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By C. H. Li, R. D. Carnahan, R. J. Stokes, T. L. Johnston

When silver chloride deforms by pencil glide at temperatures of 26ºand 72°C, grain size has no effect upon the proportional limit and the material necks down to a knife edge under tension. At -196ºC, deformation takes place on fewer slip systems to produce straight slip traces, the flow stress becomes sensitive to grain size and fracture occurs by cleavage from an intergranular source without any reduction in area. THERE are significant differences between the appearance of the slip bands formed in silver chloride and in the alkali halides at room temperature. The bands in sodium chloride, e.g., are fine and geometrically straight, whereas in silver chloride they are coarse and wavy.' Such differences in the slip behavior prompted us to inquire what the effects of grain boundaries might be on the mechanical properties of these solids. As an introduction to a general study of ionic poly-crystal behavior, we have investigated the effect of grain size on the stress-strain relationships in silver chloride at different temperatures. We have chosen silver chloride chiefly because polycrystals can be easily prepared free from cracks and macroscopic voids by conventional techniques. Moreover, as we shall see, the slip behavior can be readily modified by changing the temperature. It will be shown that the effect of grain size on the yield stress of silver chloride is strikingly dependent upon the temperature of deformation and that this temperature effect comes about through a change in the number of slip systems which operate at the onset of plastic flow. EXPERIMENTAL PROCEDURES Polycrystalline tensile specimens were made by recrystallizing cold-rolled AgCl sheet. Thirty-gram quantities of AR grade silver chloride powder were melted in a low heat capacity furnace, cast into cylindrical forms 3/4 in. in dim and approximately 1 in. in length and then extruded with a 16:l reduction ratio into rods 3/16 in. in dim. Extrusion temperatures were varied from room temperature to 350°C. In order to impart various degrees of cold'work to the extruded rod. All extrusions were then cross rolled to sheet 0.040 in. in thickness at room temperature and machined to form tensile specimens having a gage length of 0.750 in. with a width of either 0.250 or 0.145 in.* Annealing was carried out in an air oven at 200°C for periods up to 20 hr. specimens having average grain diameters ranging from 0.024 to 0.40 mm were prepared by varying the extrusion temperature and annealing time in the conventional manner. To obtain specimens with grain sizes larger than 0.40mm, lightly deformed thin prisims of silver chloride single crystals (supplied by Harshaw Chemical Co.) were recrystallized. Grain size determinations were made by an intercept method and revealed that the grains were equi-axed. Laue back-reflection X-ray patterns showed little tendency to form a preferred orientation texture. Specimens which were to be used for the slip band studies were polished by immersion in fresh boiling concentrated NH,OH for 60 sec. They were then etch polished for 10 sec on each side by hand lapping on a stationary velveteen lap wetted with a dilute Hypo solution (5 g of Kodak Acid Fixer in 100 cc H20). Finally the specimens were rinsed in warm water and alcohol, blown dry and carefully mounted in the tensile machine for testing. Tensile tests were performed at three temperatures, namely, 26º, -72º, and -196°C. A screw-driven hard tensile machine was used at a constant strain rate of 0.006 in. per in. per min. Loads were determined with a light- proof ring fitted with A-18 strain gages and extensions were measured with a 0.0001 in. dial gage. Constant level baths of alcohol with dry ice and liquid nitrogen were used to maintain the two lower test temperatures. EXPERIMENTAL RESULTS Reproducibility—In view of the light sensitivity and reactive nature of silver chloride, it was necessary to determine whether reproducibility depended upon either exposure to light or to the condition of the surface. However, during the course of the work it became clear that variation of laboratory lighting

Jan 1, 1962

By M. Bevis, A. F. Acton, P. C. Rowlands

Defor~nation twinning and transformation twinning modes most likely to be operative in Fe-Ni and Fe-Ni-C martensites have been determined using a new theory of the crystallography of deformation t~inning.~ This analysis shows that potentially important conventional and nonconventional twinning modes1 have been omitted in previous analyses. Discussion is given on the relevance of the predicted twinning modes to the lattice invariant shear associated with the martensite transformation in steels and to anomalous deformation twinning in Fe-Ni-C martensites. THE two most important criteria which appear to govern operative twinning modes in metallic structures1 are that the magnitude of the twinning shear should be small and that the twinning shear should restore the lattice or a multiple lattice in a twin orientation. The latter criterion ensures that the shuffle mechanism required to restore the structure in a twin orientation is simple. These criteria have been adhered to in the prediction of twinning modes2"6 in bcc and bct single-lattice structures with axial ratios in the range y = 1 to 1.09 as, for example, encountered in martensite occurring in steels. Refs. 2 and 3 in particular consider the martensite transformation in steels and the twinning modes in these cases relate to transformation twinning, and hence the lattice invariant shear associated with the martensite transformation. The list of twinning modes which can be compiled from these sources is incomplete and the ranges of magnitude of shear considered could be unrealistically small, particularly in the case of deformation twinning. The latter consideration is supported by the fact that twinning modes with magnitudes of shear large compared with the smallest shear consistent with a simple shuffle mechanism have been established in, for example, the single-lattice structure mercury7 and the multiple-lattice structure zirconium.&apos; In addition the anomalous deformation twins reported by Ftichrnan4 to occur in a range of Fe-Ni-C martensites still remain unexplained. It is clear that a comprehensive analysis of twinning modes likely to be operative in martensite In steels is required. The results of the application of a new theory of the crystallography of deformation twinningg to these structures are presented in this paper. The theory has been used to determine all shears which restore the lattice or a multiple lattice in a new orientation with magnitude of shear up to a required maximum. The orientation relationships between parent and twinned lattices are not restricted to the classical orientation relationships of reflection in the twin plane or a rotation of 180 deg about the shear direction. PREDICTED TWINNING MODES Twinning modes which restore all or one half of lattice points to their correct twin positions will be referred to as m = 1 and m = 2 modes, respectively. These modes are the most likely to describe operative modes in single lattice structures. The bcc m = 1 and m = 2 modes which have magnitudes of shear s in the range s < 2 and s < 1, respectively, have been given10 and are reproduced here in Tables I and 11. Detailed discussion of the crystallography of these modes and cubic modes in general will be discussed elsewhere (~evis and rocker, to be published). The four twinning elements Kl, &,ql,7)2 as well as the magnitude of shear s are given for each twinning mode, and the twinning modes are given in order of increasing shear. Two twinning modes are given in each row of the tables, the twinning mode Kl, Kz, ql, q2 and the reciprocal twinning mode with elements Kl = K,, Ki = Kl, q: = q2, and 17; = ql. The m = 1 and m = 2 twinning modes which describe twinning shears with small magnitudes of shear and simple shuffle mechanisms in bct crystals with -y = 1 to 1.09 are given in Tables I11 and IV, respectively. On increasing the symmetry of the tetragonal lattice to cubic, that is making y = 1, all modes listed in Tables 111 and IV must reduce to crystallographically equivalent variants of the modes given in Tables I and 11, respectively, or become twinning modes with both shear planes as symmetry planes in the cubic lattice and hence not considered in Tables I and 11. With the exception of this last type of mode only those tetragonal twinning modes which reduce to modes 1.1, 1.2, 2.1, and 2.2 of Tables I and I1 are considered in Tables 111 and IV. For values of y in the range -y = 1 to 1.09 the tetragonal modes and the corresponding cubic twinning modes have approximately the same magnitude of shear. The twinning modes listed in Tables 111 and IV are therefore by the criteria given above the most

Jan 1, 1969

By H. O. Hofman

INSTITUTE OF TECHNOLOGY, In deternlining experimentally the fusibility of clays, two kinds of methods may be distinguished—the direct and the indirect. Of the direct methods, that of Seger has found

Jan 1, 1899

By Herbert Hoover

DURING the year, the&apos; Institute has made the most remarkable growth in its history. Our actual increase in membership was 1816 and therefore was 80 per cent. larger than any previous year. Even without expectation of any abnormal growth, we should pass in the year 1921 the 10;000 mark. The causes of this increased growth are not far to seek.. They lie in the widening vision of the Institute&apos;s work, not only in its relation to&apos; the profession but as an avenue of service to the nation as a whole. The Institute is today in the first rank of influence among public institutions in the country. During this year we have, for the first time in many years, had a ?deficit of some $3000 in our finances. The sum is not important, but it- does indicate the tendency of the times, and that is the high cost of living:&apos; The increase in our expenses lay, to the largest degree, on the publishing side of the Institute&apos;s work. If we compare the year 1918, as a fairly repre¬sentative year, with that of 1920, we find that the costs of issuing the&apos; Institute&apos;s publications, after deducting the income received from these publications, shows a .net increase of about $33,000. for the year. This has been to some degree due to the enlarged membership but to a large degree due to the cost of the paper and printing.

Jan 1, 1921

By W. Mostowitsh

I. Introductory LEAD sulphate occurs as anglesite, and is formed in every roasting of lead sulphides or sulpho-salts containing lead. In smelting in the blast furnace an ore containing natural or artificial lead sulphate, a large part of the sulphur present goes to the formation of the intermediary product matte which requires further treatment for the recovery of the values it contains. It is therefore of importance to study the behavior of lead sulphate at elevated temperatures, both without and with reducing agents, especially as the information available gives data which are more or less conflicting. II. Decomposition of Lead Sulphate by Heat The dissociation of PbSO4 into PbO and S03 or S02 and 0 has been discussed by many metallurgists. The following data are considered to be representative. Doeltz and Graumann1 found that PbSO4 was not affected by heat at 800° C.; that dissociation began at 900° C., and was rapid at 1,000° when the salt lost in 1 ½ hr. 14.3 per cent. of its weight, the dry salt containing 26.43 per cent. SO3. Hofman and Wanjukow2 summarize their work upon the dissociation of metallic sulphates with the statement that the decomposition of PbSO4 begins at 195° C., but progresses very slowly, with the formation of the basic salt 6PbO.5S03 at 705°; that this salt undergoes a transformation at 847°, begins to be decomposed at 888°, to sinter at 896°, and to fuse at 910°; rapid dissociation begins at 952°, and is accompanied by volatilization of PbO; retardations at 958° and 962° indicate an acceleration of decomposition which, however, is not complete. Proske3 found that PbSO4 gave off at 900° C. in 30 min. only 0.63 per cent. of its SO3, and that the loss increased with

Jan 5, 1916

By Howard N. Eavenbon

The low-volatile, or smokeless, coal field of southern West Virginia is in Fayette, Raleigh, Wyoming, Mercer, Summers and McDowell counties, in the extreme southern portion of the state, and extends into the adjacent counties of Tazewell and Buchanan in Virginia. McDowell County is the largest producer, with Fayette and Raleigh counties next. The total area of the field (Fig. 1) is approximately 1600 square miles, or 1,024,000 acres. The percentage of volatile matter in the various seams ranges from 15 to 26 per cent, The upper limit of true low-volatile coal is usually considered to be 23 per cent volatile matter; above this point, the coal usually is classed as medium volatile. This limit will be used in this paper. Geological Position of Seams The smokeless seams are among the oldest coal seams in the country, as the Pocahontas group of rocks is the lowest member of the coal-bearing series and rests on top of the Mauch Chunk red shale, in or below which no coal seams of any importance occur. The Pocahontas group, or Lower Pottsville measures, has a thickness of 750 ft. in southern McDowell County, which decreases to about 350 ft. at Prince, on the New River, in Fayette County, 50 miles to the northeast. In this group, at various points, 12 coal beds have been found, of which 4 have been found in workable thickness and are now being mined. The New River group, or Middle Pottsville measures, is just above the Pocahontas group and varies in thickness from 1300 ft. in southern McDowell County to about 700 ft. along New River. At various places, 16 beds of smokeless coal have been identified in this group, of which 5 have been found in workable thickness and are now being mined. A general columnar section of these strata is shown on Fig. 2. The workable seams in these strata, arranged in geological sequence, are as shown on page 77.

Jan 1, 1932

By T. Wasson

The same limitations&apos; that characterized 1931 existed in the old fields of Indiana and Illinois during 1932. Prices remained low. The average for the year for Illinois and southwestern Indiana was $1.032 as against $0.852 for 1931 and $1.616 for 1930. In September a curtailment of production of about 25 per cent became effective and was continued to the end of the year. There were no new discoveries and very little wildcatting was done. Considering the age of the wells, and the number still producing, there were few abandonments. The most outstanding thing about the old fields in these states is their long continued productivity. Illinois The fields along the southeast end of the LaSalle anticline had their peak of 33,686,000 bbl. in 1908. In 1932, with a 25 per cent restriction for 355 months, these fields produced 4,661,000 bb1.l There were 52 new completions (most of them in old territory) and of these 33 were dry, 8 were gas, and 11 were oil wells. The new oil wells had a total initial of 102 bbl., or an average of 9.3 bbl. per well. Nineteen of the new producers were in Crawford County. There were about 200 wells abandoned in the old southeast fields in 1932 as compared to 210 in 1931. The greatest number, 86, were in Lawrence County. To the end of 1932, the four major counties—Clark, Crawford, Lawrence and Wabash—had produced almost 394,000,000 bbl. from 92,160 acres. Better than one-half of this was produced in Lawrence County from 26,240 acres. The Dupo area of Sinclair County had no additions to production although four wells were drilled. On the Jacksonville structure in Morgan County, six gas wells with an average depth of 300 ft. were drilled to sands in the base of the Pennsylvanian. They produced an open-flow total initial of 2,000,000 cu. ft. This gas will be developed further to supply a local market.

Jan 1, 1933

By M. A. Hunter

IN the present state of public affairs, the reviewer turns from his traditional role of recording the progress made in research during the year and views the whole situation in which he finds himself in direct relation to the immediate needs of the nation. The slow progress of research year by year fades into comparative insignificance. The sum total of that research in all the years which have past becomes of importance only in direct relation to the extent to which we have translated or can immediately translate it into in¬dustrial production. For in a wartime economy immediacy is of paramount importance. The outcome of the war is being determined by our ability to pro¬duce and fabricate the metals and alloys which we require for its prosecution. Aside from iron and steel which lie outside the limits of this review, the most important of the nonferrous metals now needed in wartime production are aluminum, magnesium, nickel, chromium, and manganese. Some remarks on their production and fabrication follow.

Jan 1, 1942

By Y. C. Liu, R. H. Richman

The effects of gel,manium and tin on the deformation and 9-e-crystallization textures of copper have been explored in detail with in the copper-rich terminal solid solutions. Addition of solute to copper produces a change in deformation texture from the copper type to the 70 :30 brass type. This transition has been measured quantitatively The types mid proportions of recrystal-lization components have been determined as a function of com-position, and correlation of recrystallization components with specific deformation components is discussed. On the basis of information available in the literature, it has been suggested that the effect of solute elements on the recrystallization texture of copper

Jan 1, 1961

By E. S. Moore

ALTHOUGH nickel was in use in alloys long before the Christian era, the metal was not discovered until 1751, when Cronstedt recognized it in niccolite from Sweden. The Chinese apparently used a nickel alloy, known as "pahfong" thousands of years ago and Persian coins dating farther back than 200 B.C. consist of a copper-nickel alloy similar to some of those now in use in coins. The pure metal was first prepared about 1775 and the metal was refined for commercial purposes some years later. The nickel industry did not attain much prominence until the ores in New Caledonia were discovered. Exports of ore from that country began in 1875 and since that date there has been an ever-increasing world output of nickel and a great expansion in the uses of the metal except during short periods of commercial and industrial depression. Previous to 1875, for a number of years, Norway was the chief producer, although the metal was mined also in Sweden, Finland, Italy, Germany, Austria, France, China, the United States and other countries. With the dis-covery of nickel deposits in the Sudbury district, Ontario, a new factor was introduced into the nickel industry and Sudbury has since become the overwhelmingly dominant feature in the world&apos;s nickel markets. Although nickel was first discovered in Canada as early as 1848 near the north shore of Lake Huron and nickel-copper sulfides were found in 1856 by surveyors working close to the present location of the important mine at Creighton, in the Sudbury field, it was not until 188.3 that any importance was attached to this field. In that year copper sulfide attracted attention where the main line of the Canadian Pacific railroad was being projected across Canada to the Pacific coast. Mining began near this discovery in 1889 but in the meantime operations had begun in 1886 in other parts of the field and by 1890 about 100,000 tons of ore had been raised. In the Sudbury field, as in Norway and at the old Lancaster Gap mine in Pennsylvania, the ore was first mined for its copper content and difficulty in the refining of the copper led to the discovery of the important proportions of nickel in the ore. No. 3 property of the Inter-national Nickel Co., now known as the Frood, the greatest deposit in the

Jan 1, 1932

By Ernst A. Hauser

IN a paper published three years ago,&apos; the term "silicic chemistry" was used for the first time to emphasize the increasing importance of the chemistry of silicon in science and technology. The development through which the colloid chemistry of siliceous matter has gone since then is in itself ample proof that the coining of this new term for this branch of colloid science was not presumptuous. Until quite recently, however, silicic chemistry concerned itself only with the composition and colloidal properties of natural and synthetic siliceous matter, but had not paid much attention to the genesis of this matter, particularly to that of the clay minerals. What is even more disturbing, particularly from an educational point of view, is the fact that neither mineralogy, geology, nor metallurgy has fully realized the important role colloidal phenomena must have played in the genesis of our planet and the formation of minerals generally speaking. Considering the importance of colloid chemistry today in the fields just mentioned, it is not surprising that the theories most agreed upon by geologists and mineralogists for the origin of clay minerals are not acceptable from a strictly colloid chemical point of view for the genesis of these most important and most abundant components of the earth. Of all the theories pertaining to the origin of clay minerals, those still most accepted by geologists and mineralogists are the "residual clay" and the "transported clay" theories.15 The former is based primarily on the assumption that the formation of clay minerals is the result of surface weathering of fresh rocks, or is due to the action of solutions. Taking the action of water on orthoclase as an example, the most recent ideas have been summarized by H. Jenny13 as follows:

Jan 1, 1952

By J. T. Lapsley, I. I. Cornet, A. E. Flanigan, R. Hultgren, J. E. Dorn

With the greatly expanding use of magnesium during the war, it appeared necessary to the War Metallurgy Committee that procedures of heat treating common magnesium casting alloys be investigated systematically. Accordingly, the National Defense Research Committee of the Office of Scientific Research and Development placed a research contract with the University of California, supervised by the War Metallurgy Committee. Research on the solution heat treatment and aging of magnesium alloy AZg2, (formerly ASTM No. 17; also known as Dowmetal C or AM26o) which was done under "Restricted" Project NRC-2I, in 1942-1943, and reported in detail in a final report to the OSRD on September 3, 1943, is the basis of this paper, which has been released for publication by the OSRD. American experience with magnesium alloys prior to World War II was limited, although some of these alloys had been in commercial use since 1909. Requirements of the aircraft industry for light alloys made it imperative to understand and utilize the advantageous strength-weight properties of magnesium castings. Magnesium casting alloys are commonly solution heat- treated to increase their ultimate tensile strength and ductility; this treatment may be followed by an age hardening at elevated temperatures, which raises the tensile yield strength but diminishes the ductility. In the present investigation, AZp was studied to determine the effects on properties of various solution heat treatment and aging schedules. The principles of heat treatment of magnesium alloys are the same as for other non-ferrous alloys. The alloy studied, AZp, has a nominal composition of 9 pct aluminum, 2 pct zinc, and minor constituents. Fig I shows, by the projection of isothermal sections on the concentration plane, the solubility surface1 of the ternary magnesium-rich solid solutions as determined by X ray &apos;analysis. From this figure it may be seen that above approximately 375°C (707OF), AZp alloy is a single phase alloy at equilibrium; below this temperature the equilibrium condition is a two phase alloy. The beta constituent which precipitates from the solid solution exerts a hardening effect. Because the zinc concentration is only 2 pct, ancl because of its solubility relations, AZqz resembles a binary alloy of magnesium with aluminum. The solubility curve1 of Fig 2 shows how rapidly the solubility of the beta phase decreases with decreasing temperatures. Unlike many aluminum alloys, magnesium alloys do not age harden at room temperatures; precipitation hardening of AZ² alloy is performed at about 177°C (350°F). At this temperature about 3 pct aluminum

Jan 1, 1949

By A. E. Zawadzki

A progress report is presented on the development of a process for the removal of sulfur dioxide from flue gases. Catalytic oxidation of the sulfur dioxide in flue gases, with the production of recoverable sulfuric acid, has been demonstrated to be technically feasible. Problems associated with the process are discussed. The need for an inexpensive and efficient process for controlling sulfur dioxide emissions from utility plant stacks has been accentuated by the ever-increasing public demand for elimination of all man-made air pollutants. I would like to describe the results of an investigation of the development of such a process; more important, I would like to present a discussion of the problems associated with the process which remain to be solved. The research work on the BCR catalytic gas phase oxidation process has been jointly sponsored by the Association of Edison Illuminating Cos., Edison Electric Inst. and Bituminous Coal Research, Inc., since 1958. However, work on SO2-pollution abatement was initiated by BCR in 1953. Tieman and Clymer,1 working with ozone and simulated flue gases, evaluated a gas phase oxidation process for removing SO2 from flue gases. Their experimental data indicated that the use of ozone to oxidize SO2 in flue gas concentrations, with subsequent recovery of H2SO4, did not appear to be economical due to the large ratio of ozone to sulfuric acid produced (2.6 to 1). The cost of the ozone would be 6 to 10 times the cost of sulfuric acid produced. As a result of the ozone study, work on a catalytic oxidation process was developed. The following reactions are the basis for the catalytic oxidation process Reaction [I] normally occurs in the combustion of sulfur-bearing fuels. At the high temperature found in the combustion chamber, 95% to 99% of the sulfur in the fuel is oxidized to SO2 and 1% to 5% is oxidized to SO3. The concentration of SO2 in the combustion gases depends on the combustion efficiency and the quantity of excess air used. A commonly used rule of thumb is 0.1 percent by volume SO2 in the flue gas for each 1% sulfur in the fuel. Reaction [2] proceeds at a wide range of temperatures. The rate of the reaction is rapid above l,000°F; however, the equilibrium conversion drops rapidly above this temperature. 2 Reaction [3] occurs rapidly to completion at temperatures below 400°F; above this temperature some SO3 exists in equilibrium with H2SO4. Complete dissociation of H2SO4 occurs above 650°F.3 The simplicity of the proposed process provided added incentive to the development and evaluation of the various component unit operations. The advantages of the process were considered to be as follows: 1) no raw materials were required, 2) the unit operations were not radically new; and 3) a salable product, sulfuric acid, would be produced. The successful development of the process was contingent upon the solution of several major problems: 1) The development of a catalyst which would provide high catalytic activity at reasonable conditions of gas flow and temperature without causing an unacceptable increase in pressure drop. 2) The development of a high temperature dust collection system to provide clean flue gases to the catalytic reactor. 3) The complete recovery of the sulfuric acid produced in the process; the effluent gas must contain less than 20 ppm by volume of sulfuric acid. As of this date, the complete solution to these problems has not been achieved. EXPERIMENTAL Catalyst Development: The use of platinum and vanadium catalysts for the production of sulfuric acid by the treatment of dry gases containing 5% to 20% by volume sulfur dioxide has been known for many years. The application of the basic idea of catalytic oxidation of sulfur dioxide in flue gas concentrations was

Jan 1, 1965

By N. N. Breyer

A specially built "hard" tensile machine with characteristics permitting the precise detertnination of the drop of the load at the yield point has been used to study the magnitude of the yield-point phenotnenon in prestrained martensitic 4340 steel. A new phenonzenon, the appearance of a secondary yield point, has been observed by holding the specimen at constant strain in the plastic region. Furthermore, it has been found that a series of yield-point drops could be introduced by successive constant strain holds in the plastic region. The isothermal kinetics of the development of the secondary yielding point lave been studied at four temperatures: 24° 0° -18°, and -79°C. From the results of the kinetic investigation, equations for the In a previous investigation1 it was shown that, contrary to generally held opinion, steels of medium carbon content, such as 4340, 4140, and 86B30, in the as-quenched martensitic condition, can be cold-drawn through a die with reductions in area of up to 10 pct without cracking. Tensile specimens of 4340 machined from bars quenched and prestrained in this manner exhibited tensile strengths of about 400,000 psi coupled with 30 pct reductions in area. In addition, it was found that each sample of such steels exhibited a yield point in the quenched, cold-drawn condition. Since these studies were conducted on a commercial hydraulic testing machine of a type which is not well-suited to detailed study of yield-point behavior, it was decided to study this phenomenon more thoroughly on a rigid straining machine. In this new investigation, use of such a "hard" machine not only allowed study of the magnitude of the yield-point drop but also revealed a new phenomenon—secondary yielding of the martensite introduced by stopping crosshead motion after plastic deformation of the sample had begun. The present paper is a report of these findings. MATERIALS AND PROCESSING The material used was a commercial 4340 steel of the composition shown below: 0.41 0.80 0.013 0.019 0.31 0.85 1.76 0.28 1 0.42 0.77 0.015 0.024 0.30 0.84 1.69 0.28 0.08 2 1 = Ladle analysis. 2 = Laboratory analysis. Bars of this steel were processed in the following way: 1) machined to predetermined diameters; 2) austenitized at 870°C for 1 1/2 hr; 3) oil-quenched; 4) cooled to -115°C for 1/2 hr; onset and increase in magnitude of the secondary yielding in this temperature region have been found to fit the relationship ?Ys = Atn where ?Ys is the magnitude of the secondary yield Point in psi, t is the time in seconds, and A and n are parameter characteris-tics of the material. Although the occurrence of the primary and secondary yield points could be rationalized qualitatively on the basis of stress-induced ordering of carbon atoms in the stress fields of dislocations, as postulated in an earlier paper, the kinetics of the secondary-yield-point development were interpreted to indicate that the ordering involves more than just single jumps of carbon atoms from high-energy to neighboring low-energy sites. 5) pickled and lime-coated; 6) drawn through a carbide die. The predetermined diameters were chosen so that drawing through the same die gave the various reductions desired. Tensile specimens of 0.252 in. diam with a 1 1/4 in. gage length were then prepared from the drawn bars and tested. In order to study the stress-strain behavior at the yield point in detail, a rigid tensile machine with a high spring constant was constructed. Columns of large cross section (relative to the specimen cross section) constituted the machine frame. A dc motor was used to drive a screw via a gear reducing train and a "crane" thrust bearing. In this relatively simple device small deformations could be observed un-blurred by the slow response and lower spring constant inherent in hydraulic machines.&apos; A strain-gage dynamometer permitted load changes as small as 8 lb to be read. RESULTS Tensile test samples machined from bars in the as-quenched condition with no subsequent drawing and samples from bars with 3.8 pct reduction after quenching gave stress-strain curves typified by those shown in Figs. I and 2. The time lapse between predrawing and tensile testing varied but usually ranged between 3 to 6 days at room temperature. The strain rate during testing was 0.003 in. per in. per min. The as-quenched curve is seen to have a broad serrated maximum whereas the stress on the specimen prestrained 3.8 pct rose linearly to point A, Fig. 2, fell abruptly to B, and then gradually to C. The abrupt drop to B was accompanied by evidence of incipient necking. The drop of the stress at the yield point in the prestrained samples (A to B in Fig. 2) changed with the percent prestrain, as illustrated on Fig. 3. Although the tensile strength increased continuously with the amount of previous cold drawing, the magnitude of the yield point drop first increased—up to about 6 pct prior reduction—and then decreased. Specimens from bars predrawn more than 8 pct broke in a brittle fashion in the elastic portion of the stress-strain curve.

Jan 1, 1967

By E. S. Moore

Although nickel was in use in alloys long before the Christian era, the metal was not discovered until 1751, when Cronstedt recognized it in niccolite from Sweden. The Chinese apparently used a nickel alloy, known as "pahfong" thousands of years ago and Persian coins dating farther back than 200 B.C. consist of a copper-nickel alloy similar to some of those now in use in coins. The pure metal was first prepared about 1775 and the metal was refined for commercial purposes some years later. The nickel industry did not attain much prominence until the ores in New Caledonia were discovered. Exports of ore from that country began in 1875 and since that date there has been an ever-increasing world output of nickel and a great expansion in the uses of the metal except during short periods of commercial and industrial depression. Previous to 1875, for a number of years, Norway was the chief producer, although the metal was mined also in Sweden, Finland, Italy, Germany, Austria, France, China, the United States and other countries. With the discovery of nickel deposits in the Sudbury district, Ontario, a new factor was introduced into the nickel industry and Sudbury has since become the overwhelmingly dominant feature in the world&apos;s nickel markets. Although nickel was first discovered in Canada as early as 1848 near the north shore of Lake Huron and nickel-copper sulfides were found in 1856 by surveyors working close to the present location of the important rnine at Creighton, in the Sudbury field, it was not until 1883 that any importance was attached to this field. In that year copper sulfide attracted attention where the main line of the Canadian Pacific railroad was being projected across Canada to the Pacific coast. Mining began near this discovery in 1889 but in the meantime operations had begun in 1886 in other parts of the field and by 1890 about 100,000 tons of ore had been raised. In the Sudbury field, as in Norway and at the old Lancaster Gap mine in Pennsylvania, the ore was first mined for its copper content and difficully in the refining of the copper led to the discovery of the important proportions of nickel in the ore. No. 3 property of the International Nickel Co., now known as the Frood, the greatest deposit in the

Jan 1, 1932

By A. Tonejc, A. Bonefacic

As can be seen from the phase diagram A1-W1 the equilibrium solubility of tungsten in aluminum is practically nil at room temperature. By quenching from the liquid state (50,000°C per sec), Varic, Burov, and Kolesnicenko2 obtained A1-W solid solutions up to 0.15 at. pct W. The quenched alloys were in the form of foils, 0.2 to 0.3 mm thick. Considering the results of Duwez and Willens,3 it is obvious that this thickness, which makes impossible a sufficiently rapid quenching, was the main reason for the relatively low content of tungsten dissolved in aluminum found by varic.2 he present note shows that the metastable solubility of tungsten in aluminum can be appreciably extended in aluminum-rich A1-W alloys. The quenching technique and the procedure employed for the preparation of the alloys have been described previously.475 The resulting quenched flakes varied in thickness from 1 to 20 µm from experiment to experiment. However, the measurements of the lattice parameters were carried out only with flakes thinner than 5 µm. The areas of quenched flakes were between 0.1 and 15 mm2. The quenched flakes were placed into a 0.3-mm glass capillary tube which was then mounted in a 114.6-mm-diam Debye-Scherrer camera. Straumanis asymmetric film position and nickel-filtered CuKa radiation were used. The lattice spacings were computed taking X(CuKa1) = 1.54050A for resolved and ?(CuKa) = 1.54178A for unresolved doublets. All specimens were rotated at room temperature, 26o +2°C. The lattice parameters were estimated from extrapolation against the Nelson-Riley function. It was estimated that the error in the lattice parameter of the measurements on a single film lies within +0.0004A for lower and about +0.001A for higher concentrations of tungsten. The lattice parameters of the metastable solid solutions A1-W are plotted vs the concentration of tungsten in Fig. 1 together with the parameters measured by previous investigators.&apos; Each point of the present measurements represents a determination of the lattice spacing on different quenched flakes, for a given concentration of tungsten. With experimental accuracy, the lattice parameters of the metastable solid solutions fall on the straight line passing through the already known data.&apos; As estimated from the uncertainties in the lattice spacings of the solid solutions, the alloys were homogeneous within 0.1 at. pct W. The solubility of tungsten in aluminum-rich A1-W solid solutions obtained by a very rapid quenching technique is increased to about 0.95 at. pct W. This value is 6 times greater than the amount known up to now. -he lattice parameters of the resultant aluminum solid solutions with higher concentrations of tungsten than 0.95 at. pct W did not remain constant AUGER electron spectroscopy has been used to clarify the role of impurities in the embrittlement of AISI 3340 steel. Analysis of fracture surfaces has shown that the embrittled condition is correlated with appreciable antimony segregation at grain boundaries. The low temperature (400" to 600°C) temper embrittlement of low alloy steels containing various combinations of Cr , Ni , Sb , Mn , P , Sn , and As has been examined extensively for many years. General reviews of the area have been made by McMahon1 in 1968, LOW&apos; in 1959, woodfine3 in 1953, and Holloman4 in 1946. Recent work by Low, Stein, Turkalo, and LaForce5 has done much in separating the alloy and

Jan 1, 1970

By H. L. Marcus, P. W. Palmberg

As can be seen from the phase diagram A1-W1 the equilibrium solubility of tungsten in aluminum is practically nil at room temperature. By quenching from the liquid state (50,000°C per sec), Varic, Burov, and Kolesnicenko2 obtained A1-W solid solutions up to 0.15 at. pct W. The quenched alloys were in the form of foils, 0.2 to 0.3 mm thick. Considering the results of Duwez and Willens,3 it is obvious that this thickness, which makes impossible a sufficiently rapid quenching, was the main reason for the relatively low content of tungsten dissolved in aluminum found by Varic.2 he present note shows that the metastable solubility of tungsten in aluminum can be appreciably extended in aluminum-rich A1-W alloys. The quenching technique and the procedure employed for the preparation of the alloys have been described previously.475 The resulting quenched flakes varied in thickness from 1 to 20 µm from experiment to experiment. However, the measurements of the lattice parameters were carried out only with flakes thinner than 5 µm. The areas of quenched flakes were between 0.1 and 15 mm2. The quenched flakes were placed into a 0.3-mm glass capillary tube which was then mounted in a 114.6-mm-diam Debye-Scherrer camera. Straumanis asymmetric film position and nickel-filtered CuKa radiation were used. The lattice spacings were computed taking X(CuKa1) = 1.54050A for resolved and ?(CuKa) = 1.54178A for unresolved doublets. All specimens were rotated at room temperature, 26" +2°C. The lattice parameters were estimated from extrapolation against the Nelson-Riley function. It was estimated that the error in the lattice parameter of the measurements on a single film lies within +0.0004A for lower and about +0.001A for higher concentrations of tungsten. The lattice parameters of the metastable solid solutions A1-W are plotted vs the concentration of tungsten in Fig. 1 together with the parameters measured by previous investigators.&apos; Each point of the present measurements represents a determination of the lattice spacing on different quenched flakes, for a given concentration of tungsten. With experimental accuracy, the lattice parameters of the metastable solid solutions fall on the straight line passing through the already known data.&apos; As estimated from the uncertainties in the lattice spacings of the solid solutions, the alloys were homogeneous within 0.1 at. pct W. The solubility of tungsten in aluminum-rich A1-W solid solutions obtained by a very rapid quenching technique is increased to about 0.95 at. pct W. This value is 6 times greater than the amount known up to now. -he lattice parameters of the resultant aluminum solid solutions with higher concentrations of tungsten than 0.95 at. pct W did not remain constant AUGER electron spectroscopy has been used to clarify the role of impurities in the embrittlement of AISI 3340 steel. Analysis of fracture surfaces has shown that the embrittled condition is correlated with appreciable antimony segregation at grain boundaries. The low temperature (400" to 600°C) temper embrittlement of low alloy steels containing various combinations of Cr, Ni, Sb, Mn, P, Sn, and As has been examined extensively for many years. General reviews of the area have been made by McMahon1 in 1968, LOW&apos; in 1959, woodfine3 in 1953, and Holloman4 in 1946. Recent work by Low, Stein, Turkalo, and LaForce5 has done much in separating the alloy and

Jan 1, 1970

By J. D. Hanawalt, W. H. Gross

Magnesium has long been known as the lightest of our engineering metals. This metal, silvery white in color, has a specific gravity of only 1.74. Aluminum, the next lightest structural metal, is 1 ½ times heavier; zinc is 4 times heavier; iron and steel are 4 ½ times heavier; and copper and nickel are 5 times heavier. Magnesium does not occur in the free state but is very abundant in nature, constituting 2.5 pct of the earth&apos;s crust in the form of various ores. It is the third most abundant structural metal, being exceeded only by iron and aluminum. Magnesium is unique, however, in that in the form of magnesium chloride it also exists in the oceans. Sea water is the source most widely used for production in the United States but magnesium is also commercially produced from magnesite, dolomite, and other ores as well as from certain inland brines. The vast quantity of magnesium existing in the waters of the oceans can be visualized when it is realized that the removal of one hundred million tons per year (the approximate annual steel production in the United States) for a million years would reduce the magnesium content of sea water only from 0.13 to 0.12 pct, providing no more magnesium had washed into the sea in the meantime. Not only is magnesium potentially very abundant but it is in addition a very versatile metal and can be shaped and worked by practically all methods known to the art of metal working. It can be cast by sand, die, and the various permanent-mold methods;

Jan 1, 1953

By Sydney H. Ball

AMERICAN consumption of industrial diamonds has increased five fold in the past 25 years and today accounts for 15 to 20 percent of the world&apos;s sale of rough diamonds. In another decade the value of industrial diamonds sold may well equal or exceed that of gemstones. It is generally understood that industrial diamonds are one of the strategic minerals being stocked by the Government in the present crisis to ensure rapid and efficient armament production. Diamond die making is a trade largely confined to artisans in Switzerland and in certain parts of France. Today, in addition to turning out pilots, we should train expert artisans in diamond die making, for thousands of miles of tremendously small-gauge wire will be needed to make the instruments by which the efficiency and safety of these pilots is assisted.

Jan 1, 1941

By E. G. Dahlgren, Dan O. Howard

THE West Edmond oil field, which covers parts of Oklahoma, Canadian, Kingfisher, and Logan Counties in the State of Oklahoma, is in geographical extent the largest single oil field found in the state. At the present time, its area of 26,800 acres is almost twice as large as the Oklahoma City field, which hitherto was the state&apos;s largest field. Many authorities believe that the West Edmond field is the most important oil pool found in the United States since Pearl Harbor. The discovery of the field without the help of geological, geophysical, or other recognized technical information, the fact that the oil and gas accumulated in a stratigraphic or wedge-type trap, and the rapid development of the productive area under wartime conditions are some of the interesting features of the field. The West Edmond field lies west of the Oklahoma City, Britton, and Edmond fields. The field is in an area that has been considered on the west flank of the Granite Ridge line of folding, on which a number of Central Oklahoma&apos;s most important oil fields are located. Over a period of years, especially since the discovery of the new pools such as Oklahoma City, Edmond, Britton, and Crescent, the general area of the West Edmond field has been explored intensively by geological and geophysical methods. This led at times to the drilling of a few dry Wilcox sand tests.

Jan 1, 1945