Search Documents

By D. E. Etter, J. E. Selle

The Pu-Ce phase diagram was determined by differential thermal analysis, metallography, and elechm-nricroprobe analysis. The dingram is chararterized by a eutectic with extensive solid solubility in the cubic Phases of both cerium and plutonium. No intermediate phases were found. Cerium is soluble in e plutonium to 16.0 at. pet Ce at 626OC nnd in d plcltoniurn to 23.0 at. pet at 613 "C, decreasing to 17.5 at. pet at room temperature. No solubility in the a, ß, or ? phases was jound, and the mininum cerium required to stabilize 5 plutonium to room temperature is 3.2 at. pet. The maximum solubility of plutonium in 6 cerium is 19.5 at. pet at 721OC, and the maximum soluhility of plutonium in ? cerium is 34.5 at. pet. Invariant points in the system are: a) eutectic at 626oC, L16.5 = E Pu16.0 + y Ce65.5; b) peritectoid at613oC, e Pu13.5 -y Ce65.5- d Pu23.0. AS part of a program aimed at the determination of the phase equilibria in the Pu-Ce-Cu ternary system, preliminary investigations were made of the three binary systems. A survey of the Pu-Ce binary system by differential therma1 analysis indi- cated several areas of disagreement with the published diagram,' primarily in the shape of the liquidus surface. Consequently, a thorough investigation of the system was undertaken, and this report presents the results of the study. EXPERIMENTAL PROCEDURE Three methods of investigation were used: differential thermal analysis (DTA), metallography, and analysis with electron-microprobe X-ray analyzer (EMX). The EMX analysis was particularly useful for the determination of solvus lines. The DTA method was most useful for the determination of the liquidus curves. Metallography complemented both of these techniques. Materials. The cerium metal used for most of this work had a freezing point of 805°C. This material showed 15°C premelting, and was found metallographically to contain some unidentified in~lusions.2 The temperature of premelting is defined as the point at which the DTA curve breaks away from the base line, analogous to a curve obtained from a solid-solution alloy. Several compositions were prepared near the cerium end of the diagram with higher-purity material which had a freezing point of 800°C. etallographic analysis showed this material to be relatively free of inclusions and only 8°C premelting was observed. Major impurities were found by spectrographic

Jan 1, 1964

By C. R. McEwen

The displacement equations of Buckley and Lever-ett' have been successfully applied to the prediction of oil recovery in frontal drives for a number of years. Commonly, the capillary pressure term is omitted from Leverett's fractional flow formula. The resulting satura-tion-vs-distance curves become multi-valued, however. Buckley and Leverett, recognizing that the neglect of capillarity was most likely the cause, proposed that this part of the solution he ignored. An ingenious method of propagating a discontinuity in place of the multi-valued portlon of the curve was devised by Cardwell using "non-capillary displacement theory". However, it would seem that a completc description of the displacement pracess would require the inclusion of capillary forces. Three publications on displacement theory have appeared in which capillary pressure was included. Ter-williger. et al', calculated saturation profiles which matched those which they observed when gas displaced water vertically downward. Based on their study, Jones-Parra and Calhoun5 roposed a method of computing saturation distributions sufficiently removed in time from the initial conditions so that all saturations in the flood front region were assumed to move with the same velocity. This latter assumption corresponds to the tangent construction on the flowing fraction-vs-satura-tion curve proposed by Welge." A numerical solution to the problem of water displacing oil from a water-wet porous medium was recently presented by Blair, ef at'. The initial conditions included a uniform saturation slightly above interstitial water saturation. that is, the permeability to water ahead of the front was not zero. This appeared to result in a region of slowly rising water saturation ahead of the front, at least for the particular set of relative permeability and capillary pressure data used to illustrate the computation. The authors also postulated an "end-effect" at the outflow face of the system, whereby no water could pass out of the system until the water saturation had built up to a high value. The saturation profiles computed under these assumptions show water accumulating at the downstream end of the system while the flood front proper is still traveling toward the outlet. The purpose of this paper is to present the results of a numerical solution to the one-dimensional water-flooding equation in which no outlet end-effect is considered and where there is no flow of water ahead of the flood front. It should be noted that the contemporary paper of Fayers and Sheldon8 deals with the problem under discussion. For a thorough treatment including both capillarity and gravity the reader is referred to their paper.

By George H. Found

DURING recent years considerable interest has been focused on the energy-absorption characteristics of metal when it is cyclically stressed in vibration. The most familiar manifestation of this phenomenon, which is called the "damping capacity" or "internal friction" of a material, is involved in the dissipation of mechanical energy of vibration, which otherwise would build up to stress levels where the problems of noise and fatigue are involved. In addition to its engineering importance in structures, the damping behavior of metals, particularly at low stress amplitudes, has also been used as a unique metallurgical research tool with which to provide sensitive means for indicating certain structural changes within metals. Important contributions toward understanding the energy-dissipating mechanisms that are responsible for internal friction in metals have been made in the last few years. The information is not yet sufficiently extensive, however, to provide a useful metallurgical concept describing exactly how the structure affects the internal friction, or to encourage more general use of this technique among metallurgists. Three fundamental mechanisms have been proposed, as a result of recent experimental investigations, to account for the internal friction in nonferrous metals in low-stress amplitude tests. These include damping due to internal thermal currents that are created and flow in metal because of differential vibratory stress effects,1 damping due to localized inelastic stress relaxation at inhomogeneities within the metal,2,3 and damping related to plastic flow of a localized type for which an explanation has been sought in terms of the dislocation theory.4 How each of these mechanisms functions as a result of structural changes in the metal is, in general, not well understood because of insufficient experimental data for which the controlling variables have been segregated and because of uncertainties in regard to the nature of the structural changes themselves. In several investigations the effects of cold-working on the internal friction of polycrystalline brass and aluminum have been described. As reported by Köster and Rosenthal,5 and by Förster and Breitfield,6 there is an initial large increase in the damping when the metal is worked. The initial high value is not stable, but declines rapidly, at first, in a hyperbolic manner. About 100 hr, after straining, a stable value is reached of magnitude proportional to the amount of strain.7 In Fig. I is shown the relationship found by Zener and his collaborators between the internal friction due to cold-working of alpha brass and the amount of cold-working.8 Several investigators have made internal-friction measurements on worked poly-

Jan 1, 1945

By R. T. Hukki, A. M. Gaudin

Previous work on the principles of comminution has shown: (I) that the surface produced is proportional to work input (Rittinger law,1a-3); (2) that there is regularity to the weight distribution of the fragments according to size.4-10 In this paper it is brought out that the surface on the fragments is distributed in definite and simple relation to size. The experimental work has involved: I. Construction of an apparatus capable of measuring the surface of mineral fragments independently of the chemical composition of the fragments and independently of the site of the surface; 2. Refining the methods available for measurement of particle size; 3. Designing and building a crusher capable of operating on very small quantities of mineral, if necessary on single crystals, and in such fashion as to minimize handling losses of material. Complete experiments have been carried out with massive quartz and individual quartz crystals. partial experiments, lacking surface measurements, have been made with glass spheres, galena, sphalerite, fluo-rite, salt and coal. Introduction The existence of regularity in weight distribution with size was noted many years ago, especially by A. 0. Gates;' the subject was also studied in detail by one of us.6 In the latter paper it was shown that rocks can be divided into two classes: homogeneous rocks, which show no preferential breaking, and heterogeneous rocks, which show preferential breaking at the grain size of the rock. It was shown, furthermore, that the fragments obtained by rupturing a homogeneous rock occur (in the fine range) in such abundance as to permit the writing of a relatively simple equation to relate the weight retained on a screen to the screen opening. With screens of which the openings are in constant ratio, the weight retained, w, is related to the screen size x by the equation w = Cxm [I] In this equation C and m are experimental constants. A plot of weight retained against particle size is a straight line of slope m if the scales for x and w are both logarithmic. In the fine range, the slopes of the size-distribution graphs plotted according to the method described above vary within a limited range. An inspection of a number of size-distribution data by various experimenters indicates that the slope very seldom exceeds 1.0, but is usually greater than 0.7. More recently, schuhmann8 proposed a method of charting that has so many advantages of its own that it has been used primarily in this work. For fine particles Schuhmann has found that the data are represented by the equation (x)m k [2]

Jan 1, 1947

By A. M. Gaudin, R. T. Hukki

Previous work on the principles of comminution has shown: (I) that the surface produced is proportional to work input (Rittinger law,1a-3); (2) that there is regularity to the weight distribution of the fragments according to size.4-10 In this paper it is brought out that the surface on the fragments is distributed in definite and simple relation to size. The experimental work has involved: I. Construction of an apparatus capable of measuring the surface of mineral fragments independently of the chemical composition of the fragments and independently of the site of the surface; 2. Refining the methods available for measurement of particle size; 3. Designing and building a crusher capable of operating on very small quantities of mineral, if necessary on single crystals, and in such fashion as to minimize handling losses of material. Complete experiments have been carried out with massive quartz and individual quartz crystals. partial experiments, lacking surface measurements, have been made with glass spheres, galena, sphalerite, fluo-rite, salt and coal. Introduction The existence of regularity in weight distribution with size was noted many years ago, especially by A. 0. Gates;' the subject was also studied in detail by one of us.6 In the latter paper it was shown that rocks can be divided into two classes: homogeneous rocks, which show no preferential breaking, and heterogeneous rocks, which show preferential breaking at the grain size of the rock. It was shown, furthermore, that the fragments obtained by rupturing a homogeneous rock occur (in the fine range) in such abundance as to permit the writing of a relatively simple equation to relate the weight retained on a screen to the screen opening. With screens of which the openings are in constant ratio, the weight retained, w, is related to the screen size x by the equation w = Cxm [I] In this equation C and m are experimental constants. A plot of weight retained against particle size is a straight line of slope m if the scales for x and w are both logarithmic. In the fine range, the slopes of the size-distribution graphs plotted according to the method described above vary within a limited range. An inspection of a number of size-distribution data by various experimenters indicates that the slope very seldom exceeds 1.0, but is usually greater than 0.7. More recently, schuhmann8 proposed a method of charting that has so many advantages of its own that it has been used primarily in this work. For fine particles Schuhmann has found that the data are represented by the equation (x)m k [2]

Jan 1, 1947

By Harry L. Brown, James M. Dickinson, Philip E. Armstrong

The elastic stiffness coefficients of niobium have been rneaslrred from -150°C to over 650 C and ave in accord with the anomalous temperature dependence previously observed for Young's modulus. This unusual behavior has been shown to be the result of changes in the relative values of the shear elastic coefficients. The bulk modulus remained essentially constant over the temperature range studied, while changes in the shear coefficients produced a more nearly isotropic behavior as the temperature increased. A number of investigators have reported data on the temperature dependence of Young's modulus of polycrystalline niobium. The values cited for the room-temperature modulus ranged from 0.71 to 1.17 x 10" dynes-cm-' (10.3 to 17.0 x lo6 psi) and in each case the modulus was observed to decrease with increasing temperature. In our recent study,8 both polycrystalline and single-crystal samples of essentially strain-free high-purity niobium showed a Young's modulus whose temperature dependence as well as magnitude was strongly dependent on specimen orientation. This was shown to be the result of changes in the relative magnitude of the two shear moduli, C and C'. Young's modulus of polycrystalline samples with strong [110] textures and Young's modulus of single crystals whose orientations were away from the [loo] actually increased as much as 12 pct between room temperature and 1000°C. While studies on the residual effects of previous fabrication, thermal treatments, and impurity contents will probably resolve the problem of the widely differing Young's modulus values observed in polycrystalline niobium, a more complete description of the elastic properties requires an evaluation of the single-crystal elastic constants. A knowledge of these constants can provide a clearer picture of the nature of the temperature dependence, as well as establish a basis for predicting the modulus behavior of polycrystalline niobium, both in the randomly oriented condition and with various fabrication textures. The effects of residual strains on the elastic behavior then can be separated from orientation effects. EXPERIMENTAL METHOD Thin rod-resonance techniques were used to obtain both the Young's modulus and shear modulus of single-crystal specimens. The determination of these moduli as functions of the crystallographic orientation of the specimen axis provided sufficient information to permit calculation of the single-crystal elastic constants. The necessity for torsional as well as longitudinal measurements led to the design and assembly of a vertical-tube vacuum furnace incorporating probes for the simultaneous determination of both longitudinal

Jan 1, 1967

By E. C. Houston

THE presence in the Tennessee Valley of extensive deposits of olivine, a silicate of magnesium and iron that contains approximately 28 per cent magnesium, has been recognized since 1896 when Lewis8 published a survey of basic magnesium rocks of western North Carolina. A recent field survey by T.V.A 7 showed that more than two hundred million tons of high-grade olivine occurs above local drainage levels in western North Carolina and northern Georgia. Except for sporadic attempts to work the olivine for its nickel and chromium contents,10 the ore received little attention industrially until 1926 when Goldschmidt3 suggested its use in the manufacture of refractories. Only one instance is recorded of an attempt to utilize the ore commercially for its magnesium content;" in this case a process was used in which olivine was treated with sulphuric acid, the resultant mixture was leached with water, and the leach solution was purified and evaporated to form epsom salts, which was the end product. As a part of its program of contributing to the development of the natural resources of the region, the Tennessee Valley Authority became interested in the olivine deposits as a source of metallic magnesium because of their high magnesium content and proximity to hydroelectric power. Studies were undertaken to determine the feasibility of producing magnesium chloride by extraction of olivine. The experimental work was carried out successively at the T.V.A. Minerals Testing Laboratory, Norris, Tenn., at the Georgia State Engineering Station,* Atlanta, Ga., and at the T.V.A. laboratory at Wilson Dam, Ala. The present paper describes a process, developed through the pilot-plant stage, whereby magnesium chloride suitable for reduction to metallic magnesium can be prepared from olivine by extraction with hydrochloric acid and subsequent purification. Research on the magnesium-from-olivine process, originally intended for peacetime use, was given impetus by the shortage of magnesium that existed at the beginning of the current world war. By the time the process was sufficiently developed to justify a proposal for its inclusion in the war program, the shortage had been met by expansion and development of other processes. However, it is believed that the magnesium-from-olivine process may have advantages that will warrant consideration of its use after the war, when the economics of the various processes rather than production on a wartime scale will be the criterion for commercial production of magnesium. DESCRIPTION OF PROCESS Metallic magnesium is produced electrolytically by the Dow and the Elektron

Jan 1, 1945

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 George M. Rigg, Samuel M. Cassidy

During 1937 a program was begun to mechanize and modernize the then 28-year old Isabella mine of the Weirton Coal Co., which is on the Monongahela River, in Fayette County, Pennsylvania, at one edge of what is generally known as the Coke Region. Weirton Coal Co. is a subsidiary of the National Steel Corporation, and produces metallurgical grade coking coal for the Weirton Steel Co., Weirton, W. Va. Improvements subsequently made included a cleaning plant for washing the entire mine output, shovel-action track-mounted machines for mechanically loading all the coal, universal-type track-mounted cutting and shearing machines, post drills, 8-wheel mine cars of 10 tons capacity, cable-reel gathering locomotives and other auxiliary equipment. This paper presents the factors, reasons and results of decided changes from the mining system generally prevailing in the region, as well as abandonment of selective mining practices in favor of complete seam extraction. Coal-seam Conditions Fig. 1 illustrates the Pittsburgh coal seam on the property. Cover over the seam averages 450 ft., and 675 ft. is the maxi- mum. Main roof varies from very weak to medium strong; usually it disintegrates rapidly on exposure to air. The "wild" coal makes a fairly strong immediate roof if supported by crossbars and if unbroken affords a seal to the main roof. The draw slate is very weak and treacherous. The floor is characterized by numerous irregular bottom rolls, or "horsebacks," protruding from a few inches up to 3 ft. into the coal. Some are soft, but many are hard and flintlike. Although the bottom slate usually is hard, the underlying fire clay causes it to buckle and heave readily with any moderate increase in roof pressure or where damp. As a whole, the bottom is weaker than the main roof. The coal is characterized by numerous closely jointed face and butt cleats and a woody, springy nature when shot, both having a decided influence on face practices. As shown in Fig. I, at both the top and bottom of the main coal seam is a layer of coal of higher ash and sulphur content than the body of coal in the middle. Factors That Influence the Mining System Equipment was bought and organization for mechanical loading was made on the basis of working each mechanical unit as near its full capacity as possible, to lessen investment cost and obtain best operating efficiency. This led to combination double and triple-shift operation at the start, and, very shortly, to all sections being triple shifted.

Jan 1, 1947

By Samuel M. Cassidy, George M. Rigg

During 1937 a program was begun to mechanize and modernize the then 28-year old Isabella mine of the Weirton Coal Co., which is on the Monongahela River, in Fayette County, Pennsylvania, at one edge of what is generally known as the Coke Region. Weirton Coal Co. is a subsidiary of the National Steel Corporation, and produces metallurgical grade coking coal for the Weirton Steel Co., Weirton, W. Va. Improvements subsequently made included a cleaning plant for washing the entire mine output, shovel-action track-mounted machines for mechanically loading all the coal, universal-type track-mounted cutting and shearing machines, post drills, 8-wheel mine cars of 10 tons capacity, cable-reel gathering locomotives and other auxiliary equipment. This paper presents the factors, reasons and results of decided changes from the mining system generally prevailing in the region, as well as abandonment of selective mining practices in favor of complete seam extraction. Coal-seam Conditions Fig. 1 illustrates the Pittsburgh coal seam on the property. Cover over the seam averages 450 ft., and 675 ft. is the maxi- mum. Main roof varies from very weak to medium strong; usually it disintegrates rapidly on exposure to air. The "wild" coal makes a fairly strong immediate roof if supported by crossbars and if unbroken affords a seal to the main roof. The draw slate is very weak and treacherous. The floor is characterized by numerous irregular bottom rolls, or "horsebacks," protruding from a few inches up to 3 ft. into the coal. Some are soft, but many are hard and flintlike. Although the bottom slate usually is hard, the underlying fire clay causes it to buckle and heave readily with any moderate increase in roof pressure or where damp. As a whole, the bottom is weaker than the main roof. The coal is characterized by numerous closely jointed face and butt cleats and a woody, springy nature when shot, both having a decided influence on face practices. As shown in Fig. I, at both the top and bottom of the main coal seam is a layer of coal of higher ash and sulphur content than the body of coal in the middle. Factors That Influence the Mining System Equipment was bought and organization for mechanical loading was made on the basis of working each mechanical unit as near its full capacity as possible, to lessen investment cost and obtain best operating efficiency. This led to combination double and triple-shift operation at the start, and, very shortly, to all sections being triple shifted.

Jan 1, 1947

By D. J. DeLazaro, D. W. Levinson

Observations were made of the isothermal transformation and quench and reheat transformation characteristics of binary titanium alloys containing nominally 6 wt pct and 10 wt pct Mn at temperatures of 700°, 600°, 500°, and 400°C. A large change in electrical resistivity attends the beta to alpha transformation in these alloys. The correlation between the resistivity and microstructure provides a very sensitive means of following the transformation. IN a recent paper, Wyatt' determined the electrical resistivity of several grades of unalloyed titanium metal as a function of temperature. In addition to the expected discontinuity accompanying the a-B transformation, it was shown that s-Ti has a much larger temperature coefficient of resistance than 8. The result would be a very large change in resistivity attending ß?a: transformation if it were possible to retain the ß structure at room temperature in pure titanium. From these data, it was reasoned that this very large resistance change should accompany the decomposition of the ß phase in alloys in which the ß phase can be retained by quenching to room temperature from the ß field. This effect is illustrated schematically in Fig. 1. Binary Ti-Mn alloys containing more than 5 wt pct Mn can be quenched to retain ß from the ß field. While the ß phase would be expected to transform in these alloys to a + TiMn via a eutectoid reaction,' it has been observed that the eutectoid decomposition does not occur readily in hypoeutectoid alloys, but rather the decomposition of the ß occurs by rejection of proeutectoid a only." Thus, the resistivity should show a marked decrease, as the a: phase is rejected from ß and a study of the resistivity of solution treated and isothermally transformed or quenched and reheated alloys should provide an excellent means of establishing the transformation kinetics of these alloys at various temperatures. The usual metallographic method of determining the transformation temperature-time characteristics of alloys of this type is very satisfactory for deter- mining the time required to initiate the rejection of the a phase at temperatures relatively close to the ß/a: + ß boundary when the rejected a is coarse, and a typical Widmanstaetten structure is produced. The metallographic method is less satisfactory for this purpose at lower temperatures where a fine nodular decomposition product is observed and is very unsatisfactory for the determination of the time required to complete the transformation at any temperature. Accordingly, specimens were prepared for resistivity measurements in order to determine the transformation characteristics of the alloys.

Jan 1, 1955

By W. T. Cardwell

This paper presents a theory for estimating the rate of gravity drainage of a liquid out of a sand column. Account is taken of the variation in permeability to the liquid as the saturation in the upper part of the sand becomes less than 100 pct. The theory is confirmed by previously published experimental data. Introduction Petroleum engineers have expressed the need for 4 theory of gravity drainage. Brunner,' in particular, has pointed out that some type of mathematical theory is necessary to begin the application of laboratory data to field problems. Muskat and his associates2'3-4 have recently made contributions to the theory of gas-drive behavior and have indicated an intention to apply their methods to water-drive systems. No theory of gravity drainage rates has been developed, however, and it seems desirable to formulate one at this time. Differential Equations of Capillary Flow The flow of liquids in partially saturated porous media has been studied by many investigators.6-10 Richards6 presented derivations of fundamental differential equa- tions governing two-phase capillary flow; and used simplified forms of those equations in solving a steady-state problem. Muskat and Meres6 presented and used equations different from those of Richards. Their equations did not explicitly involve capillary pressure gradients; but included, on the other hand, terms expressing the effects of the evolution of gas from the liquid phase during flow. Leverett8 stated in 1940 that "previous work on the flow of fluid mixtures in porous solids [had] failed adequately to account for all of the three influences that cause motion of the fluids: capillarity, gravity, and impressed external pressure differentials." Leverett's basic equations, however, were specialized forms of the general equations of Richards,5 which had actually taken account of the three influences mentioned by Leverett, but had not been used in a problem involving all three. The fact is that our knowledge of capillary flow and our ability to express this knowledge in differential equations exceed our ability to solve the equations except in a few cases. General differential equations have usually been of little more than formal value. In solving practical problems, it has been necessary to develop specific equations, preserving terms that involved the factors important in those problems, and purposefully neglecting other terms that were not of predominating influence. This is the method followed here. It is believed that the solution of the particular problem and the scheme of the solution itself are new.

Jan 1, 1949

By Arthur L. Christenson, Clarence E. Jackson

In the establishment of the relationship between weldability and hardenability, two methods have been employed in correcting for the grain growth produced in the heat-affected zone: first, the hardenability calculated from chemical composition* may be corrected to the grain size observed in an actual weld? or, second, a hardenability test may be made on the steel quenched from a temperature high enough to produce a grain size comparable to that found in the heat-affected zone.8 In order to obtain grain sizes in the end-quench hardenability bar comparable to those resulting in the base metal from the welding cycle, a quenching temperature of 2Ioo°F. has been used. In studies of the end-quench hardenability specimen quenched from 2Ioo°F. instead of from a lower temperature of I7OO°F., it is impor-TaiiT to ascertain The relative cooling rates for various distances along the bar. It is a question as to whether the cooling occurs at the same rate or whether there is any significant difference from the standard cooling-rate curve published by Jominy and confirmed by others.4,5 This paper reports experimental evidence concerning the effect of quenching temperature on the cooling rates in the end-quench hardenability test. The effect of quenching temperatures on cooling rates has been studied by a number of investigators.6'7 French has considered this effect from both theoretical and experimental aspects. In French's studies on complete quenching of spheres and rounds, an increase in the quenching temperature caused an increase in the cooling rate at 720°C. at the center of the specimen. The center cooling velocity also has been shown to be dependent upon the surface per unit volume for the type of specimens studied; the velocity of cooling increases with an increase in the surface per unit volume. Three methods of indicating the rapidity of cooling of a body of metal during a quenching operation have been propped: I. The time it takes for the metal to cool from the quenching temperature to a temperature halfway between the quenching temperature and the temperature of the quenching medium (half-temperature time): Grossmann, Asimow and Urban7 justify the use of this criterion by the fact that the half-temperature time includes the temperature and time of incubation as well as the zone of formation of pearlite and, further, the data so derived accord very closely with experimental values. 2. The time interval the metal remains in a given temperature range; for example,

Jan 1, 1944

By Arthur L. Christenson, Clarence E. Jackson

In the establishment of the relationship between weldability and hardenability, two methods have been employed in correcting for the grain growth produced in the heat-affected zone: first, the hardenability calculated from chemical composition* may be corrected to the grain size observed in an actual weld? or, second, a hardenability test may be made on the steel quenched from a temperature high enough to produce a grain size comparable to that found in the heat-affected zone.8 In order to obtain grain sizes in the end-quench hardenability bar comparable to those resulting in the base metal from the welding cycle, a quenching temperature of 2Ioo°F. has been used. In studies of the end-quench hardenability specimen quenched from 2Ioo°F. instead of from a lower temperature of I7OO°F., it is impor-TaiiT to ascertain The relative cooling rates for various distances along the bar. It is a question as to whether the cooling occurs at the same rate or whether there is any significant difference from the standard cooling-rate curve published by Jominy and confirmed by others.4,5 This paper reports experimental evidence concerning the effect of quenching temperature on the cooling rates in the end-quench hardenability test. The effect of quenching temperatures on cooling rates has been studied by a number of investigators.6'7 French has considered this effect from both theoretical and experimental aspects. In French's studies on complete quenching of spheres and rounds, an increase in the quenching temperature caused an increase in the cooling rate at 720°C. at the center of the specimen. The center cooling velocity also has been shown to be dependent upon the surface per unit volume for the type of specimens studied; the velocity of cooling increases with an increase in the surface per unit volume. Three methods of indicating the rapidity of cooling of a body of metal during a quenching operation have been propped: I. The time it takes for the metal to cool from the quenching temperature to a temperature halfway between the quenching temperature and the temperature of the quenching medium (half-temperature time): Grossmann, Asimow and Urban7 justify the use of this criterion by the fact that the half-temperature time includes the temperature and time of incubation as well as the zone of formation of pearlite and, further, the data so derived accord very closely with experimental values. 2. The time interval the metal remains in a given temperature range; for example,

Jan 1, 1944

By C.R. Taylor, John Chipman

The study of chemical reactions of liquid steel and basic open-hearth slag involves a complex slag system of at least eight important components, and often a number of others. In initiating an experimental program on the equilibrium relationship of slag and metal, it became evident that but little progress could be expected in the interpretation of the complex slags until an understanding had been gained of the simpler liquid systems composed of a limited number of slag constituents. The simplest system that in any way resembles open-hearth slag must contain lime, silica and iron oxide. Attempts to produce in an induction furnace slags containing only these constituents have met with serious limitations because of the solubility of refractories in the slag. Thus in acid-lined furnaces the slag is always saturated with silica and consequently contains between 48 and 63 per cent of this component. In basic-lined furnaces an undesired additional component, magnesia, is introduced to the extent of some 3 to 15 per cent, depending upon the acidity, sometimes with disastrous results to the furnace. Thus in a magnesia-lined furnace, Fetters and Chipman1 found it impossible to prepare slags in which the ratio (CaO + MgO)/SiO2 was less than that corresponding to the metasilicate (approximately 0.8:I). Between this composition and that of the true acid slags lies a field of composition about which very little is known and which cannot be explored by any ordinary means. This circumstance, as well as the desire to study the more basic slags in the absence of magnesia, calls for the development of a method by which slags may be brought into equilibrium with molten metal without coming in contact with refractory. Such a technic has been provided by the rotating induction furnace developed by Barrett, Holbrook and Wood.2 Three modifications of the rotating furnace were described by these authors. The first was essentially a rotating refractory cylinder containing the magnesia crucible, which was itself heated by a graphite crucible. In the second, only the magnesia crucible rotated, the cylindrical graphite heater being stationary. In the third, the coil and crucible revolved, and the metal was heated directly by induction. Experimental Method Furnace The furnace used in this investigation differed from previous designs and may be Sci- a fourth modification of the original rotating furnace. Its essential fea tures are shown in Fig. I' The Outer case A is a fire-clay flue liner for control of the atmosphere. The top B and base 6 are alberene stone. The coil supports D are of ""Formica," a material formed from phe-

Jan 1, 1943

By C. R. Taylor, John Chipman

The study of chemical reactions of liquid steel and basic open-hearth slag involves a complex slag system of at least eight important components, and often a number of others. In initiating an experimental program on the equilibrium relationship of slag and metal, it became evident that but little progress could be expected in the interpretation of the complex slags until an understanding had been gained of the simpler liquid systems composed of a limited number of slag constituents. The simplest system that in any way resembles open-hearth slag must contain lime, silica and iron oxide. Attempts to produce in an induction furnace slags containing only these constituents have met with serious limitations because of the solubility of refractories in the slag. Thus in acid-lined furnaces the slag is always saturated with silica and consequently contains between 48 and 63 per cent of this component. In basic-lined furnaces an undesired additional component, magnesia, is introduced to the extent of some 3 to 15 per cent, depending upon the acidity, sometimes with disastrous results to the furnace. Thus in a magnesia-lined furnace, Fetters and Chipman1 found it impossible to prepare slags in which the ratio (CaO + MgO)/SiO2 was less than that corresponding to the metasilicate (approximately 0.8:I). Between this composition and that of the true acid slags lies a field of composition about which very little is known and which cannot be explored by any ordinary means. This circumstance, as well as the desire to study the more basic slags in the absence of magnesia, calls for the development of a method by which slags may be brought into equilibrium with molten metal without coming in contact with refractory. Such a technic has been provided by the rotating induction furnace developed by Barrett, Holbrook and Wood.2 Three modifications of the rotating furnace were described by these authors. The first was essentially a rotating refractory cylinder containing the magnesia crucible, which was itself heated by a graphite crucible. In the second, only the magnesia crucible rotated, the cylindrical graphite heater being stationary. In the third, the coil and crucible revolved, and the metal was heated directly by induction. Experimental Method Furnace The furnace used in this investigation differed from previous designs and may be Sci- a fourth modification of the original rotating furnace. Its essential fea tures are shown in Fig. I' The Outer case A is a fire-clay flue liner for control of the atmosphere. The top B and base 6 are alberene stone. The coil supports D are of ""Formica," a material formed from phe-

Jan 1, 1943

By Jim Douglas, H. H. Rachford, D. W. Peaceman

The problem of unsteady-state gas flow through porous media has been solved numerically only for the case of linear or radially symmetric reservoirs. A recently introduced numerical method for solving the unsteady-state heat flow equation in two dimensions is applied to the calculation of the depletion of a square region containing a perfect gas. Solutions are presented in graphical form for various values of dimensionless parameters. The solutions are compared with published .solutions for radial reservoirs. I NTR ODUCTION The problem of unsteady-state flow of gas through porous media gives rise to a second-order non-linear partial differential equation for which no analytical solution has been found. Numerical approximations to solutions of the gas flow problem have been obtained by the stepwise solution of an associated difference equation1,2. However, the methods so far developed have required that the reservoir be either linear or radially symmetric. This restriction in shape has been necessary so that only two independent variables be considered, namely, one distance variable and time. In order to deal with reservoirs having more realistic shapes, it is necessary to develop numerical procedures for the solution of the gas flow problem involving two distance variables. A numerical procedure, denoted as the alternating-direction implicit method, for the solution of the heat-flow problem in two dimensions has recently been introduced" By the use of this procedure, approximate solutions have been obtained for heat-flow problems in a square8, and in regions having various non-rectangular boundariesa. Because of the similarity between the equation for heat conduction in solids and the equation for gas flow in porous media, it is reasonable to expect that the alternating-direction implicit method should also be useful for solving the gas flow problem in various two-dimensional regions. Solutions have been calculated for the simplest two-dimensional region, a square reservoir with a single well in the center. While reservoirs of such simple geometry seldom, if ever, exist, the solution of this problem is of some practical importance because it is also the solution of another problem, that of determining the depletion history about an individual well in an infinite uniform reservoir containing wells spaced throughout on a square lattice and producing equally from each well. Finally, it is of interest to compare solutions for a square reservoir with those for a circular reservoir and to determine the effect of the shape of the boundary for that particular case. METHOD OF CALCULATION Basic Differential Equation By combining the equation of continuity, the perfect gas law,

Jan 1, 1956

By R. F. Evans, J. M. Avert

Much has been written of the glamour of magnesium from sea water, the Aladdin-like creation of a huge magnesium plant in the Nevada desert using cheap hydroelectric power from Boulder Dam; the marvels of the Hansgirg process for the electrothermal reduction of magnesium oxide by carbon, and the ferrosilicon process for producing magnesium from dolomite. This is the story of the production of magnesium by the electrolytic process, using steam-electric power supplied by a public utility, in a plant at Painesville, Ohio, 30 miles east of Cleveland on the shore of Lake Erie. The story is not without interest, since it involves several unique developments that provide the answer to a question frequently asked: How is it possible to produce magnesium metal economically at such a location as Painesville, Ohio? Basically, the answer lies in making use of facilities already in existence for the production of soda ash, which makes it possible to manufacture magnesium chloride, the principal raw material, cheaply enough to offset the high cost of electric power. To this is coupled the successful conversion of by-product chlorine into a product required for the war program. The source of magnesium for this opera- tion is the enormous surface deposit of high-grade dolomite in the region south of Toledo, within reasonable freight haul of Painesville. This same geological stratum underlies the Painesville plant, but unfortunately at a depth of about 3000 ft.— apparently too great a depth to permit underground mining to compete with the delivered cost of rock from surface quarries in other areas. The cost of dolomite obviously is an important factor, since the rock contains only some 12 per cent magnesium (20 per cent MgO) so that one dollar on the cost of stone means more than $8 in terms of its magnesium content, and more than that in terms of recoverable magnesium metal. Production of Magnesia from Dolomite In the summer of 1941, the Diamond Alkali Co. was well along with construction of a plant intended for the commercial production of refractory and other grades of magnesia from dolomite. The process to be used was designed to make maximum economic advantage of existing plant and operations by tying the production of magnesia in with the manufacture of soda ash in such a way as to make use of the lime [CaO)., value of calcined dolomite. The process finally adopted after a lengthy research and development program has much in common with the old Clerc-Nihoul process, but includes certain innovations found to be necessary or advantageous. Essentially, the process is based upon the following series of reactions:

Jan 1, 1949

By C. R. Taylor, John Chipman

THE study of chemical reactions of liquid steel and basic open-hearth slag involves a complex slag system of at least eight important components, and often a number of others. In initiating an experimental program on the equilibrium relationship of slag and metal, it became evident that but little progress could be expected in the interpretation of the complex slags until an understanding had been gained of the simpler liquid systems composed of a limited number of slag constituents. The simplest system that in any way resembles open-hearth slag must contain lime, silica and iron oxide. Attempts to produce in an induction furnace slags containing only these constituents have met with serious limitations because of the solubility of refractories in the slag. Thus in acid-lined furnaces the slag is always saturated with silica and consequently contains between 48 and 63 per cent of this component. In basic-lined furnaces an undesired additional component, magnesia, is introduced to the extent of some 3 to 15 per cent, depending upon the acidity, sometimes with disastrous results to the furnace. Thus in a magnesia-lined furnace, Fetters and Chipman1 found it impossible to prepare slags in which the ratio (CaO + MgO)/SiO2 was less than that corresponding to the metasilicate (approximately 0.8: I). Between this composition and that of the true acid slags lies a field of composition about which very little is known and which cannot be explored by any ordinary means. This circumstance, as well as the desire to study the more basic slags in the absence of magnesia, calls for the development of a method by which slags may be brought into equilibrium with molten metal without coming in contact with refractory. Such a technic has been provided by the rotating induction furnace developed by Barrett, Holbrook and Wood.2 Three modifications of the rotating furnace were described by these authors. The first was essentially a rotating refractory cylinder containing the magnesia crucible, which was itself heated by a graphite crucible. In the second, only the magnesia crucible rotated, the cylindrical graphite heater being stationary. In the third, the coil and crucible revolved, and the metal was heated directly by induction. EXPERIMENTAL METHOD Furnace The furnace used in this investigation differed from previous designs and may be considered a fourth modification of the original rotating furnace. Its essential features are shown in Fig. I. The outer case A is a fire-clay flue liner for control of the atmosphere. The top B and base C are alberene stone. The coil supports D are of "Formica," a material formed from phe-

Jan 1, 1942

By A. H. Daane, B. J. Beaudry

The yttl-irtm-nickel system has been investigated by metallo-graphic, thermal ard X-ray methods. There are nine intermetal-lic compounds present: Y3Ni, Y3Ni,, YNi,, YNi,, Y,Ni,, YNi,, and Y,Nil, which rodergo peritectic decomposition and YNi and YNi, which melt congruently. There are eutectics at 34.8, 57.5 and 93.3 at pct Ni which melt at 805°, 950 and 1285 C, respectively. Crystallographic data are given for YNi, YNi,, YNi,, YNi5and Y,Ni,. The terminal solid solubility is low. In recent work by Fisher and Fullhart' in which yttrium crucibles to be used for containers of uranium-chromium eutectic were clad with a high nickel steel, a low melting phase formed where the yttrium was in contact with the steel. To investigate the cause of this phenomenon, Daane, et al. made a survey study of yttrium systems with chromium, manganese, iron, and nickel and found an 18 wt pct Ni (weight percent) alloy to melt at approximately 950°C. voge13 in a study of the systems of cerium, lanthanum, and praseodymium with nickel found six compounds of the same formula in each system, i.e., R3Ni, RNi, RNiz, RNi3, RNi4, and RNi5. Since there is a great similarity between yttrium and the rare earths, compound formation was likely to occur also in the yttrium-nickel system. voge13 observed that the ability of transition metals to form compounds with the rare earths diminishes in the order nickel, cobalt, and iron while no compounds are formed with manganese, chromium, and titanium. Available data on yttrium systems with these elements indicate similar behavior, except that a slightly greater tendency toward compound formation is apparent. Simple eutectics with limited solid solubility have been found in the yttrium-titanium4 and yttrium-chromium5 systems, but at least one compound is present in the yttrium-manganese system.' In the case of yttrium-iron, at least three compounds are present,5 while only two are present in the cerium-iron,' and no compounds are present in the lanthanum-iron5 system. On the basis of both the trend in the alloying behavior of yttrium and rare-earth metals with the first transition series metals and the large number of compounds in the cerium-nickel system, one might expect six or more compounds to form in the nickel-yttrium system. A consideration of Hume-Rothery's rules of alloying based on size factor, electronegati-vity, and valence predicted low terminal solid solubility and possible compound formation. The present study was undertaken to confirm these predictions of

Jan 1, 1961