent investigators have reported twinlike substructures in the martensitic plates of several titanium systems including commercia1 titanium,2,3 Ti-Cu,5,9 Ti-Ta,1 and the commercial alloy Ti-8A1-1Mo-1V. Blackburn* has reported that the structure of quenched Ti-8A1-1Mo-1V depends on the prior solution temperature. He identified two types of martensitic structures, one of which is described as a heavily faulted hcp or twinned fcc structure and the other an hcp structure with a high internal dislocation density. The latter type exhibited some twinning with a (1011) twin plane. EXPERIMENTAL PROCEDURES AND RESULTS The alloy used in the present work was a 7.5 wt pct V alloy that was prepared by conventional arc-melting techniques. This alloy composition was selected

Jan 1, 1968

By Roshan B. Bhappu, Ronald J. Roman, Dexter H. Reynolds

The reaction between manganese dioxide and molybdenite in a water- sulfuric acid medium was studied at atmospheric pressure and from 25° to 103°C. Both solids are dissolved to give, as final products in solution, Mo(VI), S(VI), and Mn(II). Stoichiornetric relationshifis are most simply represented by the equation MoSz + YMnO2 + 15H+ - HMoO-4 + 2HSO-4 + 9Mn++ + 6H20 The rate of this reaction was found to be dependent on temperature, manganese sulfate concentration, acid concentration, and, in a complex way, the surface areas of both manganese dioxide and molybdenite. Both the total amount of manganese dioxide and tnolybdenite and the ratio of manganese dioxide to molybdenite played a part in determining the over-all rate of the reaction. The effect of acid concentration on the rate was also dependent on the ratio of manganese dioxide to molybdenite. SEVERAL reports in the literature describe reactions using manganese dioxide in water-sulfuric acid media as an oxidizing agent. Nearly all previous work describes interactions between an ion and manganese dioxide, such as the oxidation of ferrous to ferric iron,' or the interaction between a molecule in solution and manganese dioxide, such as the oxidation of toluene to benzaldehyde.2 Only a few references describe the use of solid manganese dioxide to oxidize another solid in sulfuric acid. One report3 states, "Manganese dioxide in dilute sulfuric acid solutions had no beneficial effect (in leaching copper from chalcopyrite), but in more concentrated acid solutions the rate of solution was about the same as that for permanganate." In 1902 a German patent4 described a process which used manganese dioxide in strong (50°Be') sulfuric acid for oxidizing chromite ores to soluble iron and chromium salts. The process consisted of mixing the sulfuric acid with the finely ground ore and manganese dioxide. The pulp was then heated to about 120°C and an electric current passed through it. The manganese dioxide apparently dissolved in the strong, hot acid solution, oxidized the iron and chromium and itself was reduced to manganese 11! then was oxidized at the anode back to manganese dioxide, and the cycle repeated. An extensive study5 of the kinetics of the oxidation of pyrite with manganese dioxide indicated that in dilute sulfuric acid solutions (about 0.1 N) and at elevated pressures the dissolution of the pyrite was brought about by air oxidation of the iron to ferrous sulfate, followed by manganese dioxide oxidation of the ferrous sulfate to ferric sulfate. The mechanism proposed by the authors involved the oxidation of the iron at the surface of the manganese dioxide. Also! the oxidation of sulfide sulfur to sulfate was credited to the oxygen in the air, not to the manganese dioxide. Since the metallurgical literature is lacking in information concerning the use of one solid to oxidize another solid. the current investigation was under-

Jan 1, 1965

By H. M. Otte

Certain choices for the shear elements of the inhomogeneous distortion in the phenomenological theory of martensite formation are examined for their agreement with crystallographic and X-ray data of iron alloys. The assumption that the shear elements must represent slip or twinning systems characteristic of bcc metals is found to covey all observations, even when a small uniform dilatation is taken into consideration. In bct martensite, (011) becomes a possible twinning or faulting plane, in addition to {112), and qualitatively similar X-ray line broadening is to be expected from both. The basic concept inherent in the current theoriesl-4 of the formation of martensite is that the interface between the parent (austenitic) and product (martensitic) phase is an invariant strain plane (i.e., one that is undistorted and unrotated). Experimental evidence that the interface is of such a nature is available in certain transformations2'5'6 but for the transformation in iron alloys direct observation has not proved enlightening. Internal strains resulting from the formation of the small martensite platelets within the parent austenite matrix7 make it difficult to produce the desired evidence. Indirect evidence, however, such as the continuity of scratches in passing from untrans-formed to a transformed region, strongly indicates that the habit plane in iron alloys is an invariant strain interface. The scatter in habit planes in a given specimen8 would suggest that internal stresses have a slight but definite influence. On the other hand, composition changes which affect the lattice parameter can alter the habit plane appreciably, and by an amount greater than the scatter.' The success of the theories depends on the choice made for the "inhomogeneous distortion" or "complementary shear'' in the analysis and also on the choice for the parameter 6 representing a small uniform dilatation. In the approach developed by Wechsler, Lieberman, and Read'," it is implicitly assumed that 6 is unity. In the case of iron alloys, all observations cannot be explained without varying either the inhomogeneous distortion or 6 . Bowles and Mackenzie3 considered only the effect of varying d. They found it difficult to reconcile the wide scatter of habit planes with the theory and were forced to the conclusion that it may also be necessary to consider variations or different choices of the inhomogeneous distortion. Wechsler and Read" considered a limited number of possible choices for the inhomogeneous distortion, but no variation in 6, though this could easily have been introduced if so desired. It is the purpose of the

Jan 1, 1961

By J. E. Coyne, L. E. Tanner, J. E. Boyd

In recent investigations of the isothermal transformations of the retained 0 phase in a titanium alloy having 13 pct V, 11 pct Cr, and 3 to 4 pct Al, there have been indications that the w transition phase is the initial decomposition product at temperatures below about 950°C (510 c).' This metastable phase, found in a number of titanium-base alloys rich in stabilizing elements and known to have an adverse effect on their ductility and toughness, is not easily observed by the usual experimental techniques. Since wis coherent with the /3 matrix,495 distinct interphase boundaries are not revealed metallographically. However, in some cases, an etching effect (i-e., a "mottled" /3 surface) poorly resolved by light microscopy has been found to correspond with the presence of w.6 X-ray diffraction examination has generally been the most suc- cessful means for identifying this phase and crys-tallographic determinations have been made.4'5 Dynamic elastic modulus7 and electrical resistivity measurementse have also aided in the identification of w. In the current study, the electron microscope was utilized to examine microstructures in aged Ti-13V-11Cr-3A1 that were unresolvable by light microscopy techniques. Using negative parlodion replicas (shadowed with chromium at 27 1/2 deg) examination was made of various transformation

Jan 1, 1962

By A. Satter, J. M. Campbell

Reported herein are the results of a careful and detailed study of the non-ideal behavior of pure gases and their mixtures. Included are: (1) new data on five ternary systems composed of methane, ethane and H2 S; (2) a simple compressibility factor correlation that is inherently superior to present correlations, particularly for gases containing H2S and CO2; and(3) a detailed study of combination rules and the effect of system composition on the choice thereof. This study makes use of the rather large mass of data already available in the literature. A complete re-examination of the data and ideas presented in the last 25 years was considered desirable as a prelude to our basic concern — the effect of diluents on gas behavior. A consideration of both the macroscopic and microscopic properties of gases provides a better insight which, in turn, gives a firmer basis for improved correlation techniques. Such a study has shown that expressing the compressibility factor Z as a function of acentric factor w, as well as reduced temperature and pressure, yields a correlation that is broader in scope. The study of various combination rules has shown that better results are obtained by "tailoring" the rule used to the system composition. To do so improves the basic reality of results by overcoming some of the anomalies often found when using Kay's rule alone. Tentative recommendations are made regarding the most reliable combination rule for use with a given class of gas. The data presented are useful for estimating the direction and magnitude of the expected deviation when using a given rule. Although more work is needed, particularly around the critical region and with CO2 mixtures, the advantage of the classification scheme proposed is apparent. INTRODUCTION When one attempts to write a PVT equation to fit the data for actual gases, greater precision is obtained by the use of a multiple number of empirical constants. This has lead to multiple-constant equations such as Benedict-Webb-Rubin, Beattie-Bridgman, Keyes, etc., which are capable of yielding very precise results for pure gases in a range for which data to get the constants are available. As a matter of practicality, though, the use of such equations for gas mixtures is limited. Because of the infinite number of gas analyses available, any attempt to compile the constants needed requires a prohibitive amount of experimental data. This could be overcome by the use of a combination rule, but there is no real advantage in doing so because the end result offers no practical impovement over the Z factor correlation. The most widely used method of predicting the volumetric properties of pure gases is based upon the "theorem of corresponding states". According to this theorem, "all pure substances have corresponding molal volume at corresponding temperature and pressure if the reference point of correspondence is the critical point". Generalized compressibility charts for gases were prepared first by Cope and associates1 in 1931 and later by Brown and co-workers2 in 1932. However, the most commonly used charts are those of Dodge,3 Nelson and Obert,4 Hougen and atsson: and Standing and Katz.6 The work of Katz and co-workers has provided us with basic data for the hydrocarbons most widely used today. Their original chart6 was compared with a relatively large amount of multi-component data for gases consisting almost entirely of normal paraffin hydrocarbons. A deviation of only + 1.2 per cent was obtained.39 In the 20 years following publication of this work it has been found that the behavior of most mixtures of paraffin hydrocarbons could be predicted by this correlation within at least 5 per cent. Where difficulty has been encountered it has largely involved one or more of the following circumstances: pressures above 4,000 psig, mixtures containing large amounts of heavy ends and/or aromatics, systems in the critical region and mixtures containing polar compounds and/or CO2. The abnormal error sometimes found with such gases, not too unexpected for this method, is

By H. R. Hanley

IT is a well-known fact that the solubility of zinc compounds decreases when these compounds are roasted in contact with iron compounds, but descriptions of tests to quantitatively express the fact have not appeared in the literature. Possibly such an expression cannot be uniformly and exactly duplicated by different operators because of the variation in the personal equation. In a general way, however, the reactions between zinc compounds and iron compounds under roasting conditions will show a certain trend with changing conditions and the approximate quantitative expression of this trend appears reasonably well established by experimental work conducted for this purpose. Ferrites and Marmatites The name "ferrite" has been given to the compound of zinc and iron which has the formula Zn0.Fe203. Among the questions pertinent to this subject are those involving inherent or natural ferrite, and also the synthetic or artificial variety. The inherent or natural product is formed when the mineral containing iron and zinc sulfides isomorphously crystallized is subjected to oxidation at roasting temperature. These isomorphously crystallized minerals are known, mineralogically, as marmatites, and contain ZnS and FeS in ratios of 2 to 1 up to 5 to 1 respectively. The zinc and iron sulfides form a definite mineral. They are firmly attached to each other and form common contact planes through which diffusion of the entities occurs during the roasting process. This diffusion of the molecularly intimate entities produces, during roasting, the compound referred to as ferrite, in proportion to the amount of iron originally present in the marmatite. For example, a marmatite from British Columbia containing 9.739 per cent. Fe and 56.87 per cent. Zn corresponds with the mineral having the formula 5ZnS.FeS. The ferrite produced in roasting, which has the formula ZnO.Fe203, contains 27.07 per cent. Zn and 46.40

Jan 1, 1929

By J. J. Kramer, K. Foster

The orientation distribution of surface-energy -induced secondary recrystallized grains was determined. This work was conducted on thin sheets of a 3 pct Si-Fe alloy annealed under environmental conditions that furor grouth of grains with a (100) plane in the surface of the sheet. The texture was found to be extremely sharp and almost independent of sheet thickness. The distribution varied exponentially with the angular deviation from the {100} plane. It was possible to relate the distribution to the nu-cleation rate of the secondary rains as influenced by the surface-energy difference. THE role of surface energy in the secondary grain growth of cube-oriented grains (grains with a (100) plane in the plane of the sheet) in thin Si-Fe sheets has been previously discussed.1-4 In high-purity sheet material normal grain growth usually occurs until the grains have extended through the sheet. Further grain growth is inhibited by the thermal grooving of the boundaries at the sheet surface. However, additional growth of cube grains can occur by a secondary grain growth process under conditions where the (100) plane has a lower surface energy than other orientations. Apparently for these alloys, cusps exist in the polar plot5 of surface free energy with the lowest cusp energy occurring at the (100) orientations. This has been reported to be the result of preferential adsorption of sulfur on the (100) planes.6 As a result of this process, a distribution of orientations could arise from two possible mechanisms. First, when a cusp is present in the polar plot of surface free energy, there are orientations inside the cusp that have a lower surface energy than elsewhere on the polar plot. Also, at sufficiently high temperatures, flat surfaces whose orientations are inside or just outside the cusp (depending on its shape) can often thermally etch, yielding a microscopically stepped surface of even lower surface energy. As a result, grains oriented close to cube would also have a lower surface free energy, either because of the cusp shape or by thermal etching, and could possibly grow as secondary grains by the surface-energy phenomenon. One should thus observe a distribution in the surface orientation of the cube grains comprising the secondary structure. It is the purpose of this paper to investigate this orientation distribution experimentally and to discuss the factors involved in its formation. For this purpose, the surface orientations of a large number of secondary grains in various sheet thickness were determined by means of the Laue back-reflection X-ray technique. PROCEDURE A vacuum-melted 3 pct Si-Fe alloy containing a nominal impurity content of 0.005 wt pct was processed into strip. A single cold-rolling step of 90 pct reduction was used for each strip regardless of the final sheet thickness. Final strip thicknesses of 0.60, 0.30, 0.15, and 0.075 mm were used. Care was taken to insure that the final strip surface was smooth and flat. All strips of a given thickness were annealed together at 1200°C in dry hydrogen (dew point -70°C) to develop the desired secondary structure and to insure identical environmental annealing conditions. The annealing time was selected to develop a complete secondary structure in the thinner sheets but to permit the thicker sheets (0.60 mm) to have residual primary grains remaining. This was necessary to determine whether growth impingement could lead to one secondary grain consuming another at a greater angular deviation. For the X-ray determination of the surface orientation of the secondary grains, a special specimen holder was used. The camera and holder arrangement could be aligned by X-raying a grain in three positions rotated 180 deg to each other. Thus, with a small beam X-ray focus (1 mm), the surface orientation of any grain could be determined to within one-half a degree. The surface orientations of one hundred cube secondary grains were determined for each sheet thickness. The criteria of a secondary grain were its size relative to the sheet thickness and the number of sides of the grain observed in the sheet surface. (A primary recrystallized grain extending through a sheet will generally have six edges visible in the plane of the sheet, whereas a secondary grain will have many more when growing entirely into primary grains.) Grains were selected as randomly as possible by X-raying every secondary grain found along a line drawn on the strip. No attempt was made to determine the exact orientation of the planes of the surface, as many strips from randomly selected sheets were used. On1y the angular deviation of the surface plane from {100} was measured. In order to assess the volume distribution in the

Jan 1, 1965

By Irwin Remson

Some unique hydrogeologic issues are inherent in the problems of siting, designing and licensing a mined geologic high-level nuclear waste repository. The problems involve hydrogeologically unfamiliar rocks for which little proven technology has been developed, long containment periods, elevated temperatures, and externally-imposed management constraints. In evaluating the existing national program, it should be recognized that hydrogeology is only one aspect of the total nuclear waste disposal problem, that the use of multiple barriers requires that the hydrogeologic system be considered in its entirety as a total system, and that engineering modifications can improve the isolation capabilities of certain barriers. Important research questions involve the mechanics of transport through dense fractured and unfractured rocks, methods for measuring vertical hydraulic conductivity, and a variety of geochemical questions. Current expectations for "high quality data" from either in situ or laboratory testing are unrealistic, and a modified approach to repository hydrogeology is needed. The dilemma is that the hydrogeological characteristics that make a potential host rock more satisfactory for respository siting are the same characteristics that are difficult to characterize and make the particular site more difficult to license. Finally, evaluation of the containment potential of any candidate site will become meaningful only with detailed underground exploration, mapping and testing in the host rock formations at the repository levels.

Jan 1, 1984

NEW MEMBERS The following list comprises the names of those persons who became members during the month of December, 1913: Members ADAMS, CHARLES W., JR., Smelting, American Smelting & Refining Co., Murray, Utah. ARMSTRONG, FRANK H., Mechanical Engineer Vulcan, Mich. ARNOLD, JOHN B., Attorney-at-Law Room 840,200 5th Ave., New York, N. Y. BOYS, HARRY R., Mining Paso Robles, Cal. CAVANAGH, JOHN L., Min. Engr., Nova Scotia Steel & Coal Co.; Wabana, Newfoundland. CHOW, KAI CHI, Student 1120 Amsterdam Ave., New York, N. Y. CLARK, ARTHUR B., Mining Engineer 72 Harbour Bldg., Butte, Mont. CURLEY, JOHN R., State Mine Inspector P. 0. Box 633, Leadville, Colo. DAVIS, ANGUS W., Mining Engineer, Consolidated Mining & Smelting Company of Canada, Trail, B. C., Canada.

Jan 1, 1914

By G. S. Tint, M. Herman, V. V. Damiano

Dislocation arrays and substructures were studied in cadmium doped zinc crystals using a newly devised etching technique. Cadmium precipitates delineating the dislocations were revealed by etching a surface closely parallel to the (0001) slip plane. Cinephotomicrography of the continuous etching process revealed the three-dimensional aspects of dislocations in the bulk crystal. Dislocation etch patterns were studied in both deformed and annealed crystals after suitable aging at room temperature. The effect of annealing was evidenced by a rearrangement of the dislocations into low-angle boundaries and hexagonal networks. ETCH pit techniques have been used extensively to study dislocations in both deformed and annealed bulk metal crystals. Ideally one hopes to obtain a one-to-one correspondence between the etch pits and the points of emergence of the dislocations at the surface. One then attempts to deduce the way in which dislocations are arranged in the bulk crystal from the arrangement of etch pits on the surface. It is clear that one can obtain only limited information of the dislocation configurations inside the crystal from etch pit studies of single surfaces. Considerably more information is obtained if one is able to follow the course of the dislocations through the crystal using progressive etching technique. Techniques of this sort were used by Gilmanl to study dislocations on the slip planes of NaCl crystals and by Damiano and Tint2 to study dislocation arrangement in zinc crystals grown from the melt. The present paper makes use of a technique first described by Tint and Damiano3 to observe and continuously record the dislocation structures which appear while a crystal surface was being progressively etched. Studies were made on cleaved (0001) surfaces to reveal the dislocations along their length on the surface closely parallel to the slip plane. The technique for revealing segments of dislocations along their length by etching is well known. Wilsdorf and Kuhlmann-wilsdorf4 revealed disloca- tions along their length in aluminum containing a few percent copper, when precipitates segregated along the dislocations. The technique was used by Low and Guard5 to study dislocation configurations on the slip plane in Fe-Si alloys containing carbon. In the present work the technique was applied to zinc containing cadmium since it was shown by Gil-man6 that a cadmium-rich phase could be made to precipitate from supersaturated solutions along dislocations in zinc. Segments of dislocations delineated by the precipitates were revealed by etching a surface prepared by cleaving the crystal. The three-dimensional nature of dislocations and substructures was thus studied from the cinephotomicro-graphic record of the continuous etching process. EXPERIMENTAL Single crystals of zinc containing the order of 0.1 pct Cd were prepared by slowly lowering a graphite crucible containing the melt through a temperature gradient of 15°C per cm at a rate of 1.5 X 10-3 cm per sec. "As grown" crystals were aged for periods of 1 month at room temperature, then cleaved in liquid nitrogen, and etched according to the procedure used by Gilman.' The etchant containing 32 g of CrO3, 6 g of hydrated Na2SO3 in 100 ml of water behaved as a chemical polish for zinc and etch pits were produced at the site of precipitates or inclusions. After the precipitates or inclusions were removed from the surface, the etch pits left behind were eventually polished smooth. This behavior enabled one to continuously observe the surface while the specimen was immersed in the etchant. Best results were obtained when the specimen surface was vertical and the reaction products of polishing were continuously removed by gravitational convection. Some crystals were heavily deformed in excess of 25 pct strain, others were lightly deformed the order of a few pct by compression such that the deformation occurred essentially by basal glide. Some crystals were etched immediately after deformation, others were allowed to age at room temperature for several weeks prior to etching. Heavily deformed crystals were annealed at various temperatures and etched on the cleavage plane immediately after annealing, others were allowed to age at room temperature for several weeks prior to etching. The etched structures of deformed and annealed structures were studied. Similar experiments were conducted on 99.9999 pct pure zone refined Tadanac zinc crystals which

Jan 1, 1963

By Joseph Gurland

EVERAL carbide-cobalt compositions were pre-^-5 pared for the purpose of determining the transverse rupture strength of various carbide-binder systems. The binder content was held at 10 and 37 volume pct Co, so as to be representative of low and high bjnder compositions. The carbides used, WC, Tic, TaC, CbC, VC and ZrC, were selected on the basis of availability, knowledge of their properties, and small solid solubilities in the binder metal at room temperature. The methods of preparation and carbon analysis of the carbides are summarized in Table I. The carbides with cobalt added were ball milled, pressed, and sintered. vacuum sintering was used throughout, except for the WC-Cs alloys, which were sintered in hydrogen. The sintering temperatures ranged from 2500" to 2750°F for the low binder alloys and from 2300" to 2550°F for the high binder alloys. Compositions and properties of the sintered com- pacts are presented in Table 11. For the transverse rupture strength, the average and range of the five best samples of each alloy are listed. Discrepancies between the actual and theoretical densities are attributed to carbon deficiencies in some samples. The theoretical densities were calculated by assuming mixtures of carbides of stoichiometric compositions and cobalt. Representative microstructures are shown in Figs. 1 to 6. The porosity was A-2 or better' in all alloys except those with ZrC. A grain size of about 3 p was

Jan 1, 1958

By AIME AIME

As already announced in the January Bulletin, this publication will be issued during the coming year monthly instead of bi-monthly as heretofore. Among other reasons for this change, it is desired to effect thereby the earlier transmission to members of important papers, lists of candidates for membership, and other items of timely information. Spokane Meeting and Excursions. Further details of the 97th meeting of the Institute have been sent to members in the Circular of May 8, 1909. The list of those intending to go on the excursion is filling up, and since preference in position of state-room or berth is given in the order of application, members and guests who expect to accompany the party and have not yet communicated with Mr.. Theodore Dwight, 29 West 39th St., New York, N. Y., are earnestly requested to do so without delay. For convenience of the members a summary of the additional information is here presented. A special train of Pullman cars will leave Chicago about September 15. This train will be side-tracked at all places visited, and the sleepers will be available for lodging and the dining-car for meals during the entire trip, except during the Yellowstone Park tour. The general cost of the trip per member will be $300, which includes transportation, berth, and meals for the entire trip from Chicago back to Chicago, almost 6,000 miles, and the tour through. Yellowstone Park, occupying in all about 30 days. Special, accommodations on the train will be furnished at the following rates

Jun 1, 1909

Jan 1, 1925

By Mark J. Klein

An internal-friction profile induced by nitrogen in Cr-35 at. pet Re was studied as a function of nitrogen concentration and heat treatment. From these studies, the solubility of nitrogen in this alloy was deduced. The equilibrium solubility of nitrogen in chromium does not appear to be substantially changed by the addition of 35 at. pet Re to chromium. However the precipitation kinetics of nitrogen from solution are significantly decreased. IT has been found that rhenium has a beneficial effect on the low-temperature ductility of Group VI-A metals. As part of a study to investigate the mechanism of this increased ductility, it was of interest to compare the concentration of interstitials retained in solution in one of these ductile bee alloys with the concentration retained in solution in its base metal. In this regard, a study of the solubility of nitrogen in ductile Cr-35 at. pet Re was selected for this phase of the investigation because the solubility of nitrogen in the base metal, chromium, has been determined over a fairly large temperature span.1-3 In addition, nitrogen is known to have an embrittling effect on chromium,4 but does not appear to have a comparable embrittling effect on Cr-35 at. pet Re.5 The experimental method selected for this study was the measurement of internal friction. This technique allows interstitial-concentration measurements to be made in bee metals that are sensitive to small changes in the concentration of a particular interstitial, even when other interstitials are present. When subjected to a cyclic stress, interstitial atoms in solid solution give rise to an internal-friction peak whose origin is the stress-induced ordering of interstitials into preferred lat- tice sites. These internal-friction peaks signify a dissipation of elastic energy which is greatest when the period of oscillation is comparable with the relaxation time for the attainment of an equilibrium interstitial distribution. For dilute interstitial binary alloys, the height of the internal-friction peak is proportional to the concentration of interstitial atoms in solid solutions. snoek8 has shown that the internal friction, Q-1, may be expressed by the equation where A is the relaxation strength, ? is the angular frequency, and 7 is the relaxation time. The relaxation strength, A, is proportional to the concentration of interstitials taking part in the relaxation if no interaction occurs between solute atoms. Thus values of peak height, which can be determined as a function of temperature, give a measure of the relative concentration of interstitial atoms in solution at various temperatures. If equilibrium has been attained, the peak heights will be proportional to the interstitial solubilities. The constant that relates A to the interstitial concentration can be determined experimentally from peak-height measurements as a function of concentration for specimens of constant crystallographic orientation. When this has been done, Q-1 measurements can be used to determine solubilities according to the equation C - KQ-1 where C is the soluble interstitial concentration and K is a constant that can be experimentally determined. It is possible, however, that lattice imperfections may bind interstitials to certain lattice sites. Internal friction does not measure these interstitial~, but does measure interstitials which are free to move in the normal lattice sites when subjected to an applied oscillating stress. On alloying the pure metal with a substitutional

Jan 1, 1965

By W. C. Ellis

IN an ingot of germanium solidified progressively from the bottom by a method' devised by J. H. Scaff and H. C. Theuerer, examination discloses ex- IH. C. Torrey and C. A. Whitmer, Crystal Rectifiers. p. 364. 1948. New York. McGraw-Hill Pub. Co. tensive twin relationships. A slice taken about midway in a cylindrical ingot approximately 3/4 in. in diameter and 1 1/2 in. in length, after etching and polishing to delineate different orientations, is shown in fig. la. The orientations of the regions designated with letters were determined by Laue X-ray back-reflection methods and plotted on stereograms. The orientation relationships of the designated components were determined by comparing the values for the nine angles between the three respective cube poles of each orientation with the values calculated in a formal treatment of octahedral multiple twinning in cubic crystals. Germanium, diamond cubic in structure, has the octahedral twinning habit. I am indebted to K. H. Storks for the calculation of the angular relationships of cube poles in octahedral twinning to four orders. The set of values for the nine angles is distinctive of the order of twinning. Confirmation for a multiple twin relationship is obtained from the determined indices of the mirror planes. These exist for all orders of twinning through the third and for some of the fourth." If the orientations are not those for twinning, then the nine angles for the cube poles do not correspond in value and distribution to those formally calculated. Since all nine angles must correspond in values and distribution of values to the calculated ones, the Laue method with a precision of one or two degrees is adequate to establish or deny with confidence the existence of multiple twins. Regions of the same orientation can also frequently be identified by the optical reflections. For example, the narrow twin bands in A at 2: 00 o'clock have orientation B1. The interesting twin relationships shown schematically in fig. lb were found for the section in fig. la. Most of this slice was made up of orientation, A, appearing in widely separated regions. Of the four possible first order twins of A, three were present in this slice and are designated by B with subscripts. Four second order twins of A are designated by C with subscripts. It is worth emphasizing that two of these, C, and C,, are second orders of A through the first order missing in this section. Two regions, designated by D with subscripts are third order twins of A. D2 is a sixth order twin of D,. All orientations found were ascribable to multiple twinning, as if the orientations in this section originated earlier in solidification from a single nucleus. The presence of extensive multiple twinning to- gether with the absence of other orientations appears to be a characteristic result in many instances of solidification of germanium. Fertile conditions for twinning probably exist in the array of atoms in the diamond cubic structure. The high order twins in the section shown, it is reasonable to presume, are the result of progressive octahedral twinning through several generations in the material freezing earlier. Some of these generations do not appear in this section, it is suggested, because their orientations with respect to the growth direction were unfavorable for survival. The extensive twinning is probably promoted during solidification by constraint imposed by volume increase, and to an irregular growth front. Twinning may also be due, in part, to the attempt of the solidifying region to attain the orientation most favorable to the growth direction (maximum thermal gradient). The nucleus for a twinned orientation could have its origin in a "stacking fault" on the close-packed octahedral plane. Further work is being done in which the course of twinning throughout an ingot is being studied. The results appear to be important in the general theory of solidification.

Jan 1, 1951

By John T. Norton, Matthew J. Donachie

Residual lattice strai?zs were produced in 2024 aluminum and ingot iron by uniaxial tensile deformation. These strains were rneasured on the original surface and ulith depth below the surface. The strains conformed approximately to those from a macroscopic stress distribution but they were not truly macroscopic in nature. The exact mechanism which apparently causes the coherently difi9,acting region of each grain to behave as if macroscopically stressed was not determined. MACROSCOPIC stresses in metals produce strains in the lattice which result in X-ray line broadening and line displacements. The latter effect can be utilized in a technique for determining stresses in metals as first shown by Lester and born.' Subsequent advances in technique have enabled the X-ray method of stress measurement to be satisfactorily applied to many problems involving residual stresses of a macroscopic nature, such as those due to welding, grinding, shot-peening, and so forth. In the case of stresses such as those described above, the correlation of X-ray- and mechanically determined data has been generally good. However, plastically extended polycrystalline metals have sometimes been reported2 to show line displacements upon release of the applied tensile load, yet the nature or origin of the residual lattice strains, rls, producing these displacements has never been clear. As will be pointed out, this lack of clarity regarding the macroscopic or microscopic nature and origin of these stresses casts doubt on the validity of results achieved by the commonly accepted techniques of X-ray stress measurement. This anomalous behavior requires clarification to remove the doubts concerning X-ray stress measurement. The present paper is the result of an investigation of the interesting behavior of such plastically extended polycrystalline metal bodies. The studies were originated to carry out the following tasks: 1) Observe whether a residual lattice strain is produced as a result of plastic extension and show whether any residual lattice strains produced can be related to the usual concept of a macrostress. 2) Examine the origin of any residual lattice strains observed. 3) Consider the implications or consequences of the existence of such residual lattice strains on the problem of X-ray stress measurement. THEORY 1) Lattice Strains. The theoretical developments necessary for the treatment of lattice strains and their relation to stresses follow from the classical theory of elasticity and have been adequately covered by arrett. For an isotropic solid under homogeneous deformation, it can be shown that, for uniaxial stresses where Dl is the macrostress acting in the longitudinal direction; E$L is the lattice strain in the plane defined by the surface normal and the longitudinal direction at an angle, , from the surface normal; ET is the similar strain in the transverse plane; E is Young's modulus; and v is Poisson's ratio. Eq. [2] is independent of angle + and Eq. [I] is a linear function of sin2, see Fig. 1, and can be solved analytically for DL if E and u are known and EL is measured. Thus, a uniaxial macrostress will be indicated by a linear E,L vs sinZ plot and a

Jan 1, 1962

Abramovits, Charles, Student, Case School of Applied Science Cleveland, Ohio. '37 Abreu, Ovidio M., Student, Stanford Univ Stanford University. Calif. '38 Adams, Albert, Student, New Mexico School of Mines Socorro, N. M. '38 Adams, Benjamin C., Jr Address Wanted. '36 Adams, George H 44S2 4th St., Riverside, Calif. '36 Adams, Robert E., Student, Univ. of Wisconsin Madison, Wis. '38 Adkisson, J. F., Jr., Student, Agricultural & Mech. College of Texas, Box 2044, College Station, Tex. '38 Afshar, Hodji khan A., Amiranian Oil Co 10 Khiahan-i-Nusrat, Teheran, Iran. '35 Agvas, Cesar G., Student, Adamson School of Industrial Chem. & EngrgManila, P. I. '38 Ahlen, Louis S., Student, Univ. of North Dakota Univ. Sta., Grand Forks, N. D. '37 Albers, Francis C., Student, Univ. of Wisconsin Madison, Wis. '38 Alden, George P., Student, Univ. of Tulsa Tulsa, Okla. '38 Alexander, Donald B... Student. Univ. of Oklahoma, Sigma Nu House Norman, Okla. '37Alexander, Joe M., Student, Agricultural & Mech. College of Texas. Box 954. College Station. Tex. '38

Jan 1, 1938