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By Ebert L. J., G. Sachs, Jr. Brown W. F.

It is a generally recognized fact that a steel quenched from the austenitic range and tempered to yield a structure composed of tempered martensite becomes increasingly more ductile with increasing tempering temperature. However, the conventional tensile test fails to yield any value that is sensitive to differences in behavior on tempering among the various low-alloy steels or among different heats of a particular steel. The notched impact bending test, on the other hand, has been recognized for a considerable length of time as capable of revealing differences in impact properties among various steels tempered to 'the same strength level (i.e., the same tensile strength in a conventional tensile test). However, this test is very complex and its significance has not been clarified up to the present time. Of its three characteristic features—the high speed, the notch, and the bending—the notch has been found by Davidenkov2 to be the most potent embrittling factor. Recent investigations on low-alloy steels have shown static notch-bar tensile tests to be more lucid and to evaluate the metal properties in much the same manner as impact tests. In an attempt to analyze the fundamental nature of this test, it was found possible to separate the effects of the two basic characteristics of the stress pattern introduced by the presence of a circumferential notch, the stress state and the high initial stress concentration at the notch bottom. The major conclusions drawn from these previous investigations were as follows: I. The magnitude of the triaxiality at fracture depends primarily on the initial notch depth. Its effect is a great reduction in the average ductility (contraction in area at fracture in the notched section) as compared with that observed in uniaxial tension. This triaxial stress state occurs at a point in the interior of the notch specimen. It determines the notch ductility if the notch is mild and/or the metal possesses a considerable ductility. On the contrary, brittle specimens probably fracture on the metal surface (at the notch bottom) at which point biaxial stress state is present. This biaxiality also considerably reduces the ductility of the metal. For small notch ductilities the notch strength and the notch ductility become very sensitive to embrittling factors. This is contrary to the behavior. of the ductility values derived from a conventional tensile test, which are comparatively insensitive.

Jan 1, 1947

By D. C. Lindley, D. H. Gaucher

The displacement of oil by water in a waterflood project is accomplished by the action of transient viscous, gravitational and capillary forces which drive fluid through interconnecting pore spaces toward production wells. The relative importance of each of these forces to the effectiveness of the displacement and the production history depends on properties of the reservoir itself and the manner in which it is operated. There has been considerable discussion'-3 concerning the importance of these factors and the extent to which they control the performance of individual waterflood projects. No data have been presented, however, to demonstrate the effect on waterflood behavior of variations in rock permeability, water-injection rates and mobility ratios in three-dimensional reservoir systems in which viscous, gravitational and capillary forces are allowed to assume the proper relative influence on fluid flow. Much information relevant to water flooding has been gained from the study of field case histories. But, the complexity of the systems involved, the difficulty of defining geometry and obtaining sufficient data, and the fact that the same reservoir is never flooded twice with the same initial conditions, all obscure the role of process variables such as rate. Further, mathematical calculations of waterflood behavior are restricted at this time by available mathematical techniques to highly simplified situations. Scaled models, however, do offer an approach at the present time to evaluation of the effects of the pertinent variables. Several investigators have predicted prototype reservoir behavior from observations of model waterflood performance under a variety of conditions. Two-dimensional aspects of waterflood pattern efficiency have been investigated by Muskat, Aronofsky, Dyes, et al, raig, et al,' and Rapoport, et al. he effects of gravity segregation, viscous fingering and permeability stratification have also been studied in two-dimensional models. Craig, et al," studied the importance of gravitational forces on frontal displacement in three-dimensional models with wells on a five-spot pattern. This work in- vestigates the tendency for water to segregate in homogeneous reservoirs because of gravity and to under-run the oil for a range of water-inject ion rates. The effects of permeability stratifications were investigated by these authors using miscible fluids to simulate water-channeling through permeable strata in systems of negligible capillary force. In this investigation, a three-dimensional model of a five-spot pattern flood was designed to represent typical prototype conditions, and the sand and liquid properties were selected so that capillary, gravitational and viscous pressure gradients were scaled. It was not, however, possible to achieve exact similitude regarding viscous fingering when the more viscous oil was used. The effects of rock stratification on waterflood behavior were studied by changing both the permeability ratio and the position of the more permeable sand stratum in a two-layered, horizontal model. For each type of stratification, constant-rate floods were performed and the rates were varied, in separate experiments, over a tenfold range. To observe the effect of mobility ratio on flood performance, two series of constant-injection-rate floods were performed on the most highly stratified reservoir at a water-oil viscosity ratio of one.

By J. T. Michalak, H. W. Paxton

The recovery of the initial flow stress of poly-crystalline iron is characterized by a) a logarithmic time dependence; b) an increasing activation energy with increasing recovery; c) an increased ?,ate and fraction of recovery with decreased temperature of deformation; and d) an increased rate with increased deformation. Isochro)ml studies of the recovery of single crystals revealed more sluggish recovery. The original flou3 stress of single crystals could be regained by recovery anneals at 800"or 900°C. ThE great majority of the theoretical treatments and experimental studies of strain-hardening have been concerned with the close-packed lattices.' Very little effort has been expended on the bcc structure so that the theory of work-hardening of this lattice is essentially nonexistent. The limited amount of experimental data resulting from the direct studies on silicon-iron,2 low-carbon steel,3 and purified irons4"7 does not as yet permit a detailed analysis of the strain-hardening. Studies concerned with the effects of annealing following deformation have been few in number," have been somewhat limited in extent, and have had the disadvantage of using irons containing a substantial impurity content. The present research was undertaken to augment the limited knowledge we have of the characteristics of a bcc metal as regards strain-hardening and recovery from the strain-hardened state. The recovery of the flow stress has been employed since it was felt that the stress associated with the hardened state gives at least a fair qualitative description of the state of the imperfections causing the hardening. The study was concerned primarily with the recovery of flow stress following strain-hardening of polycrys-talline, zone-melted iron as a function of the amount of deformation, the temperature of deformation, and the time and temperature of the recovery anneal. A limited investigation of the recovery of the initial flow stress of single crystals of this same material as a function of the recovery temperature was also conducted in conjunction with the Lambot X-ray technique." MATERIAL The zone-melted iron used in this investigation was obtained through the courtesy of the American Iron and Steel Institute and Battelle Memorial Institute. The analysis, as given by the supplier indicated a maximum impurity content of 0.02 wt pct excluding those impurities listed in Table I. (The actual impurity content is very probably less than this since detection limits were considered as the amount of a particular impurity level.) Also listed in Table I are the interstitial impurity contents of the iron at various stages of experimental work indicating that these im-

Jan 1, 1962

By J. Chipman, N. J. Grant, J. H. Walsh, T. B. King

WITH the development of adequate sampling and analysis techniques, much information has been obtained concerning the behavior of hydrogen in the steel bath during the course of steelmak-ing operations. From studies of this type it has become clear that the slag has an important role to play in determining the hydrogen content found in commercial products. A knowledge of the behavior of hydrogen in slags is necessary to round out our knowledge of hydrogen in steelmaking practice; with this information we are better able to assess practical methods of control. In this paper a method developed for analyzing slags for hydrogen content, studies of the solubility of hydrogen in synthetic slags, and studies of the variation of hydrogen content in slag and steel in industrial heats will be described. Previous Work—While very little has been done in the past to determine the hydrogen content of metallurgical slags, measurements have been made on such slag-like materials as geologic magmas and glasses. Goranson as made extensive studies of the solubility of water in natural and synthetic granites. Many workers have investigated the solubility of gases in synthetic and commercial glasses, but the recent work of Russell" is the most extensive. Russell found that the solubility of water in glass was proportional to the square root of the water vapor pressure in water vapor-oxygen mixtures. It was found that the solubility could either increase or decrease with temperature depending on the glass composition. Wentrup, Fucke, and Rief,' and Piper, Hagedorn, and Backes' have extracted hydrogen by holding a slag at 1300" and 800°C respectively in vacuum. Wentrup et al. reported hydrogen and water vapor as evolved together while Piper et al. passed the evolved gases from the hot extraction treatment over hot ferromanganese to reduce the evolved water vapor to hydrogen and, therefore, reported the analyses in terms of total dissolved hydrogen. Yavoiskii has reported hydrogen and nitrogen analyses on steelmaking slags. Dobrokhotov, Povol-skii, and Khan have studied the hydrogen content of basic open hearth steel under slags of varying viscosity. These authors reported that the hydrogen content of the steel bath increased as the fluidity of the slag was increased by the addition of bauxite. They recommended that a viscous slag be used and the steel tapped without deoxidation in the furnace to ensure a low final hydrogen content. Analysis of Slags for Hydrogen Development of Apparatus—The vacuum fusion analysis equipment described by Shields, Chipman, and Grant" was modified for the analysis of slags." This method depends upon the reduction of water in the slag to hydrogen, which is readily determined by the method used for hydrogen in steel. Preliminary experiments were made with a eu-tectic ferrosilicon melt as the reducing agent. Other experiments included the use of graphite and molybdenum crucibles. The ferrosilicon alloy bath was found to produce a thick coating on the furnace tube which could adsorb hydrogen. Graphite produced CO by the reduction of FeO, MnO, and SiO2 in such quantities that analysis for hydrogen was virtually impossible. Molybdenum, while giving a low blank value, could reduce the slag sufficiently to produce a volatile oxide which again was found to adsorb hydrogen. The arrangement finally adopted is shown in Fig. 1. The molybdenum sheet served as the induction-heated susceptor, and was separated from the escaping gases by alumina guide tubes. An outer jacket of alumina protected the quartz furnace tube, and alumina and quartz stools completed the assembly. The falling sample is shown wrapped in aluminum foil, 0.002 in. thickness, which acted as the reducing agent' This foil was careful'~ washed in acetone and an d and then dried in hot air before wrapping the weighed slag sample for charging into the apparatus. Investigation of the hydrogen content of the aluminum foil itself showed that a small quantity of hydrogen was released in vacuum, but had no relation to the weight of the aluminum charged. This quantity of hydrogen was

Jan 1, 1957

By Arthur Bell

(San Francisco Meeting, September, 1915) . PRIOR to 1908 the oil production in the State of California, had been almost entirely a heavy fuel, oil, with a high flash point, hut changed within a-short period to a large percentage of refining oil with a low flash, by reason of the coming in of the Santa Maria field, the Midway field, and the increased production of the Fullerton field. This is clearly shown in the following tabulation of California's production: Year Barrels . Below -20° Be, Above 20° Be,, Per Cent_ Per Cent. 1905 48,307,000 90 10 1910 77,698,000 SO 20 1912 90,075,000 6o 31 1914 10:3,600,000 47 53 The bringing in of these high percentage's of light oil with their dangerous low flash and the increasing demand for the refined products necessitated the devising of some cheap and efficient means of quickly separating the lighter elements either in the field or at the main distributing points; also it became necessary to remove the excessive percentage of water which many of the light oils carried in emulsion.

Jan 9, 1915

By Norman P. Goss

It is generally agreed that cold-working mechanically refines the grains into smaller fragments and with continued working these are oriented with certain crystallographic directions bearing a relation to the direction in which the metal is worked. Some of the energy expended on the metal during plastic deformation appears in the form of heat, but a very small portion remains in the metal as stored energy. The entropy, specific heat capacity, temperature at which recrystallization will just begin, density, ductility, elasticity, tensile strength, and resistance to corrosion are affected. These properties have been studied extensively and some of the changes in the physical properties due to cold-working were attributed to lattice distortion.l-8 The broadening of the Ka lines on the X-ray diffraction diagrams of plastically deformed metals is believed to indicate lattice distortion, and consequently the existence of internal stresses. The evidence supporting this theory rests solely upon the observed experimental fact that the diffraction lines are broadened and the Ka doublets are completely diffused. Elam9 has reviewed the matter of lattice distortion in relationship to the hardening of metals by plastic deformation. The X-ray diagrams of plastically deformed metals differ in general from annealed metals. The hardening of a metal was believed due to lattice distortion.9 The resolution of the doublet is lost when a metal is cold-worked and the Laue spots are elongated. At one time this elongation was thought to indicate the elastic bending of the crystal planes. However, more careful work showed that the asterism was due to new orientations developed within the fragmented grains during plastic deformation. Some theories attributed the hardening to fragmentation of the grains into smaller units. Jeffries and Archer,ll after carefully considering the problem of work-hardening from many angles, came to the conclusion that cold-working mechanically refines the grains into smaller crystal fragments, some of which at least differ in orientation from the parent grain. The increase in

Jan 1, 1940

By Norman P. Goss

It is generally agreed that cold-working mechanically refines the grains into smaller fragments and with continued working these are oriented with certain crystallographic directions bearing a relation to the direction in which the metal is worked. Some of the energy expended on the metal during plastic deformation appears in the form of heat, but a very small portion remains in the metal as stored energy. The entropy, specific heat capacity, temperature at which recrystallization will just begin, density, ductility, elasticity, tensile strength, and resistance to corrosion are affected. These properties have been studied extensively and some of the changes in the physical properties due to cold-working were attributed to lattice distortion.l-8 The broadening of the Ka lines on the X-ray diffraction diagrams of plastically deformed metals is believed to indicate lattice distortion, and consequently the existence of internal stresses. The evidence supporting this theory rests solely upon the observed experimental fact that the diffraction lines are broadened and the Ka doublets are completely diffused. Elam9 has reviewed the matter of lattice distortion in relationship to the hardening of metals by plastic deformation. The X-ray diagrams of plastically deformed metals differ in general from annealed metals. The hardening of a metal was believed due to lattice distortion.9 The resolution of the doublet is lost when a metal is cold-worked and the Laue spots are elongated. At one time this elongation was thought to indicate the elastic bending of the crystal planes. However, more careful work showed that the asterism was due to new orientations developed within the fragmented grains during plastic deformation. Some theories attributed the hardening to fragmentation of the grains into smaller units. Jeffries and Archer,ll after carefully considering the problem of work-hardening from many angles, came to the conclusion that cold-working mechanically refines the grains into smaller crystal fragments, some of which at least differ in orientation from the parent grain. The increase in

Jan 1, 1940

By R. Raring, W. J. Harris, J. A. Rinebolt

G. W. Geil (National Bureau of Standards, Washington, D. C.)—The authors state that the degree of accuracy realized in the experimental determination of a, is likely rather low. This inaccuracy is attributed to the difficulty in reading the load of the tension machine at the instant of fracture of the test bars. I believe there is another factor which may have added considerably to the inaccuracy in the determination of a,, namely, the determination of 8,. Fracture of a cylindrical tensile specimen of a ductile metal tested in tension at room temperature is generally initiated at the axis and rapidly propagates radially to the periphery of the necked section. During the propagation of the fracture, the metal at the rim of the minimum cross-section extends longitudinally and contracts radially. Thus values of 81, based on diameter measurements made after complete fracture of the specimens do not necessarily represent the strain at the initial fracture." Data obtained at the National Bureau of Standards with a 0.3 pct C steel in the condition as-quenched from 1575°F and tempered at 1000°F for 1 hr and tested in tension at room temperature indicated a considerable "rim effect" and as shown in Fig. 13, resulted in an apparent increase in Sf from 0.90 to 0.98. As the fracture strain of this steel is approximately equal to those of the steels reported by the authors, it seems probable that a similar "rim effect" may have added to the inaccuracies in the reported values of Si and accompanying values of El. R. Raring (authors' reply)—The authors are grateful to Mr. Geil for having called attention to a possible source of uncertainty in the determination of fracture stress, and they are in agreement with the principles upon which his discussion is based.

Jan 1, 1952

By Kurt Stock

The grades of spelter demanded by the consuming industries were not definitely established until the American Society for Testing Materials undertook to fix specifications, based on the varying percentages of the common impurities (lead, iron, and cadmium) as follows: Total, Not Leap, Iron, Cadmium, Over. Per Per Cent. Per Cent. Per Cent. Cent. A. High grade.................. 0.07 0.03 0.05 0.10 B. Intermediate................ 0.20 0.03 0.50 0.50 C. Brass special................ 0.75 0.04 0.75 1.20 D. Prime western............... 1.50 0.08 The question which grade was the best for certain purposes and why was left unanswered. The conservatism of the zinc-smelting industry and the unwillingness of the spelter-consuming industries to engage in research work prevented the full benefits being obtained that such standardization promised. The custom smelters, producing spelter in pigs or plates, found it impossible to adhere closely to the established limits on account of the variety of ores treated; and the smelters with long-established and known brands, or those manufacturing their metal into marketable products, like sheet zinc, did not have to abide by the newly established grades based on chemical percentages. Smelters engaged in the smelting of custom ores had occasional complaints about the quality of their metal, as some of the consumers, especially brassmakers and some galvanizers, used the rigid standards of the A. S. T. M. as a basis for obtaining redress from zinc smelters whenever some of their work was faulty. Indirectly, much good resulted from such complaints; for while the brassmakers and galvanizers, on the whole, did not know what was wrong, the metallurgists in charge of zinc smelters were induced to abandon their conservatism and study the influence of impurities in spelter from the point of view of the consumer. For some of us, spelter gradually ceased to be considered merely spelter; it

Jan 1, 1925

By R. L. Orr, O. D. Sherby, J. E. Dorn

Creep data for pure metals at temperatures above those at which rapid recovery occurs (above about 0.45 the melting temperature) are correlatable by means of the equations and These correlations were applied successfully to data for aluminum, iron, nickel, copper, zinc, platinum, gold, and lead as well as for simple alloys. For a given metal, AH is a constant about equal to the activation energy for self-diffusion. THE early recognition that creep is stimulated by thermal activation prompted numerous investigators', ' to apply the same laws that are valid for the viscous behavior of liquids to analyses of creep data. To a good first approximation these laws are summarized by the equation were i is the creep rate; T, the absolute temperature; R, the gas constant in cal per degree per mol; T, the applied stress; AH, the activation energy in cal per mol; S', a constant dependent on the entropy of activation, the frequency of activation, and the contribution of each activation to the strain; and B', a constant dependent upon the size of the flow unit that is activated. Although Eq. 1 describes the flow of viscous fluids very accurately, its application to the creep of solids has been disappointing. Two reasons for the failure of Eq. 1 for creep are now known: First, the decelerating creep rates during primary creep demand that the internal structures of the metals are changing and that these changes might be reflected by changes in one or more of the three creep parameters S', AH, and B'. Consequently when the conventional methods of evaluating these parameters are employed by comparing the secondary creep rates at a series of temperatures and at a series of stresses, the true effects of temperature and stress are masked because of simultaneous changes in one or more of the creep parameters. Second, as will be illustrated more fully later, three distinctly different types of investigations have shown that the stress term for high temperature creep enters the analysis as and not as t/T. This rather unexpected result points sharply to a significant fundamental difference between the mechanisms for the viscous behavior of fluids and the high temperature creep of metals. More recent extensive investigations",'4 on the creep of high purity aluminum and several of its dilute a solid solutions have shown that where E is the total creep strain; temperature compensated time = for a constant temperature test; t, is the initial stress in a constant load test or the constant true stress in a constant stress test;" and t is the duration of test. • Eq. 2 is valid for either constant stress or constant load tests; but the total creep curve is difierent (i.e. the function, f, is differentl for each test. The fundamental origin of the validity of Eq. 2 is thought to arise from some equivalence of substructures in constant load creep tests at equal values of 0 or E. Both X-ray and metallographic examination revealed that practically identical lattice distortions and subgrain sizes are obtained for the same creep strain under the same load over wide ranges of test temperature.' Furthermore the room temperature tensile properties following equal creep strains at different temperatures under constant loads were also identical, illustrating that identical substructures were indeed obtained.' " A second type of correlation was obtained by differentiating Eq. 2 with respect to time, giving For the secondary creep rate, denoted by i,, But Eq. 2 reveals that 0, is a function of a, alone because the secondary creep rate in a given constant load test is always reached at a fixed value E,". Therefore where is the function that was introduced a number of years ago by Zener and Hollomon." Eq. 4 is not only valid for creep but will permit correlations between constant load creep and tensile data where e, is the rate of tensile straining and (TC is the engineering ultimate tensile strength.

Jan 1, 1955

By AIME AIME

W. R. CHEDSEY first saw the light of day in Boulder, Colo., in 1887, and will celebrate his birthday on Feb. 11. Mining early attracted him, so he went to the Colorado School of Mines, from which he received his E.M. in 1908, and an honorary doctor's degree thirty years later. The next three years he spent at the University of Idaho, doing special work in mechanical and electrical engineering and serving as associate professor of mining engineering. Leaving Idaho in 1911 he went to Central America as chief engineer and general superintendent of the Central American Development Co. The next year he jumped several thousand miles to the north to become chief engineer and assistant general manager of the Alaska Exploration Co. But teaching was Chedsey's choice so he returned to his alma mater, serving on the faculty at Golden from 1913 to 1916. Then to Penn State where he was professor of mining for 21 years, until going to Rolla to become director of the Missouri School of Mines and Metallurgy in 1937.

Jan 1, 1940

By Henry G. Granger, Edward B. Treville

The Republic of Colombia is the northernmost country of South America. Its northern coast line exteilds from the frontier of Costa Rica to that of Venezuela, on the Caribbean Sea. On the west it fronts on the Pacific Ocean, along the Panama Isthmus, and down to Ecuador. It is bounded on the south by Ecuador, Peru and Brazil, which latter country with Venezuela form its boundaries on the east. Its area exceeds 500,000 square miles. It is deemed unnecessary to give here a map of the country. Fig. 1, a map of the department of Antioquia, studied in connection with a good modern general map of Colombia, will explain itself. Fig. 1 contains also some of the region of the Cauca valley, described in this paper. Access.—The interior of Colombia is reached through the ports of Sabanilla and Cartagena on the Caribbean Sea, each of which places is connected with the Magdalena river by a short narrow-gauge railroad, running respectively to Barranquilla and Calamar. From these points lines of river-steamers serve the ports of the upper Magdalena, which they reach in journeys of a week to ten days. After leaving the steamer, a short railroad journey, followed by a long and tedious mule-ride, reaches the cities of Bogota and Medellin. Quibdo, at the head of the navigation of the Atrato, and its most important town, is connected by steamer-service with Cartagena, by canoe-routes with the various districts of the Choco, and by mule-road, at present well-nigh impassable, with the heart of Antioquia. On the western coast the port of Tumaco is a starting-point for canoe- and mule-travel to the southern part of the department of Cauca, while Buenaventura is the port of the central section of the valley of the Cauca,

Jan 1, 1899

By C. Schlumberger

SINCE the beginning of .the year 1928 the senior authors and their associates have applied a series of procedures which makes possible the detailed study in situ of the formations traversed by a drill hole before the casing has been landed. They have given the name "electrical coring" to the ensemble of these processes, which now replace in a large measure the mechanical coring performed by the drillers, and permit the gathering of bottom-hole data hitherto unobtainable. Three years have elapsed since the technique and interpretation of these measurements emerged from the experimental stage and entered the field of industrial application on a large scale. The total length of drill holes so far surveyed by the authors and their associates, all over the world, amounts to several millions of feet. Practical and strongly built equipment has been evolved, which permits the examination in a short time of an open hole several thousand feet long. No comprehensive paper has yet been published discussing the essential principles of the processes applied and bringing into evidence their economic interest. This is the object of the present paper.1 Numerous examples of field work performed under varied geological conditions are given, constituting a concrete illustration of the services rendered by the new methods. The study in situ of the formations penetrated by a drill hole is based on the measurement of a given physical factor or parameter associated with these formations. Generally. the measurements are made syste-matically along the whole length of the open hole. The physical factors or parameters which are now utilized by us to this end are: (1) the resistivities of the rocks; (2) their porosity; (3) their electrical anisotropy; (4) their temperature; (5) the resistivity of the muds. In order to

Jan 1, 1932

By Douglas M. Smith

Silver-gold ratios were studied at the Tayoltita epithermal vein deposit using channel sample, channel sample line, stope, ore body, and vein sample populations. The ratios are highly variable among individual channel samples (25:1 to greater than 500: 1) with both high and low values randomly distributed within ore bodies and veins. Whole vein ratios for the 14 most important ore producing structures range from 44: 1 to 105:1, and show zonal distribution relative to two small granitic stocks, low values closest to the intrusives. The zoned nature of the deposit suggests that the stocks, apophyses of an underlying batholith of late Eocene age, were the heat engines which powered the hydrothermal system responsible for ore deposition.

Jan 1, 1980

By C. S. Samis, J. C. Mitchell

Sodion activity data have been obtained for the Na-A1 system for sodium concentrations in aluminum between NN, = 25 . 10-and 300 x 10'. This concentration intert-a2 encompasses those sodium concentrations nor1)zally encountered in aluminum reduction cell operation. The sodium activity data were measured by a two-phase equilibration of sodium between a lead and an aluminam rich phase. The Na-Pb system was emplojed as a reference for the determination of the actiz7itj 0.f sodium. The activity of sodiin in aluminuwz exhibits large positi2.e deviations frorn ideality and a strong dependence, on concentration below NN, = 100 x 1K6. The inteated data indicate that the activity of aluminium is equal to its mole fraction over the range of miscibility of the Na-A1 sgstem. The data on the Na-A1 binary have been combined with experimental data on the cryolite-A1 system at 1025°C to obtain the activities of Na F and AlF, in liquid cryolite oz2er the cornposition 1-ange encountered in aluminum cell operation. The results are in agreement with activities calculated from the NaF-AlF, phase diagram. ALUMINUM is produced commercially by the electrolytic reduction of aluminum oxide dissolved in molten cryolite. There is considerable controversy over the actual mechanism of the discharge processes, but sodium potentials in the systems appear to play an important role in the reduction mechanism. The metal-salt reaction involving NaF and aluminum to produce A1F3 and sodium is responsible for the presence of sodium in the aluminum metal phase. Additional sodium may be produced from the simultaneous deposition of sodium and aluminum at the cathode as a result of a cathodic overvoltage. runert' has suggested that sodium gas at atmospheric pressure would be the result of reaction between cryolite and aluminum at 1000°C. Subsequent investigations have shown that production of sodium at atmospheric pressure does not occur. These later investigations can be conveniently separated into two categories. The first involves sodium, aluminum, and cryolite, in which the sodium activity was measured. The second includes a lead phase for sodium activity measurement. Jander and errmann,' studied the reaction: at 1090°C in alumina crucibles under an atmosphere of dry, oxygen-free nitrogen. The equilibrium constant for the reaction was expressed in terms of concentration. Their results in Fig. 1 show an increase in sodium content of the aluminum with increasing NaF/A1F3 weight ratio. Pearson and waddington3 performed similar experiments at 1000°C. Their results are included in Fig. 1. Dewing and ollinshead have measured the sodium content of aluminum as a function of the NF/AF, ratio at 1025"C, Fig. 1, and ewin' measured the sodium content of the aluminum in a system involving the solid reactants NaF, cryolite, and liquid aluminum. This reaction is different from those discussed above. Two solid phases, NaF and Na3A1F6, and a liquid aluminum phase were present. The sodium concentration in the aluminum was determined by the temperature. Dewing's measurements covered the temperature range 679" to 896°C. Omo, Matsushima, and 1t02" investigated the equilibrium 6NaF ential thermal analysis. Stokes and Frank6 determined sodium activities by

Jan 1, 1970

By E. L. Jr. Spain

THE deposits described in this paper occur over much of Wayne County and in the southeast portion of Hardin County, Tennessee, and in the northeast and northwest portions of Mississippi and Alabama respec-tively. The presence of tripoli in this region has been known for some time and descriptions of various occurrences in Tennessee have been made by Jewell1 and Miser2, while Hilgard3, Lowe4 and Logan5 have treated the deposits that occur in the adjacent portions of Alabama and Mississippi, but there has not been a general survey of the entire field summarizing completely the geology of the deposits with respect to their origin and stratigraphic relationships. During 1934, while engaged in surveys of mineral resources through this region for the Tennessee Valley Authority, the writer collected data with this in mind, and has assembled them in this report. He is indebted to H. S. Rankin and N. A. Rose, of the Tennessee Valley Authority Geology Division, for field assistance.

Jan 1, 1936

By J. Wyn Prior

The seismic refraction technique is probably the most popular geophysical method of bedrock profiling in geotechnical site investigations but is somewhat restricted by the inherent assumptions in the method. This paper describes how Hales' method of profile interpretation is modified to overcome the assumptions of increasing velocity and layer thickness with depth when only first arrival data is available. A further expansion of Hales' method enables presentation of refraction data in a form whereby bedrock features, such as changes in velocity, relief and dip in particular, are more readily recognized. Characteristic curves of the more common bedrock features are presented as an aid to bedrock feature recognition.

Jan 1, 1979

By H. A. Schlesinger

Various studies have estimated that for the next few decades, about half of all new power plants will be nuclear. The other half will be fueled with coal. Pending legislation on air pollution control would require all new coal-fueled power plants to install stack gas scrubbers or other technology to reduce sulfur oxide (SO,) emissions. These regulations would require flue gas desulfurization (FGD) or other technology for SO, reduction even on lower sulfur western coals. Among the options for FGD are single or dual alkali throw away processes using lime or limestone as the major reagent. These processes are currently more economically attractive than recovery processes, such as magnesium oxide and Wellman- Lord, that produce a salable product such as sulfur or sulfuric acid. One of the major problem areas with the throw away processes is disposal of the thrown away solid wastes, primarily calcium sulfite (CaSO3) and calcium sulfate (CaS04). Coal ash also must be disposed of, even if SOx reduction is not required. This paper addresses the alternatives for handling and disposal of throw away lime, limestone, and dual alkali process solid wastes. Advantages, disadvantages, and the economics of various methods are discussed. Both large central station power plants (500-1000 MW capacity) and smaller industrial power plants (up to 100 MW capacity) are considered. High sulfur eastern coals (53% S) and lower sulfur (3 1% S) western coals are considered.

Jan 1, 1981

By Arne F. Westgren

X-ray analysis and single-crystal study have been utilized in recent years as a new means of following constitutional changes in alloys. If such transformations can be suppressed by rapid cooling, they can be followed at room temperature in a particularly convenient manner. In the following we shall consider changes in solubility and polymorphic transformations with particular reference to phenomena of the age-hardening type. Finally a thermodynamic viewpoint is developed for examining such transformations. Changes in Solubility 1. Determinations of solubility limits in the solid state which show decreasing solubility with falling temperature are made as follows: A series of alloys extending into the heterogeneous region is prepared and quenched fromas high a temperature as possible, whereupon their lattice parameters are determined. Then one or more alloys are quenched from temperatures at which they are heterogeneous and their lattice parameters likwwise determined. For the purpose of determining the parameter the apparatus shown in Fig. 1 has been very useful for it produces sharp films in a short time which can be accurately read. High-order reflections (interferences) from the object are recorded on a film which is placed exactly perpendicular to the X-ray beam. The specimen usually has the shape of a small round bar.l Fig. 2 shows a selection of such exposures of silver-rich Cu-Ag alloys, and Fig. 3 gives the measurements made from these films. Fig. 4 gives the solubility curve which results.2 This curve is shifted to lower concentrations than the curve that is obtained from metallographic or physical methods. The X-ray method unquestionably gives more reliable data

Jan 1, 1931

By John D. Verhoeven, Edward E. Hucke

An experimental technique has been developed for the measurement of the rate of electrotransport to a precision of 1 pct in the molten Bi-Sn system. Results are presented across the phase diagram from 30°C above the liquidus to 520°C. A phenomenological description is presented and the data on Bi-Sn are thereby converted to the effective charge, Analysis of the data indicates the true charge of the migrating tin species in bismuth to be +1.8 at 500°C. The data agree well with the recent work of Belashchmko. fieldintensity. The resistivity of the molten Bi-Sn system is also presented. WHEN an electric field is applied to a metal, a relatively large current is produced due to the ease with which electrons move within the metal. The electric field also produces a force on the ions which might cause them to migrate. Such a migration of metallic ions has been detected under certain conditions. This electromigration of the metallic ions will be referred to herein as electrotransport. The study of electrotransport in metallic systems has a rather long history dating back to the initial work of Gerardin1 in 1861. General reviews of electrotransport in liquid and solid metals have been published by Schwarz,2 Jost,3 Seith,4 and Heumann.5 In reviewing the literature it is apparent that the theoretical developments are not yet complete. The difficulty arises in describing the momentum transfer between the migrating ions and the electrons. In addition, there is a lack of good quantitative electrotransport data at high temperatures, especially in liquid metal systems. This work was undertaken to establish quantitative electrotransport data in a liquid metal system which might serve as a critical test of the theoretical developments. The Bi-Sn system was chosen for analysis, and the rate of electrotransport was determined as a function of temperature and composition. THEORETICAL CONSIDERATIONS If all of the atoms of a metal are considered to be positively charged due to the loss of electrons to the

Jan 1, 1963