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By G. K. Zaharlev

With a productive output growing at an annual rate of 8%, the Soviet mining industry should emerge as the world's leader in total mineral output during the 1980's. (The Soviet Union's share in the world's total mineral output in 1973 was estimated at 22 to 23%.) According to estimates by Soviet mining experts, the mineral potential of the Soviet Union will sustain the current 8% annual growth rate in the future.

Jan 12, 1974

By J. M. Snook, F. C. Langenberg

FOR a better understanding of the melting and refining processes, the oxygen content of the steel bath should be determined. The oxygen content influences many process and product variables such as the efficiency of alloy recoveries, the ingot structure (through reaction with carbon in the steel), certain reaction rates, cleanliness (formation of indigenous oxide inclusions), and mechanical properties. Many methods of sampling liquid steel for oxygen have been devised. These methods can be divided into two main groups: 1) taking samples directly in the furnace or ladle;'-'0 2) removing the metal from the furnace or ladle in a sampling spoon and pouring it into a mold, or drawing the metal from the spoon into a sample holder.11-l4 The advantages and disadvantages of the two general sampling methods are presented in Table I. The bomb-sampling technique described by Huff, Bailey, and Richards8 has been used by the Crucible Steel Co. in certain research projects where oxygen contents were needed. It was recognized that a localized boiling condition could result when the mold is introduced into the steel bath, although the work of Gilbert and Bailey9 seems to indicate that the carbon boil occurring in the bomb-sampler cavity has a negligible effect on the oxygen content. In order to confirm the reported negligible effect of a carbon boil, additional work was done with adaptations of the conventional bomb sampler. The methods used are shown in Fig. 1 and are as follows: 1) Type A: aluminum wire (0.125-in. diam) coil in cavity; steel cap over mouth 2) Type B: aluminum cup in cavity; aluminum cap over mouth, 3) Type C: aluminum cup in cavity; steel cap over mouth, 4) Type D: fine aluminum wire (0.013-in. diam) in cavity; steel cap over mouth. The amount of aluminum wire in the Type A and D samples varied from 0.8 to 1.2 pct of the sample weight. The aluminum cups averaged 2.0 pct of the sample weight; the latter were used to ensure that the steel contacting the walls of the bomb cavity was fully killed. Samples were taken from plain carbon heats made in open-hearth furnaces. This grade of steel before silicon additions is essentially an Fe-C alloy and the effects of other alloying elements on the oxygen activity can be neglected. The results of sampling with the bomb samplers is shown in Fig. 2 where the percent oxygen is plotted against the percent carbon on log-log paper. Spoon sample results on the same grade of steel where the sample was killed in the spoon are shown in Fig. 3. The oxygen contents were determined by the vacuum fusion method. A comparison of Figs. 2 and 3 shows that the oxygen concentrations obtained with the spoon-sampling method (metal killed in the spoon after slag removed

Jan 1, 1960

By J. Gordon Parr, L. P. Srivastava

DUWEZ1 has shown that pure titanium and pure zirconium transform martensitically during rapid cooling at temperatures about 30° and 15°C re spectively below their To temperatures. Holden et al.2 determined M, temperatures of Ti-Cu alloys by a metallographic technique applied to isothermally treated samples. Their results, superposed on the McQuillan3 version of the partial Ti-Cu diagram are shown in Fig. 1. Sources of metals were: Titanium: Iodide bar; Foote Mineral Co. Ltd. Zirconium: Iodide bar; Foote Mineral Co. LM. Copper: Spectrographic Standard; Johnson Matthey and Co. Ltd. Alloys were prepared by levitation melting under argon to the following nominal compositions:* 0.5, Quenching, at rates to about 8000°C per sec, was performed by cooling in a stream of helium (99.999 pct pure) a 3/64 in. cube of material previously heated by a tungsten coil in a system operating at. 10-5 mm Hg. Cooling rates below 200°C per sec w were obtained by controlling the current to the heater coil. The specimen was supported on a 32 gage Pt, Pt-Rh thermocouple attached through a DC amplifier to an Edin magnetic oscillograph (Model 8082) with a maximum chart speed of 250 mm per sec. Transformation temperatures were read off the oscillograph charts at the location of the beginning of the thermal arrest. The same specimen was quenched several times, and all runs were repeated on new samples. Regular calibrations of the oscillograph against a potentiometer were made between quenching experiments. The criterion of martensite formation was the effect of surface rumpling. Previously polished samples that showed a rumpled surface after transformation are assumed to have undergone martens itic transformation: transformations of a diffusion type produce no surface disturbance, Figs. 2 and 3. Electrochemical measurements were made in a cell described elsewhere4 whose electrodes were the martensitic and the diffusion-transformed materials in the following electrolytes:

Jan 1, 1962

By K. H. Heino

Two 200 T/da Lurgi Turbulent Layer fluid-bed roasters have been in operation at Canadian Electrolytic Zinc Limited since 1966. Zinc concentrate containing 52-54% Zn, 9-11% Fe,31-33% S is treated to produce calcine containing 60-62% Zn,10-12% Fe, .l-.3% S as sulphide and .8-1.2% S as sulphate. Each roaster train comprises a waste heat boiler, two cyclones in parallel and a two-field electrostatic precipitator. Distribution of calcine collected is 10-15 percent from bed overflow, 55-65 percent from boilers, 20-25 percent from cyclones and 2-6 percent from precipitators. A Monsanto designed contact plant produces acid at a rated capacity of 365 T/da (100% H2304 basis) from roaster gases diluted to 7.0-7.5% S02. The process steps are gas cleaning and cooling by weak acid scrubbing, acid mist removal in electrostatic precipitators, gas drying in 93.5-96.5% H2304, conversion of sulphur dioxide to sulphur trioxide in a four-pass converter containing vanadium pentoxide catalyst, and absorption of the sulphur trioxide in 98.1-98.3% H2S04. Product acid is 93.2% H2S04. Conversion efficiency is 97-98 percent and overall sulphur recovery from concentrate is 87-90 percent. The adjacent fertilizer plant has a capacity of 135 T/da of P205. The products are 54 percent phosphoric acid, run-of-pile triple superphosphate, and diammonium phosphate. The plant is of Ugine-Kuhlman design and consists of an air-cooled multiple tank reactor, a tilting pan filter, and a forced circultation vacuum evaporator. Triple superphosphate is made on a continuous belt and partially cured in a rotary dryer. Diammonium phosphate is produced by ammoniating phosphoric acid in a single stage reactor. The slurry of ammonium phosphate is granulated in a blunger and dried.

Jan 1, 1970

By Charles Maier

IT has long been supposed that when crystalline materials are com-minuted the energy used in the production of increasingly smaller grain sizes is not entirely dissipated as heat but that a certain portion is "stored" as a part of the internal energy of the material. This portion usually has been called the "surface energy" of the particles. The practical interest of the Bureau of Mines in this subject in connection with the energy requirements of crushing processes has led to the author's attempt to measure the "stored" energy in finely divided calcite by heat-of-solution methods1. The experiments on calcite showed that "storage" of energy could not be proved for this material, because fine grinding caused a lack of chem-ical homogeneity evidenced by loss of carbon dioxide and subsequent adsorption of water on the surfaces of the calcite particles. When thermochemical correction was made for composition changes the cor-rected heat of solution was less for fine material than for coarse. Con-tinuation of the experimental work into the problem of comparing work and heat in the deformation of metallic crystals, where the calorimetric difficulties were less, showed, however, that in the case of copper and aluminum a real discrepancy between work and heat could be shown. similar results had previously been obtained by Farren and Taylor2 and Hort3 and more or less simultaneously with the author's work by

Jan 1, 1936

By Charles Maier

PART I DENSITY AND ENERGY CHANGES IN COLD-WORKED COPPER IT has long been supposed that when crystalline materials are com-minuted the energy used in the production of increasingly smaller grain sizes is not entirely dissipated as heat but that a certain portion is "stored" as a part of the internal energy of the material. This portion usually has been called the "surface energy" of the particles. The practical interest of the Bureau of Mines in this subject in connection with the energy requirements of crushing processes has led' to the author's attempt to measure the "stored" energy in finely divided calcite by heat-of-solution methods1. The experiments on calcite showed that "storage" of energy could not be proved for this material, because fine grinding caused a lack of chem-ical homogeneity evidenced by loss of carbon dioxide and subsequent adsorption of water on the surfaces of the calcite particles. When thermochemical correction was made for composition changes the cor-rected heat of solution was less for fine material than for coarse. Con-tinuation of the experimental work into the problem of comparing work and heat in the deformation of metallic crystals, where the calorimetric difficulties were less, showed, however, that in the case of copper and aluminum a real discrepancy between work and heat could be shown. Similar results had previously been obtained by Farren and Taylor2 and Hort3 and more or less simultaneously with the author's work by

Jan 1, 1936

By William R. Webster

I have continued the investigation of the Pottstown Iron Com pany's basic Bessemer keel plates on the line referred to in my paper of last October (Trans., xxi., 766)) and have added a study of the hardening effects of sulphur, which were not taken into account at that time. The results are so encouraging that I now give them in full. For some months we have graded all the steel at these works by the table given in my former paper, and checked the grading by the forging-tests as described in the paper of Mr. Joseph Hartshorne, read at the same meeting (Trans., xxi., 748). The steel thus graded was bloomed for the plate orders. Then one slab was rolled into a plate for the order, and a tension-test was made of this plate. By the result of this tension-test we were guided in rolling the balance of the heat. Out of several hundred heats graded in this manner, 95 per cent. met the requirements of the orders in every respect, and were accepted; but these results will no doubt be improved upon, when the influence of sulphur is also considered.. The hardening effect of sulphur seems to be about 500 pounds per each .01 per cent. of increase. In the table accompanying the pres ent paper, the ultimate strength with .06.5 per cent. sulphur agrees with the old table where sulphur was not considered; that is, for all steels with less than .065 per cent. sulphur we now get lower re sults, and for those with more sulphur, higher results. Making this allowance for sulphur, the assumed ultimate strength of a 3/8-inch plate of pure iron is reduced from 38,000 pounds per square inch to 34,750 pounds. With this as a basis, I have constructed my new table, giving each of the elements, carbon, phosphorus and manganese the same hardening effect as before, to wit : Carbon is credited with a constant effect of 800 pounds per each, 0.01 per cent. Phosphorus shows greater effect in high-carbon than in low-carbon steels. For 0.07 and 0.08 C, it has about the same effect as carbon, that is, 800 pounds for each .01 P. This increases to 1500 pounds per .01 P in 0.15 C steel, or nearly twice the effect of carbon. This

Jan 1, 1894

By J. C. Draper

Duquesne Light Co.'s Portal No. 3 mine, in the Warwick group of mines in Southwestern Pennsylvania, was started in June 1965 with battery- powered tractor-trailer face haulage. The area as- signed to Portal No. 3 encompasses over 8000 acres of coal and will be developed by driving a set of main entries through the center of the tract in roughly a westerly direction, and sub mains on a 45º deflection angle in roughly a northerly direction (Figs 1 & 2). In the original planning these sub mains were to be at a 90º angle with the mains, but difficult roof conditions necessitated a change in plans. The entries and crosscuts are driven 18 ft wide in the normal Sewickley seam which varies between 46 and 56 in. high. The mine bottom is a strong shale and in average, cool or dry outside conditions stands up well for rubber-tired haulage equipment, but when the outside conditions are hot and humid, the bottom becomes soft and muddy. This condition lessens as the mine faces are advanced further from the portals because the condensation will then take place principally on the surfaces of intake entries outby the working areas. To aid the situation, an air cooling system was installed and is used as conditions dictate.

Jan 7, 1968

1876, PROF. RICHARD AKERMAN Stockholm, Sweden. 1913. DR. FRANK DAWSON ADAMS Montreal, Canada. 1909. PROP. RICHARD BECK Freiberg, Germany. 1905. ANDREW CARNEGIE New York, N. Y. 1906. DR. JAMES DOUGLAS New York, N. Y. 1888. PROF. HATON DE LA GOUPILLIERE Paris, France. 1966. SIR ROBERT A. HADFIELD London, England. 1888. PROF. HANS HOEFER Leoben, Austria. 1917. HERBERT C. HOOVER San Francisco, Cal. 1915.. JAMES FURMAN KEMP NEW York, N. Y. 1905. PROF. HENRI LOUIS LE CHATELIER Paris, France. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1909. ALEXANDRE POURCEL Paris, France. 1911. DR. ROSSITER W. RAYMOND New York, N. Y. 1911. PROF. ROBERT H. RICHARDS Boston, Mass. 1909. DR. ING. H. C. EMIL SCHROEDTER Dusseldorf, Germany., 1906. JOHN E. STEAD Middlesbrough, England. 1902. PROF. DIMITRY CONSTANTIN TSCHERNOFF Petrograd, Russia. 1910. PROF. TSUNASHIRO WADA Tokyo, Japan. 1907. CHARLES D. WALCOTT Washington, D. C.

Jan 1, 1917

Albin, B. R. Billings, Mont. 28 Amster, Nathan L 25 Broad St., New York, N. Y. '28 Bache, Jules S. 42 Broadway, New York, N. Y. 28 Barrett, C. P. 5338 Harper Ave., Chicago, 111. '28 Baum, Frank G., Cons. Hydro-Electric Engr Cassel, Shasta Co., Cal. '28 Bayless, William S. Russ Bldg., San Francisco, Cal. '28 Bean, Louis H.60 E. 42nd St., New York, N. Y. '28 Beatty, Roes J. 1105 First National Bank Bldg., Chicago, Ill. '28 Benwell, Oswald F. Hold Mags. '28 Beymer, Albert S., V.P., Keystone National Bank Pittsburgh, Pa. '28 Blumenthal, Hugo 44 Pine St., New York, N. Y. '28 Boettcher, Charles Ideal Cement Bldg., Denver, Colo. '28 Bowlus, Thomas H. Iola, Kan. '28 Brown, Colvin B. Chamber of Commerce, Washington, D. C. '28 Bart, Maxwell Struthers Southern Pines, N. C. '28

Jan 1, 1932

Albin, B. R Billings, Mont. '28 Amster, Nathan L 25 Broad St., New York, N. Y. '28 Bache, Jules S. 42 Broadway, New York, N. Y. '28 Barrett C. P. 5338 Harper Ave., Chicago, Ill. '28 Baum, Frank G., Cons. Hydro-Electric Engr Cassel, Shasta Co., Cal. '28 Bayless, William S. Russ Bldg., San Francisco, Cal. '28 Bean, Louis H. 60 E. 42nd St., New York, N. Y. '28 Beatty, Ross J. Room 604, 6 N. Clark St., Chicago, Ill. '28 Benwell, Oswald F. Hold Mags. '28 Beymer, Albert S., V.-P., Keystone National BankPittsburgh, Pa. '28 Blumenthal, Hugo. 44 Pine St., New York, N. Y. '28 Boettcher, Charles Ideal Cement Bldg., Denver, Colo. '28 Bowlus. Thomas H. Iola, Ken. '28 Brown, Colvin B. Chamber of Commerce Washington, D. C. '28 Burt, Maxwell Struthers Southern Pines, N. C. '28

Jan 1, 1932

[A AALSETH Earl P (M 51) Consult Geol Engr 2019 Eldorado Dr, Billings, Mont ABADIE Henry G (M 43) Asst to. Supt of Oper Long Beach Oil Dev Co 925 Harbor Plaza, Long Beach 2, Calif. ABBET Waldo (A 56) Asst Diet Oper Supt Sun Oil Co P 0 Box 66, Stowelt, Tex ABBOTT Clifton T (A 60) Apartado 677, Maracaibo, Venezuela ABBOTT Fred E Jr (M 59) Abqaiq Diet Mgr Arabian American Oil Co Dhahran, Saudi Arabia ABBOTT J L (M 56) Partner Pritchard & Abbott 1010 Ft Worth Natl Bk Bldg, Fort Worth 2, Tex ABBOTT Richard H (J 51) Partner Abbott & Howard 422 W Hermosa, San Antonio 12, Tex ABBOTT William G (M 50) Div Mgr Rice Engrg &. Operating Inc Box 1142, Hobbs, N. M. ABDERHALDEN Ronald R (J 59) Prod Engr Continental Oil Co Box 100, Carml, 111]

Jan 1, 1961

By C. G. Goetzel

Until recently porous bronzes have found many applications for self-lubricating bearings in the automotive, electrical, household appliance and general machine industries. The bulk of an annual production of several million pounds of copper powder had gone into the manufacture of these articles, of which by now more than a billion are in service. However, the war has brought severe curtailment of these bearings because of the scarcity of the two main constituents, copper and tin. The development of substitute materials of equal or superior properties has led to a large-scale replacement by products made from iron powder. In spite of the diminished interest in powdered copper-tin alloys caused by this trend, it was believed worth while to investigate some mechanical properties of these materials as a reference base for substitutes. In addition, experiments using the hot-press method were incorporated to investigate possibilities of saving vital equipment or opening new fields of applications. It must be assumed that by this time the powder metallurgy process of making porous bronzes, a development that found its first industrial applications more than 10 years ago, is well known in engineering. The patent literature and bibliography is volu- minous, most publications referring to porous, self-lubricating bronzes, containing about 10 per cent tin and I to 5 per cent graphite, with porosities in the range of 25 to 35 per cent.l-7 The excellent antifriction properties of these bearings, caused by the uniform impregnation with oil, are dependent on the interconnection of the pores and the uniform distribution of the graphite inclusions. The sintering mechanism of porous bronze, with its structural changes during the transformation of the metal powder into the sintered bearing has been shown in colored photomicrographs by Hall.* Diffusion between copper and tin was found to begin within one minute, when tin-rich transitory phases were formed. After 25 min. a homogeneous matrix of alpha was reached for an alloy containing 9.5 per cent tin and 6 per cent graphite. Price, Williams and Garrand,9 studying certain metal powder combinations in which sintering is accompanied by the cementing action of a liquid phase, including a 90-10 bronze sintered at 925°C., have found that if the treatment is carried out within the liquidus and solidus temperature range of the system, a peculiar process of alternate solution and precipitation occurs. The particles of the major solid constituent are dissolved in the minor liquid phase, but thereafter are reprecipi-tated on certain nuclei, which develop into large grains, usually rounded.

Jan 1, 1945

By S. W. Zehr, G. S. Murty, W. A. Backofen

AN observation by Squires, Weiner, and phillipsl has stimulated interest in a mechanism of deformation at high temperature (above -0.5 of the absolute melting point) that is not usually thought to be involved in the creep of metals. They found precipitate-free or "denuded" zones along grain boundaries normal to the stress axis in tensile specimens of a hydrided Mg-1/2 wt pct Zr alloy after slow straining at 450° and 500°C. Their suggestion that the zones were a result of directional diffusion of magnesium atoms was supported with calculations from Harris and Jones2 which also tended to identify the process as Nabarro-Herring (N-H) creep3,4—a process that is characterized by Newtonian viscosity, with stress (o) directly proportional to strain rate (C), and one that proceeds by lattice diffusion. Material transport by diffusion along grain boundaries is an alternative basis for Newtonian viscosity, as demonstrated by Coble,5 and is favored over N-H creep for fine grain size and lower temperature.6 In either case, the strain rate sensitivity of flow stress, defined as m = d log o/d log E (which commonly appears in the empirical a = KEW), is unity. The experiments to be described here gave metallo-graphic indications of diffusional creep which were no less clear than those just cited, but the associated m (as measured by the method of Ref. 7) was much more like that of a Bingham material. For true Bingham behavior, (a — ao) E, where oo is an initial yield stress. Therefore, even if flow after yielding should occur by diffusional transport, m must increase from 0 as < is raised to reach unity only in the limit as One result is that the resistance to tensile necking conferred by Newtonian viscosity is lost, which would become increasingly apparent through the formation of more sharply defined necks as 6 is lowered. That trend appeared in these experiments. Most of the work was done on an extremely finegrained alloy of magnesium with -6 wt pct Zn and ½ wt pct Zr (Mg ZK60); the initial mean-intercept grain diameter, L, was 0.55 µ. Shown in Fig. l(a) is a germanium-shadowed carbon replica of the surface of a specimen that was coated with silicone oil,* heated to 270°C under a helium atmosphere, and then stretched locally -200 pct at an initial E = 3.3 x 10-5 sec-1. Under

Jan 1, 1969

By H. D. Hibbard

At the beginning of a Henry M. Howe lecture it seems fitting to refer to Howe&apos;s great contributions to steel metallurgy, and particularly to the literature thereof. Most of my predecessors in this role have been able, from their association with him, to give direct testimony as to his great services; but although connected with him for years in a business way, I am less familiar with what might be called his academic side, except as it is embodied in his utterances, written and oral. Howe was adept in his genial way in extracting information in any line which, at the time, was of interest to him. In a technical lecture one expects as a rule new knowledge-—something about recent advances relating to the subject. On this occasion, however, I will ask you to go back with me to the primary department of steel lore, as the title of my lecture shows, to review the more fundamental features in that field for the purpose of seeking some gaps which we can fill and so give the subject renewed interest. In thus going back one must inevitably repeat many familiar facts, but that seems to be necessary in order to reach a clear understanding of the unrecorded matters. The full interpretation of a steel analysis is at present unattainable, though much progress toward that end has been made. The ultimate analysis, giving the percentages of the five commonly determined elements, does indeed usually give a fair idea of what the steel is, and is ordinarily enough, with knowledge of its history and physical condition, to enable it to be assigned to some purpose or use for which it is reasonably suitable. Rut discrepancies arise. Every maker and every User of steel knows, from at least occasional examples in his own experience, that the ultimate analysis is insufficient by itself to enable one to tell positively, from its interpretation, either the mechanical properties of the steel or its adaptability to the purpose for which it was made. Further, if, while having the specified composition, it is abnormal or unsatisfactory, why it is so. Good, bad and indifferent steels may have substantially the same ultimate analysis.

Jan 1, 1928

By W. White, C. S. Barrett, R. M. Mueller

THIS communication reports film-recorded low-energy (-100 kev) proton blocking patterns&apos;-3 for hcp and wurtzite crystals. In particular the sequence of relative line intensities* (corresponding to planar blocking) of common hcp metals is compared with those of the wurtzite semiconductors CdS and CdSe. The results show that the sequence is characteristic of structure. For closely similar structures such as those of CdS and CdSe, differences of line intensity attributable to the difference in atomic number, 2, of the scattering centers may also be seen. The apparatus and techniques used in this work were identical with those reported previously in a study of cubic systems.3 All metals were given standard metal-lographic etches, and the semiconductors cleaved, immediately prior to introduction to the vacuum system. Fig. 1 shows the unit cell of the wurtzite structure, and the geometry used to obtain the [1120] and [0001] patterns of Fig. 2. The axial ratio, c/a, for all ma- terials of Fig. 2 is close to 1.63. The patterns are then directly comparable in linear dimensions inasmuch as they have been reproduced at the same overall magnification of the patterns. (Overall magnification is proportional to the product of film-to-target distance and printing magnification. Thus the 1/6-in.-diam beam passage hole in the center of the film need not appear of uniform size in the prints.) The patterns for a given orientation, though similar

Jan 1, 1970

By M. B. Bever, A. K. Jena

Equations for the heat effects of additions of mixtures of multicomponent phases to a solution have been derived in terms of the enthalpy interaction coefficients. By these equations and the measured composition dependence of the heat effects on addition of mixtures of Ag-Cd solid solutions and elemental gold to liquid tin-rich solutions, values of the enthalpy in-teraction coefficients in tin-rich solutions at 541°K have been obtained. Analysis of these results in terms of the regular solution theory and the quasichemical theory suggests that near the melting point of the solvent association in the solution becomes important. SEVERAL recent papers have discussed the nature of dilute solutions on the basis of measured enthalpy interaction coefficients. l-3 These coefficients contribute to the understanding of the constitution of solutions and can be used for the evaluation of thermo-dynamic data of multicomponent systems. Their experimental determination, however, is laborious. This communication reports values of the enthalpy interaction coefficients of silver, cadmium, and gold in liquid tin-rich solutions obtained from the measured heat effects of additions of mixtures of Ag-Cd solid solutions and elemental gold to liquid tin-rich solutions. These measurements were made in the course of the determination of the heats of formation of Ag-Cd solid solutions reported in a concurrent publication.4 THE HEAT EFFECT OF AN ADDITION TO A SOLVENT This analysis is concerned with the addition of a mixture of multicomponent phases from the temperature To to a solvent of known composition at temperature T. If Nmixture << Nsolvent, where N designates the gram-atoms involved, the heat effect per g-atom of mixture added can be expressed as (HT - HT )i = difference in heat contents of component element i in the mixture at T and To Q = heat effect on solution of the mixture at temperature T Also1 Q = S Xi [2] where ?Hi ,T,x = relative partial enthalpy per g-atom of i in solution at temperature T and composition of the solution x x = average of the atom fractions of the added material in solution before and after the addition The relative partial enthalpy ?Hi per g-atom of an element i in a dilute solution composed of a solvent 1 and the solutes j = 2, ... m is related to the interaction coefficients by the following equation5 ?Hi - ?Hi-?Hi,x1-1 + S n1ixj+ . . . +S...S...S nrixn2... Xnji...Xnmm+... [3] vhere Xj = atom fraction of solute j in the solution nri = the rth order enthalpy interaction coefficients, which can also be represented by the more general designation5 L(i)n2,n3...nm and nj may have any positive integral value or zero. For identification of various rth order interaction coefficients, nri is written as nn2i2,...nij,...nmm. Eqs. [1], [2], and [3] combine to give the following general equation for the heat effect on addition of a small quantity of a mixture to a large quantity of a dilute solution n = _?ga ?Ha,To + ? Xi(HT - HT o)i a. i + ?xi?Hi,X,i?1 + ??xnjixj + . . . + ???. . .?. . .?xinrix2n2. . . xnji. . . xnmm+ . . . [4] The first term on the right-hand side of this equation is the heat of decomposition at the addition temperature of the phases present in the mixture, the second term is the heat required to raise the temperature of

Jan 1, 1970

By E. Lifshin, R. E. Hanneman

QUANTITATIVE applications of the electron micro-beam probe frequently involve the evaluation of complex mathematical expressions and/or the analysis of large amounts of experimental data. The purpose of this communication is to describe briefly a versatile and useful computer program system that is applicable to analyze rapidly a wide variety of practical microprobe problems. This system consists of a group of ten FORTRAN programs that can be stored on tape, cards, or in the memory disc of the computer. These programs, or links, can be run individually or in any prespecified sequence without interrupting the operation of the computer or without destroying information which is being transfered from one link to another. For the program system described here a GE-235 computer with disc storage was used, so that the DCHAIN method of program linking was employed. Included in the library are programs to: 1) initiate analysis of a new set of data and transfer control between all other programs in any predetermined manner; 2) generate theoretical calibration curves of composition vs relative intensity; 3) generate empirical deviation parameters from least-square fits of experimental calibration data from standards of known composition; 4) convert raw X-ray data to corrected composition; 5) determine inter diffusion coefficients by Matano analysis of con centrat ion -distance data on a uniaxial diffusion couple; 6) determine activation energies and frequency factors of temperature-activated processes such as diffusion; and 7) generate calibration curves for determination of the thickness of thin films using microanalysis. A detailed description of these computer programs and their underlying principles is available on request from the authors."&apos; The first program to generate theoretical calibration curves of corrected relative intensities vs composition uses the Poole and Thomas atomic number correction&apos; and the Philibert absorption factor&apos; with a voltage-dependent mass absorption coefficient for electrons in the alloy. A modified Castaing fluores- cence correction is also used which includes the effects of both Ka and KO radiation and over voltage.&apos; Once the theoretical curves have been calculated in 1 wt pct intervals, these results are least-squares fit to obtain Ziebold deviation parameters&apos; which are stored in COMMON in the computer memory. The net discrepancies between the original theoretical calibration curve and the regenerated curve using the Ziebold parameter are computed. Although this link is explicitly written for K-K fluorescent interactions, it can be applied to K-L, L-K, and L-L interactions as previously disc~ssed."~ Similar programs have also been written to utilize the Wittry fluorescence correction, Birks combined corrections, and various other corrections.&apos; These modified programs have proved to be quite useful for quantitative comparisons of the results of the various theories. The program for conversion of raw X-ray data to corrected composition includes corrections for drift, backround, and instrumental dead time. The corrected intensities are converted to composition by use of the Ziebold equation"2 and parameter obtained from the program system. The results can be obtained for either atom or weight fractions. In addition to accurately computing interdiffusion coefficients the Matano analysis program calculates least-square smoothed values of concentration, concentration gradient, and curvature for each point on the raw input concentration profile. In order to obtain high accuracies a unique method of performing a least-square polynomial fit to incrementally advancing profile segments which overlap is used.&apos; This program has been successfully modified for use in ternary diffusion problems3 and can readily be modified to handle analysis of diffusion profiles which include phase boundary discontinuities. This link is generally applicable to analysis of interdiffusion data obtained by other techniques as well as by the microprobe. The primary function of the next program is to least-squares fit experimental diffusion data to the normal Arrhenius function: D = Doexp(-Q/RT), to obtain values of Do and Q. In addition the probable error and one, two, and three u statistical confidence limits of DO, Q, and log D are evaluated. This program is also directly useful for analysis of any other simple temperature-activated processes including conductivity, and certain deformation and chemical processes. The program to generate calibration curves for film-thickness determination using the microprobe is based on a numerical integration of the equation derived by Cockett and ~avis.&apos; Values of film thickness obtained by this program for copper on various substrates are in good agreement with measurements made by other techniques. Versions of the above program system have been prepared for use with or without a remote teletype connection to the computer for processing on either a real-time or time-share basis. The instrumentation coupling a microprobe to a teletype for automatic data collection and analysis by the presently described program system has been reported elsewhere by the authors.&apos; If teletype equipment is not used to communicate with the computer, standard methods of card reading and tape reading can be used. In either

Jan 1, 1967

By J. B. Seabrook

The accompanying Fig 1 is a graphical scheme of intermediate accuracy for expediting interconversions of mol, weight, and volume percents. This chart consists of a family of curves of mol or atomic or volume percent plotted against weight percent, each curve in the family providing for a certain ratio of molecular or atomic weights or densities. Thus, the whole range of variations is presented in a very familiar format, and the conversion is effected simply by choosing the proper curve and reading off the required values. An entire series of conversions for a given binary system can be found by following the appropriate curve. It is interesting to examine the analytical geometry of the plots. The curves, which must fit into a square and all join at the 0 and 100 pet points, may be shown to be hyperbolas with their centers on the extension of the diagonal of the square which they intersect. Multiplying out the expression x A atomic fraction of A = y = ------ where x is the weight fraction of A, and A and B are atomic weights, we get xy+A/By- A/Bxy=x Upon rotating and translating axes and avoiding imaginaries, it is found that the angle of rotation is —45°, the origin moves upv2/2 units andv2/2(A/B+1/A/B-1) units to the right, and the standard form is Thus the curves are equilateral hyperbolas, their centers are units away from their intersection with

Jan 1, 1950

By G. G. Hancock, H. H. Johnson

Hydrogen gas at atmospheric pressure is shown to cause substantial embrittlement in a martettsitic high-stretzgth steel. Subcritical crack growth is observed at very lom stresses and with high growth rates. It is suggested that an adsorbed layer of hydrogen atoms at the crack-tip surface provides the damaging hydrogen. Oxygen in small quantity, as little as O.7 pct by volume, is shown to eliminate subcritical crack growth in gas environments caused by hydrogen or water vapor. However, dissolved oxygen in water has little or no influence upon crack-growth rates. Oxygen-stopped cracks may be restarted by water, or by hydvogen or water vapor if oxygen is removed from the environment. These observations are interpreted in terms of preferential adsorption of oxygen at the crack tip and the formation of an oxide barrier. RECENT investigations1-3 have demonstrated that environmental factors are frequently responsible for delayed failure in martensitic high-strength steels. The environment causes crack initiation from preexisting cracklike flaws at unexpectedly low stresses, often far below the uniaxial yield strength. The crack then propagates at a rate controlled by the environment and the crack-tip stress-field intensity; during this period crack propagation will cease if either the stress or the aggressive environment is removed, and this may be considered a definition of subcritical crack growth. Fracture occurs when the crack has grown to a critical length, such that the fracture toughness of the steel is exceeded. Several liquids are known to cause delayed failure, but water and water vapor are the most severely damaging of the environments investigated to date.&apos;-3 It has been suggested that hydrogen produced during corrosion reactions may be the actual embrittling agent2 The severe embrittlement caused by water vapor inevitably raises the question as to whether other gas environments are damaging. Previous work4&apos;5 has demonstrated that high-pressure hydrogen (2250 psi or greater) is an effective embrittling medium, as measured by such criteria as reduction in area, notch tensile strength, and time to failure. Moreover, the embrittlement was eliminated by the addition of small quantities of air or oxygen to the high-pressure hydrogen, but it was not influenced by additions of nitrogen or argon.4 In the present study attention is focused upon gas environments at atmospheric pressure, in particular hydrogen and oxygen. The influence of these constituents upon the initiation and growth of a crack from a pre-existing cracklike flaw in a high-strength steel was determined directly by the electric-potential method of monitoring crack growth. MATERIALS AND PROCEDURE The H-11 steel was supplied by the U.S. Naval Research Laboratory as 3 by 12 by 0.065 in. sheet specimens with 1-in. transverse center slots. The slot tips were finished by Elox machining to a radius of 0.001 in. or less. The yield strength was 230,000 psi; chemical composition and heat-treatment schedule are given in Table I. The experimental apparatus, precracking procedure, and incremental loading sequence have been described previously.3 In the only significant change, precracking was sometimes carried out by a hydrogen embrittlement and baking technique. All experiments were conducted at room temperature; the hydrogen gas environment was purified by a commercial palladium purifier. Crack initiation and propagation were followed by the electric-potential method,&apos;-3 using a calibration that has been recently dicussed. Stress-field intensities at the crack tip were computed by the conventional Irwin frmula; the plasticity correction was negligible and therefore not included. EXPERIMENTAL RESULTS A striking brittleness associated with molecular hydrogen at atmospheric pressure is demonstrated by the data in Table I1 and Fig. 1, which indicate that subcritical cracks in hydrogen initiate at lower stress-field intensities and propagate more rapidly than in fully humid argon. Ki and Kf are the crack-tip stress-field intensities at initiation and termination of subcritical crack growth, respectively. Termination, of course, corresponds to fracture. In both hydrogen and humid argon Ki is less than Kf

Jan 1, 1967