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By Herbert H. Uhlig

Although the mechanical properties of high-carbon manganese-iron alloys, particularly the Hadfield manganese steels, have been established, the literature discloses discrepancies in the reported properties for the low-carbon alloys. Hadfieldla summarized the existing data up to 1927, including the investigations of Guillet, Arnold, Strauss, Burgess and Aston, and reported his own values for alloys containing for the most part from 0.06 to 0.I5 per cent carbon. He noted: From these comparisons it wil! be seen that while there is a broad and general agreement as to the character of the alloys at the different manganese percentages, there are disparities in individual cases, especially as regards the degree of toughness or brittleness displayed by an alloy with certain percentages and with particular types of treatment. These differences are not always readily explainable.lb His data showed that alloys containing 4 to 10 per cent manganese water-quenched from Iooo°C. were brittle and hard with maximum brittleness at about 7 per cent. Slight improvement in ductility was obtained with compositions from 10 to 17 per cent manganese. Alloys containing up to 17 per cent manganese slowly cooled rather than quenched from 87o°C., he found, were slightly improved in ductility with significant improvement in alloys analyzing 4.1 and 4.8 per cent manganese. Recently Walters, Kramer and Loring2 reported mechanical properties for alloys made up from electrolytic manganese and ingot iron and containing from 0.02 to 0.04 per cent carbon. They showed that a tempering treatment at 54o°C. (Iooo°F.) for one hour significantly improved the ductility of compositions ranging from 6.7 to &apos; 20.7 per cent manganese. The differences of these compared with Hadfield&apos;s results they considered to originate in this tempering treatment plus the fact that Hadfield&apos;s alloys contained higher carbon and phosphorus (0.06 to 0.I5 per cent C; 0.06 to 0.07 per cent P compared with 0.02 to 0.04 per cent C, <o.ooI per cent P). In this paper it is shown that of the low-carbon alloys (0.02 to 0.03 per cent) containing from 3.3 to 21.5 per cent manganese moderately or rapidly quenched from IOOO°C. some are brittle or ductile, depending on presence or absence of hydrogen. Hydrogen is readily absorbed at high temperatures, and much of it is retained when the alloys are cooled to room temperature. The presence of hydrogen in the range of composition from 10 to 18 per cent manganese is a major factor in determining relative ductility. At 22 per cent manganese, and also at compositions below 10 per cent manganese, factors other than or in addition to hydrogen play a role. These are discussed. Also data are presented to show that hydrogen absorbed by the high-carbon alloys of Hadfield composition is without effect on their mechanical properties.

Jan 1, 1944

By Ramesh Malhotra, Hubert E. (Deceased) Risser

THE WORLD Coal, as a source of energy and as a source of coke for the smelting of iron ore, has contributed significantly to the development of every major industrial nation of the world A number of other materials-oil, natural gas, wood, waste materials, water, and, in some applications, nuclear materials -can be used satisfactorily for the generation of heat and energy, but no generally acceptable and economic substitute has been found to supplant coke in iron ore smelting in conventional blast furnaces. In the development of many nations, coal provided the initial source of energy for industrialization Although coal provided more than 60% of the world&apos;s energy each year between 1902 and 1929, oil and natural gas have surpassed it as a source of energy in more recent years (Ref. 38, pp. 439, 441). Despite the rapid rise in importance of other fuels, a considerable amount of the total energy consumed is still supplied by coal. In 1972, coal supplied 32.1 % of the total world energy (Ref. 49, pp. 2-3). To produce this energy, 2.4 billion metric tons of coal were consumed-a 16.0% increase over the amount consumed in 1962. A further worldwide increase in the amount of coal used to supply energy is projected. According to Dr. Karlheinz Bund (Ref. 37, p 145), by the year 2000 world coal consumption could amount to 5 billion mt. Coal Resources and Production The world&apos;s coal resources are estimated to be about 10,872 billion mt. Of this amount, 1,297 billion mt are classified as measured reserves (Ref. 50, p. 57). In Table 13.A.1 the estimates of measured reserves and total resources, recent production, and the ratio of measured reserves to production of major coal-producing countries are shown. About 90% of the world&apos;s total coal resources are estimated to be in the USSR, the United States, and China. The United States ranks second in the world in coal resources, but in measured reserves, it ranks first. Because of the difference in rate at which available coal resources are being exploited, the ratio of measured reserves to actual production varies widely among areas and countries. France and East Germany have the lowest reserve to production ratios, 49.5 and 60.1, respectively. In Mexico, where currently less than 5 million mtpy of coal are produced, the ratio is 1257 For all countries producing more than 200 million mtpy of coal (except East Germany), the ratio ranges from 350 to 670. For the United States, the ratio is 669.7. In Table 13.A.2, distribution of the world&apos;s coal resources by area is shown. More than 97% of the total resources lie in the northern hemisphere, with Asia, including European USSR, having 63.4%. Only 1.9% of the total coal resources are estimat-

Jan 1, 1976

By Thomas A. Read

THE internal friction of single crystals of metals is affected markedly by a variety of factors, which, according to the literature, are without influence on the internal friction of polycrystalline metals at strain amplitudes less than 10-5. For example, the internal friction of a suitably oriented zinc single crystal is multiplied by a factor of l00 when the vibration amplitude is slightly increased, and the internal friction of a copper crystal is markedly increased by the application of a stress of 30 lb. per sq. in. for one minute. In this paper it will be shown that these, together with the other phenomena associated with the damping of mechanical vibrations in metal single crystals, can be satisfactorily explained, at least qualitatively, in terms of an atomic mechanism that has been proposed for quite another purpose-that of accounting for slip in metals. The extraordinary agreement between the observed behavior of the metal single crystals and the behavior that could be predicted on the basis of this atomic mechanism leads to the belief that the latter is probably essentially correct. If this is so, it follows that valuable information about the slip process in metals may be gained from measurements of internal friction on single crystals. In this paper the results of the only study to date on the damping of mechanical vibrations in single crystals of metals will be presented. EXPERIMENTAL PROCEDURE The internal friction of a material is a measure of the rate at which the energy of mechanical vibrations is converted into heat. The measure of internal friction used in the present paper is the decrement A, which is defined as the fraction of the energy of vibration lost per half cycle. The measurements described here were .made for longitudinal oscillations at a frequency of 33.5 kc. for the copper crystals, and at a frequency of 39 kc. for the zinc crystals. The method used is that of the composite piezoelectric oscillator. The single-crystal specimens are in the form of circular cylinders ¼ in. in diameter and 1 ½ to 2 ½ in. long. The crystal rods are waxed in a V-block and sawed to the proper length with a fine jeweler&apos;s saw. The ends of the specimen are ground flat, and one end is cemented with a very thin film of beeswax and rosin to the end of an x-cut quartz rod which is ¼ in. in diameter and 3 in. long. The length of the specimen rod is determined by the condition that its natural frequency for longitudinal vibration be the same as that of the quartz rod, within 0.5 per cent. The lengths of the specimens are thus different for different orientations of the cylinder axis with respect to the crystallographic axes. When the specimen and quartz rods are thus matched in frequency the adhesive is at a node of stress, and it has been shown experimentally that under these circumstances

Jan 1, 1941

By H. A. Doerner, F. D. DeVaney, J.B. Clemmer

Production of magnesium metal in the United States during the past decade has increased from less than 600,000 lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgCO3), usually is associated with limestone (CaC03) and dolomite (MgCO3. CaC03). It occurs in crystalline and microcrystalline (sometimes termed amorphous) forms.2 The more common crystalline mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedra1 crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories. The deposits are extensive, some veins being hundreds of feet wide. The boundaries of the veins are indefinite, and the magnesite is interfingered with dolomite. Calcite, talc, serpentine, quartz and shale are disseminated through the deposits. The quality of the ore cannot be determined by appearance or by simple tests; chemical analysis is required. These features make it difficult to determine the boundaries or total quantity of workable ore.3 Only the higher-grade ores are mined, and a considerable proportion of the magnesite content is discarded by hand-sorting and log-washing methods. After calcining, the sorted product meets the specifications for usual refractory material, as it contains approximately 81 per cent MgO, 7 per cent SiO2, 6 per cent CaO and 6 per cent Fe203 + A1203. A sample of the reject material had the following analysis after calcining: 65.4 per cent MgO, 6.3 CaO, 21.1 SiO2 and 6.5 R2O3. The percentage reported as R2O3 includes compounds whose chlorides are acid-soluble but give precipitates in ammoniacal solution that are ignited and weighed. The more common constituents are Fe2O3, A1203 and TiO2. The sorted magnesite product is not the best grade. even for refractory purposes, and leaves much to be desired for a reduction process. The rejected material contains a large proportion of magnesite. It is apparent that an effective concentration method would yield a higher recovery and a better product. In general, the refractory grade is not suitably pure for other uses. Recent developments in the production of

Jan 1, 1943

By J. B. Clemmer, F. D. DeVaney, H. A. Doerner

Production of magnesium metal in the United States during the past decade has increased from less than 600,000 lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgCO3), usually is associated with limestone (CaC03) and dolomite (MgCO3. CaC03). It occurs in crystalline and microcrystalline (sometimes termed amorphous) forms.2 The more common crystalline mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedra1 crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories. The deposits are extensive, some veins being hundreds of feet wide. The boundaries of the veins are indefinite, and the magnesite is interfingered with dolomite. Calcite, talc, serpentine, quartz and shale are disseminated through the deposits. The quality of the ore cannot be determined by appearance or by simple tests; chemical analysis is required. These features make it difficult to determine the boundaries or total quantity of workable ore.3 Only the higher-grade ores are mined, and a considerable proportion of the magnesite content is discarded by hand-sorting and log-washing methods. After calcining, the sorted product meets the specifications for usual refractory material, as it contains approximately 81 per cent MgO, 7 per cent SiO2, 6 per cent CaO and 6 per cent Fe203 + A1203. A sample of the reject material had the following analysis after calcining: 65.4 per cent MgO, 6.3 CaO, 21.1 SiO2 and 6.5 R2O3. The percentage reported as R2O3 includes compounds whose chlorides are acid-soluble but give precipitates in ammoniacal solution that are ignited and weighed. The more common constituents are Fe2O3, A1203 and TiO2. The sorted magnesite product is not the best grade. even for refractory purposes, and leaves much to be desired for a reduction process. The rejected material contains a large proportion of magnesite. It is apparent that an effective concentration method would yield a higher recovery and a better product. In general, the refractory grade is not suitably pure for other uses. Recent developments in the production of

Jan 1, 1943

By W. C. Muehlhof, L. D. Lamont

THROUGHOUT the anthracite industry&apos;s history, the problem of handling and dis¬posing of refuse material has been one of major importance. In the early days of the industry&apos;s activities, only the large sizes of anthracite were satisfactory for market requirements and the smaller sizes were deposited as refuse. As time went by, more efficient coal-burning equipment was developed and a market demand was created for the finer sizes of coal. This demand made it possible to recover market¬able coal from banks deposited as refuse in the earlier days of mining. The same condition holds good today and we can see a definite trend toward the objective of utilizing the No. 4 and No. 5 buckwheat sizes. Under present conditions, we know that a limited market exists for No. 4 and 5 buckwheat; we know that the finer sizes of anthracite can be burned as pulverized fuel; we know that these fine sizes can be processed and sold as bri¬quettes, and we also know that the heat content of these fine sizes of coal is compar¬able with that of the sizes now merchan¬dized. Therefore, it should be the objective of the industry to conserve these fine sizes of coal in such manner that if and when processing facilities are developed, and market demands exist, the material can be salvaged and made available to meet these demands. From the standpoint of economical future reclamation, the ideal method of disposing of refuse containing the finer sizes of coal is to deposit it in banks separate and apart from other breaker refuse. By this procedure, the minimum amount of material will be processed in future salvage operations to recover the No. 4 and No. 5 buckwheat sizes. Many collieries in the anthracite region are operated under leases that have a specific term. These lease agreements provide that, upon expiration of the lease by term, exhaustion or otherwise, the ownership of the refuse material reverts to the lessor. Therefore, a question was raised in the minds of these operators: Why should I assume the expense of such pro¬cedure when I have no assurance that I will benefit by the future processing and sale of these fine sizes? Under present conditions, the answer to this question is not one of choice but of necessity, as restrictions imposed by legislation make it mandatory on operators of preparation plants to take necessary steps to properly treat silt-laden waters before permitting them to enter the streams. By reason of these restrictions, the disposal of fine sizes becomes a secondary_ rather than a primary operating con sideration, and the procedure for disposing of this refuse becomes a matter of choice governed principally by topographical and geographical conditions. METHODS OF HANDLING REFUSE There are three principal methods of handling and disposing of fine-size refuse; namely :

Jan 1, 1946

By F. X. Spiegel, D. Bardos, Paul A. Beck

Ti6NileSi7)G is known to be cubic, with 116 atoms in the unit cell. In the present work four new G sili-cides were found with other transition elements and five G germanides. The titanium-group elements are very efficient in forming G phases. The vanadium -group elements are somewhat less efficient, and the chromium-group elements do not form any. Cobalt can replace nickel in most cases, but it is somewhat less efficient. Iron was not found to form any G phases. Germanium is somewhat less efficient than silicon. The (TiNiSi)E phase has been previously identified by Westbrook. However, its crystal structure has not been determined. In the present work the E phase was found to have an orthorhombic unit cell with lattice parameters a. = 7.02, bo = 5.18, co = 11.11A. A large number of other E phases were found at the same stoicheometric ratio in ternary systems of silicon and germanium with transition elements. Lattice parameters similar to those for TiNiSi were measured. The number of atoms per unit cell is estimated at 30 to 36. The vanadium-group elements are somewhat more efficient in forming the E phase than the titanium-group elements. Chromium-group elements were not found to form any E phases. Cobalt is somewhat less efficient than nickel, and iron is less efficient than cobalt. Germanium is not as efficient as silicon. ThE ternary silicide designated as G-phase was first identified by Beattie and versnyder1 and by Beattie and Hagel2 at the approximate composition TiNi2Si. Westbrook et al.&apos; gave the composition as Ti2Ni7Sis. This phase was found to be fcc with a. = 11.201A and 116 atoms per unit cell. Beattie4 and more recently independently Hladishevskii, Kripyakevich, Kuzma, and Teslyuk5 were able to show that this structure is isotypic with MgeSi7CuLe and Th6Mn23. The latter structures had been determined by Florio, Rundle, and snow,&apos; Nagorsen and Witte,7 and Bergman and Waugh.8 According to the crystal structure, Ti8Ni6Si7 may be considered as the ideal composition. The Russian investigators5 identified six additional ternary phases isotypic with Ti6Ni6Si7, in which titanium is replaced by Mn, V, Nb, Ta, Zr, and Hf, and one, namely MneNil6Ge7, in which germanium replaces silicon. They also found that Cr6Ni6Si7, which does not occur as a ternary phase, can be stabilized by replacing 1 at. pct of the Cr by V, Mn, or Ta. Another ternary silicide was found by Westbrook et al.3 at the composition TiNiSi, and it was designated by them as the E phase. The crystal structure of this phase has not been deter-

Jan 1, 1963

By Walter R. Hibbard, Harold Margolin

The effect of ten ternary additions on the aging of a Cu-Ag alloy was measured by X ray, microstructure and hardness. A supersaturated copper-rich transition structure was found. The effect of the ternary element was related to differences between transition and precipitate lattice parameters and analogies with solution and strain hardening. IN addition to the prerequisite of diminishing solid solubility with falling temperature, the theory of coherency hardening1 proposes that the principal source of hardening during precipitation is strain caused by coherency between the matrix and precipitate. For a given system greater coherency hardening would result from lengthening the period of coherent growth and/or increasing the number of nuclei, other things remaining equal. However, the hardness change during aging is a function of a number of phenomena in addition to coherency hardening, such as dispersion hardening, loss of coherency, solute depletion, matrix recovery or recrystal-lization, coalescence, and their relative time sequences. The present investigation was undertaken to study the effect of ternary additions on the age-hardening of Cu-Ag alloy. For this purpose a series of alloys were made containing as ternary constituents Mg, Al, Si, P, Mn, Ni, Zn, As, In, and Sb. These elements were added to a master 5 wt pct Ag in Cu alloy in such amounts as to obtain alloys listed in Table II containing the following approximate atomic percentages: 96 pct Cu, 3 pct Ag, 1 pct ternary addition. A 97 atomic pct Cu, 3 atomic pct Ag alloy was used as a comparison standard. There have been numerous investigations of age-hardening in Cu-Ag alloys2-lo but few of ternary Cu-Ag alloys. Pfister and Weist" found that 1 wt pct Ni reduced the solubility of Ag in Cu above 600 °C and that the rate of precipitation was slower than in polycrystalline Cu-Ag alloys of similar silver content. More recently Hodge, Jaffee, Dunleavy, and Ogden12 investigated the effect of ternary additions of Mg, Li, P, Cd, Zn, Zr and Be on strength properties of Cu-Ag alloys. Mg, Cd, and P were found to increase strength in the aged and cold-worked condition. Experimental Procedure Charges weighing 7.5 lb were melted in a closed carbon crucible under a reducing atmosphere* of nitrogen and hydrogen. A Durville-type casting procedure with a hot-top arrangement was used to obtain a sound casting, 2x2x43/4 in. Prior to rolling and annealing of the ingots, a trial solution anneal of rolled sections of the hot-top portions indicated that at 780°C melting was avoided except for the Cu-Ag-Sb alloy. This alloy could not be produced as a single phase within the limits of temperature control. i 3" to 5oC, since melting occurred at 64O °C, and below this temperature precipitation was

Jan 1, 1952

By V. C. Allison

Large-scale testing of the explosibility of coal dust as conducted by the Bureau of Mines in its Experimental Mine involves a large initial investment, and a high charge for maintenance and conduct of the test; in addition the work is necessarily slow because of the time required for the preparntion of the tests and the cleaning and repairing of the mine after each test. These tests have been made along practical mining lines that admit of a range of mixtures of dust varying from 5 to 10 per cent. and with gas as low as 0.5 per cent. increments. Because of the time and expense involved, efforts have been made to devise a type of gallery for laboratory use in which the results obtained in the Experimental Mine may be correlated as an aid in a study of dusts, the explosibility of which might be approximately determined quickly and at a minimum of expense. The explosibility of coal dust has been studied by a number of European investors, using small laboratory devices; among these may be mentioned the experiments conducted by Galloway, Vital, Hall and Clark, Abel, Mallard and Chatelier, Thorpe, Bedson and Widdas, Engler, Holwartz and Meyer, and Taffanel, results of whose experiments have becn reviewed by the Bureau of Mines.&apos; The Bureau has conducted many tests with the Frazer-Cle1ncnt5 apparattus, which gives the pressures set up when the dust cloud within is ignited with a platinum coil or tube, heated to different temperatures, but for these tests the sample must be especially prepared as to size (200 mesh) and must be dry. Need for a Dust-testing Apparatus An attempt has been made to design an apparatus that may be used for checking and correlating the expcrimental tests. The first design was a wooden gallery, 8 by 10 in., inside cross section, and 12 ft. long, and having a number of strips along each side for creation of turbulence. The wooden gallery did not get beyond its period of calibration; it mas difficult to make the gallery sufficiently tight, for it was necessary that the top be removable in order that the gallery could be cleaned. In the use of the wooden gallery, however, sufficient operating data were obtained to be a guide in the design of a steel gallery having a circular cross-section. One of the features was a flap valve, at the closed end of the gallery, that would open inwardly thus preventing a reduced pressure within, caused by the cooling of the gases of combustion, and the explosions propagated much better than when the valve was not used; another feature was the determining of the best method for getting a cloud of dust simultaneously in all parts of the gallery, which was accomplished by the use of the concussion wave of a small quantity of powder or by the use of compressed air.

Jan 1, 1927

By H. I. Aaronson

Isothermally formed plates of proeutectoid a, lengthen at approximately the rates predicted by the Zener-Hillert equation, indicating that their lengthening kinetics are controlled by the volume diffusion of chromium in the ß matrix. Solution annealing treatments in the vicinity of the transus introduce a second mode of transformation, in which the lengthening rate is at least 1.8 x 104 faster than predicted by this equation. Little or no volume diffusion appears to accompany the latter transformation. The Presence of oxygen is evidently a Prerequisite for the occurrence of this reaction. X HE effects of thermal history prior to the initiation of transformations which proceed by nucleation and diffusional growth are currently evoking considerable interest. The rate of nucleation (but not the rates of growth) of pearlitel and of bainite,2 and the over-all rates of aging reactions in Al-cu3 and Al-si4 alloys have been shown to be appreciably dependent upon thermal history in the solid-solution region"&apos; or in the two-phase region prior to the onset of pre~ipitation.3,4 In none of these reactions, however, was the transformation mechanism changed by variations in the temperature-time path used to reach the reaction temperature. Preliminary experiments reported by M. K. McQuillan5,8 and a systematic investigation by Farrar and Margolin7 have disclosed that the transformation behavior of hypoeutectoid Ti-Cr alloys is considerably more sensitive to thermal history. Qualitative evidence strongly suggests that not only the rate of nucleation but also the rate of growth and even the mechanism of the ß — a reaction can undergo remarkable changes when a solution annealing treatment in the vicinity of the ß/a +ß, or transus temperature, is interposed between a high-temperature solution anneal (conventionallq at 1000°C) and the isothermal reaction treatment. The present investigation was undertaken in an attempt to ascertain the nature and origin of these effects. Study of the changes in the kinetics and morphology of the ß - a, reaction produced by varialtions in thermal history was the primary means employed for this purpose. EXPERIMENTAL PROCEDURE The compositions of the alloys used in this in~esti~ation are given in Table I. These alloys were homogenized for 5 days at 1050° C in evacuated (2 x 10 -5 mm of Hg), zirconium-gettered fused quartz capsules. The capsules themselves were enclosed in a porcelain chamber evacuated with a mechanical pump during the homogenization anneals. Upon completion of homogenization, the alloys were cooled to room temperature and then reheated to 550°C for 3 1/2 days in order to transform the alloys to a finely divided mixture of a and TiCr2, and thus provide an approximately constant initial mi-crostructure. Individual specimens were sealed in evacuated and internally gettered Vycor capsules and heat treated as previously described.8,9 EXPERIMENTAL RESULTS Ti-10.64 Pet Cr. This investigation was largely performed on the 0.64 pet Cr alloy. The "base"

Jan 1, 1962

By N. P. Goss

Asterism appearing in X-ray Laue diagrams is an extremely sensitive index of changes in the internal structures of individual grains of polycrystalline metals. It indicates the existence of various forms of subboundary structure or subdivision within the grain. The present viewpoint is that the grain is made up of lattice blocks having substantially the same size and shape.l-4 When these blocks all assume exactly the same orientation, the crystal is perfect and asterism is absent. Cleaves and Thompson5 observed that the hardness of iron is virtually constant over a range of grain sizes. It is quite possible that the subboundary structure caused this, and that the latter is just as important as grain size itself. While the experiments reported here are not conclusive, they do support this viewpoint. Metals can, under certain conditions, be prepared entirely free from asterism, but this preparation does not necessarily require long heating or slow cooling, as will be shown here. In this paper a distinction is made between mosaic and distorted grain structures but the difference is only a matter of degree. In a previous paper9 it was shown that the grains can become distorted even during heat-treatment. The block structure exists inherently, even in a perfect crystal; the size and shape of these crystallites, or lattice blocks, varies, depending upon a number of factors. Goetz, for example: has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-l4 to 10-l5 c.c., or 10-15 cm. in size. These crystallites, or blocks, appear to survive the most drastic cold-working, for it has been shown, and more elaborately by Wood&apos;s recent work," that cold-working cannot reduce the size of these crystallites smaller than of the order 10-5 cm. The interesting correlation brought out by the experiments of Goetz and Wood is that the block size after severe cold-working is of the same order of magnitude as the groups that formed in the metal just before crystallizing from the molten state. The work of Ewald and Rennenger17 and the now classical experiments of Darwin and James12,13 all strongly suggest the existence of a periodic structure of crystal. lites smaller than the grain itself. Related to this effect is the appearance of veinlike markings in the microstructures. Ammer-man and Kornfeld,16 in their experiments, did not observe any evidence of veining in specimens of alpha iron annealed below A3 and believed that veining was not due to impurities in the iron, as Northcott16 suggested; veining was observed by them only in specimens annealed above A3. Hanemann,16 Schrader and Tangerding found that annealing in hydrogen did not diminish veining and so it could not be caused by oxides. They concluded that veining was due to a slight difference in the orientation of ferrite lattice blocks. This viewpoint is well supported by the evidence presented here.

Jan 1, 1941

By N. P. Goss

Asterism appearing in X-ray Laue diagrams is an extremely sensitive index of changes in the internal structures of individual grains of polycrystalline metals. It indicates the existence of various forms of subboundary structure or subdivision within the grain. The present viewpoint is that the grain is made up of lattice blocks having substantially the same size and shape.l-4 When these blocks all assume exactly the same orientation, the crystal is perfect and asterism is absent. Cleaves and Thompson5 observed that the hardness of iron is virtually constant over a range of grain sizes. It is quite possible that the subboundary structure caused this, and that the latter is just as important as grain size itself. While the experiments reported here are not conclusive, they do support this viewpoint. Metals can, under certain conditions, be prepared entirely free from asterism, but this preparation does not necessarily require long heating or slow cooling, as will be shown here. In this paper a distinction is made between mosaic and distorted grain structures but the difference is only a matter of degree. In a previous paper9 it was shown that the grains can become distorted even during heat-treatment. The block structure exists inherently, even in a perfect crystal; the size and shape of these crystallites, or lattice blocks, varies, depending upon a number of factors. Goetz, for example: has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-l4 to 10-l5 c.c., or 10-15 cm. in size. These crystallites, or blocks, appear to survive the most drastic cold-working, for it has been shown, and more elaborately by Wood&apos;s recent work," that cold-working cannot reduce the size of these crystallites smaller than of the order 10-5 cm. The interesting correlation brought out by the experiments of Goetz and Wood is that the block size after severe cold-working is of the same order of magnitude as the groups that formed in the metal just before crystallizing from the molten state. The work of Ewald and Rennenger17 and the now classical experiments of Darwin and James12,13 all strongly suggest the existence of a periodic structure of crystal. lites smaller than the grain itself. Related to this effect is the appearance of veinlike markings in the microstructures. Ammer-man and Kornfeld,16 in their experiments, did not observe any evidence of veining in specimens of alpha iron annealed below A3 and believed that veining was not due to impurities in the iron, as Northcott16 suggested; veining was observed by them only in specimens annealed above A3. Hanemann,16 Schrader and Tangerding found that annealing in hydrogen did not diminish veining and so it could not be caused by oxides. They concluded that veining was due to a slight difference in the orientation of ferrite lattice blocks. This viewpoint is well supported by the evidence presented here.

Jan 1, 1941

By Robert Maes, Robert de Strycker

The Cu-Sn-As systeM was studied in the region near the Cu-42 and (214-As binary diagrams, where reactions in the solid state appear, resulting from the decomposition of the y(Cu-Sn) phase and from the formation of the 7 phase (Cu,As). The techniques used were microscopic observation, thermal analysis by dilatometry, and X-vay diffraction. The formation of the 7 phase gives rise to a ternavy pevitectoid veaction; the decomposition of the y phase gives rise to five transitional reactions. The temperatures of almost all these reactions could be determined; in the most favorable cases , the accuracy of this determination was of 11.5-C. The 7 phase is stabilized by tin additions, the arsenic atoms being replaced by tin atoms up to 35 pct; this has allowed the preparation of pure j) phase and the confirmation, by extrapolation, of the conrposition of this compound in the Cu-As diagram. In the first part of this work, the solidification reactions in the Cu-Sn-As phase diagram were studied. In the copper corner, the structure of the alloys presented the evidence of reactions in the solid state: on the one hand, all the alloys containing the y phase of the Cu-Sn diagram showed, under the microscope, that this phase had formed different decomposition products after complete solidification; on the other hand, the appearance of the 7 phase of the Cu-As diagram necessitated the introduction of a peritectoid formation reaction. The study of the decomposition of the y phase has been done by preparing about forty alloys that were homogeneous y at high temperature. The formation of the 7 phase has been studied by means of a few alloys with a composition near the homogeneity field of this phase at room temperature. The part of the Cu-Sn phase diagram of interest for this study is represented by Fig. 1, with the phase designation which will be used in the remainder of this paper; it is drawn after Hansen and Anderko.&apos; The Cu-As diagram has already been presented in Part I of this work; the significant features of this study are the existence of the arsenides CusAs and Cu5Asz, and the formation of a compound CUEAS, designated as the 7 phase, by a peritectoid reaction at about 325°C. EXPERIMENTAL METHODS The fundamental technique for the investigation of this part of the Cu-Sn-As constitution diagram was microscopic observation; the greatest part of the observed alloys has also been subjected to thermal analysis by dilatometry; a few selected alloys have then undergone an X-ray analysis by powder diffraction. Alloy Preparation. The alloys were prepared from the same products as in Part I of this study: cathode copper, arsenic with a purity better than 99.5, and tin with a purity of 99.98. The fusion of the ternary alloys was realized from

Jan 1, 1967

By Herbert H. Kellogg

DEPOSITS of high-silica kaolinite clays occur at many places in central Pennsylvania. These white clays were formed apparently by weathering of argillaceous quartzite and limestone. Their geology, distribution and use have been reported by Leighton.1 The larger deposits have been mined from time to time, and the clay, after washing to remove coarse sand, has found use as rubber filler, foundry clay, and in white cements. In general, the clay from these deposits contains too much grit (quartz) to be useful as paper filler, and the silica content is too high to make it useful as china clay for ceramic ware. Gravity methods for the separation of quartz from these clays have failed because of the extremely fine size of the quartz grains, but by the methods of froth flotation described in this paper these sandy kaolins can be made to yield a purified kaolinite that has a chemical composition close to that of good-grade Georgia kaolins, and is free enough from grit to be used as a paper filler. As by-products of the separation, a fine (-325-mesh) sand assaying 95.5 per cent Si02, and a very fine (-3-micron) clay are produced. The possible ceramic uses of these products are being investigated at The Pennsylvania State College. EXPERIMENTAL PROCEDURE The Sample.-The clay sample used in these tests was obtained from a small mine near Tyrone, Pa. It had already been washed to remove coarse sand, and represented the finished product of this small mine and washery. Microscopic examination showed that the clay was composed almost entirely of the minerals quartz and kaolinite, and that the quartz was present mostly in particles larger than one micron, while the kaolinite particles generally were less than 20 microns in size. The kaolinite and quartz particles were physically separable by blunging the clay in water with a suitable dispersant. Preparation of Flotation Feed.-By the addition of NaOH in an amount equal to 3 lb. per ton of solids, the clay was completely dispersed in water. Flotation feed was prepared by allowing a dispersed suspension (10 per cent solids) of the clay to stand for the period of time required for a 2.5-micron particle of quartz to settle from the top of the container to the bottom. After this settling period the suspension was decanted from the settled solids. The settled solids were redispersed in water and the separation was repeated once. The two fine fractions were then combined. Thus the clay was divided into a fine and a coarse fraction by size separation at approximately 2.5 microns.* The fine fraction was found to have a considerably lower sand content than the raw clay (Table I), and was not treated further. The coarse fraction formed the flotation feed for all the tests described in this paper.

Jan 1, 1945

The Pinto Valley, Arizona, plant of Cities Service Company is one of the newest copper producers in the United States, having started production in 1975. It is located a few miles west of Miami, Arizona, on the site of the Castle Dome Mine, a World War II operation which was shut down and its mill later moved and renamed the Copper Cities plant. The Pinto Valley concentrator uses six 18 ft (5. 5 m) diameter by 21 ft (6.4 m) long, 4000 hp, single-stage ball mills, taking crushed ore from four 7 ft (2. 13 m) standard and eight 7 ft shorthead crushers. It has a design capacity of 40,000 stpd but has higher tonnage capability for an expanded concentrator. The copper porphyry-ore is mined by two 15 yd and one 20 yd shovels (11.5 and 15.3 cu m) and is transported to the primary crusher by 150-ton trucks. The dump pocket is relatively shallow (14 ft or 4. 27 m deep); and because of the width necessary for the 150-ton trucks, it was designed to use the ore itself instead of manganese steel as an abrasion- resistant lining, although a heavy steel cap protects the dump pocket top edge. The pocket has a capacity of 300 tons of ore. Water sprays under the dumping positions direct a fog toward the truck being dumped for excellent dust control. Breaking of oversize is done by a hydraulic impact breaker mounted on a hydraulically operated articulated arm situated at the side of the dump pocket. Again because of the shallow pocket, no splitter is used to protect the spider of the 60 in. by 89 in. Traylor gyratory crusher, which is equipped with a hydroset mechanism. Crushed ore at 8 in. (203 mm) drops into the 360 st surge chamber lined with AR plate and then is fed directly to the 60 in. (1.52 m) stock- pile conveyor by an 84 in. by 20 ft (2. 13 m by 6.1 m) four-speed apron feeder at a rate of up to 4000 stph. Early in 1977, Cities Service will replace the four -speed electric drive with a hydraulic pump and motor with infinitely variable speed. They are also studying the replacement of the apron feeder with an 8 ft wide (2.44 m) belt feeder similar to those at Similkameen and Palabora. Peak crushing capacity would then be increased to 5000 stph. The AR plate in the crushed ore pocket was installed in large, rectangular sheets which required much less embedded metal to hold it in place than would the more conventional, smaller arid square pieces of cast manganese steel. For duty in the crushed ore pocket, where wear is not severe, the AR plate is a satisfactory material. The new Palabora Figure-8 crusher also uses this design.

Jan 1, 1978

By Thomas A. Read

The internal friction of single crystals of metals is affected markedly by a variety of factors, which, according to the literature, are without influence on the internal friction of polycrystalline metals at strain amplitudes less than 10-5. For example, the internal friction of a suitably oriented zinc single crystal is multiplied by a factor of ioo when the vibration amplitude is slightly increased, and the internal friction of a copper crystal is markedly increased by the application of a stress of 30 lb. per sq. in. for one minute. In this paper it will be shown that these, together with the other phenomena associated with the damping of mechanical vibrations in metal single crystals, can be satisfactorily explained, at least qualitatively, in terms of an atomic mechanism that has been proposed for quite another purpose—that of accounting for slip in metals. The extraordinary agreement between the observed behavior of the metal single crystals and the behavior that could be predicted on the basis of this atomic mechanism leads to the belief that the latter is probably essentially correct. If this is so, it follows that valuable information about the slip process in metals may be gained from measurements of internal friction on single crystals. In this paper the results of the only study to date on the damping of mechanical vibrations in single crystals of metals mill be presented. Experimental Procedure The internal friction of a material is a measure of the rate at which the energy of mechanical vibrations is converted into heat. The measure of internal friction used in the present paper is the decrcment A, which is defined as the fraction of the energy of vibration lost per half cycle. The measurements described here were made for longitudinal oscillations at a frequency of 33.5 kc. for the copper crystals, and at a frequency of 39 kc. for the zinc crystals. The method used is that of the composite piezoelectric oscillator. The single-crystal specimens are in the form of circular cylinders M in. in diameter and I 1/2 to 21/2 in. long. The crystal rods are waxed in a V-block and sawed to the proper length with a fine jeweler&apos;s saw. The ends of the specimen are ground flat, and one end is cemented with a very thin film of beeswax and rosin to the end of an x-cut quartz rod which is 1/4 in. in diameter and 3 in. long. The length of the specimen rod is determined by the condition that its natural frequency for longitudinal vibration be the same as that of the quartz rod, within 0.5 per cent. The lengths of the specimens are thus different for different orientations of the cylinder axis with respect to the crystallographic axes. When the specimen and quartz rods are thus matched in frequency the adhesive is at a node of stress, and it has been shown experimentally that under these circumstances

Jan 1, 1941

By Thomas A. Read

The internal friction of single crystals of metals is affected markedly by a variety of factors, which, according to the literature, are without influence on the internal friction of polycrystalline metals at strain amplitudes less than 10-5. For example, the internal friction of a suitably oriented zinc single crystal is multiplied by a factor of ioo when the vibration amplitude is slightly increased, and the internal friction of a copper crystal is markedly increased by the application of a stress of 30 lb. per sq. in. for one minute. In this paper it will be shown that these, together with the other phenomena associated with the damping of mechanical vibrations in metal single crystals, can be satisfactorily explained, at least qualitatively, in terms of an atomic mechanism that has been proposed for quite another purpose—that of accounting for slip in metals. The extraordinary agreement between the observed behavior of the metal single crystals and the behavior that could be predicted on the basis of this atomic mechanism leads to the belief that the latter is probably essentially correct. If this is so, it follows that valuable information about the slip process in metals may be gained from measurements of internal friction on single crystals. In this paper the results of the only study to date on the damping of mechanical vibrations in single crystals of metals mill be presented. Experimental Procedure The internal friction of a material is a measure of the rate at which the energy of mechanical vibrations is converted into heat. The measure of internal friction used in the present paper is the decrcment A, which is defined as the fraction of the energy of vibration lost per half cycle. The measurements described here were made for longitudinal oscillations at a frequency of 33.5 kc. for the copper crystals, and at a frequency of 39 kc. for the zinc crystals. The method used is that of the composite piezoelectric oscillator. The single-crystal specimens are in the form of circular cylinders M in. in diameter and I 1/2 to 21/2 in. long. The crystal rods are waxed in a V-block and sawed to the proper length with a fine jeweler&apos;s saw. The ends of the specimen are ground flat, and one end is cemented with a very thin film of beeswax and rosin to the end of an x-cut quartz rod which is 1/4 in. in diameter and 3 in. long. The length of the specimen rod is determined by the condition that its natural frequency for longitudinal vibration be the same as that of the quartz rod, within 0.5 per cent. The lengths of the specimens are thus different for different orientations of the cylinder axis with respect to the crystallographic axes. When the specimen and quartz rods are thus matched in frequency the adhesive is at a node of stress, and it has been shown experimentally that under these circumstances

Jan 1, 1941

By Herbert H. Kellogg

Deposits of high-silica kaolinite clays occur at many places in central Pennsylvania. These white clays were formed apparently by weathering of argillaceous quartzite and limestone. Their geology, distribution and use have been reported by Leighton.1 The larger deposits have been mined from time to time, and the clay, after washing to remove coarse sand, has found use as rubber filler, foundry clay, and in white cements. In general, the clay from these deposits contains too much grit (quartz) to be useful as paper filler, and the silica content is too high to make it useful as china clay for ceramic ware. Gravity methods for the separation of quartz from these clays have failed because of the extremely fine size of the quartz grains, but by the methods of froth flotation described in this paper these sandy kaolins can be made to yield a purified kaolinite that has a chemical composition close to that of good-grade Georgia kaolins, and is free enough from grit to be used as a paper filler. As by-products of the separation, a fine (— 325-mesh) sand assaying 95.5 per cent SiO2, and a very he (—3-micron) clay are produced. The possible ceramic uses of these products are being investigated at The Pennsylvania State College. Experimental Procedure The Sample.—The clay sample used in these tests was obtained from a small mine near Tyrone, Pa. It had already been washed to remove coarse sand, and represented the finished product of this small mine and washery. Microscopic examination showed that the clay was composed almost entirely of the minerals quartz and kaolinite, and that the quartz was present mostly in particles larger than one micron, while the kaolinite particles generally were less than 20 microns in size. The kaolinite and quartz particles were physically separable by blunging the clay in water with a suitable dispersant. Preparation of Flotation Feed.—By the addition of NaOH in an amount equal to 3 lb. per ton of solids, the clay was completely dispersed in water. Flotation feed was prepared by allowing a dispersed suspension (10 per cent solids) of the clay to stand for the period of time required for a 2.5-micron particle of quartz to settle from the top of the container to the bottom. After this settling period the suspension was decanted from the settled solids. The settled solids were redispersed in water and the separation was repeated once. The two fine fractions were then combined. Thus the clay was divided into a fine and a coarse fraction by size separation at approximately 2.5 microns.* The fine fractioh was found to have a considerably lower sand content than the raw clay (Table I), and was not treated further. The coarse fraction formed the flotation feed for all the tests described in this paper. A size separation of this type can be

Jan 1, 1947

By Ronald C. Koo

THE effect of grain size on the mechanical properties of the bcc metals has been a subject of intensive theoretical and experimental study.&apos;-l5 Quantitative relationships have been established experimentally between yield stress and grain size and between the ductile-brittle transition temperature and grain size in a number of metals.6"15 Much significance has therefore been attached theoretically to the grain size dependence. In all these experiments, different grain sizes were always achieved by annealing specimens at various temperatures. The implicit assumption was that any change in the dislocation substructure or in the distribution of impurities which might occur simultaneously with the production of various grain sizes had only a negligible effect on the mechanical properties. The validity of this assumption, however, is questionable. transformation in iron-nickel alloys is actually an extraneous phenomenon due to inadvertent compositional changes in the martensite if the heating rate is not sufficiently rapid. This complication can be avoided by up-quenching for the reversal treatment,5 and then the stabilization does not appear. Clearly, the lattice imperfections and strengthening produced by the reverse transformation are not responsible for the marked stabilization which has been observed by other investigators in these alloys. Data will be presented in this note to show that, at least in recrystallized tungsten of commercial purity, the difference in the ductile-brittle transition temperature of specimens annealed at various temperatures is more a result of a variation in the distribution of impurities rather than of the difference in grain size produced by the anneal. Ductile-brittle transition temperatures in tension were determined on powder-metallurgy tungsten specimens recrystallized at various temperatures. Tensile specimens having a gage length of 1.50 in. and gage diam of 0.18 in. were recrystallized at 1450°, 2000°, 2350°, 2550°, 2750°, or 2800" for 30 min in a vacuum furnace at a pressure of 1 x 10"5 mm of Hg and then tested at a constant extension rate of 8 x 10 per sec in an argon atmosphere from 100" to 800". Typical quantitative analyses of impurities are given in the Table. These results show that, within the precision of the analyses, see Table, annealing did not result in any detectable change in the impurity contents of the specimens, nor was there any detectable difference in purity between specimens having large differences in grain size annealed at the same temperatures . The results of the tensile tests yielded three distinct ductile-brittle transition curves approximately 225&apos; apart. As shown in Fig. 1, data of specimens annealed at 1450°C and those of specimens annealed at 2000°C (O) fell on Curve A. Data of specimens annealed at 2350" and 2550°C fell on Curve B, and those of specimens annealed at 2750" and 2800°C fell on Curve C. The decrease in ductility with increase in annealing temperature became so pronounced that one third of the specimens annealed at 2750" and two thirds of the specimens

Jan 1, 1963

By Herbert H. Kellogg

Deposits of high-silica kaolinite clays occur at many places in central Pennsylvania. These white clays were formed apparently by weathering of argillaceous quartzite and limestone. Their geology, distribution and use have been reported by Leighton.1 The larger deposits have been mined from time to time, and the clay, after washing to remove coarse sand, has found use as rubber filler, foundry clay, and in white cements. In general, the clay from these deposits contains too much grit (quartz) to be useful as paper filler, and the silica content is too high to make it useful as china clay for ceramic ware. Gravity methods for the separation of quartz from these clays have failed because of the extremely fine size of the quartz grains, but by the methods of froth flotation described in this paper these sandy kaolins can be made to yield a purified kaolinite that has a chemical composition close to that of good-grade Georgia kaolins, and is free enough from grit to be used as a paper filler. As by-products of the separation, a fine (— 325-mesh) sand assaying 95.5 per cent SiO2, and a very he (—3-micron) clay are produced. The possible ceramic uses of these products are being investigated at The Pennsylvania State College. Experimental Procedure The Sample.—The clay sample used in these tests was obtained from a small mine near Tyrone, Pa. It had already been washed to remove coarse sand, and represented the finished product of this small mine and washery. Microscopic examination showed that the clay was composed almost entirely of the minerals quartz and kaolinite, and that the quartz was present mostly in particles larger than one micron, while the kaolinite particles generally were less than 20 microns in size. The kaolinite and quartz particles were physically separable by blunging the clay in water with a suitable dispersant. Preparation of Flotation Feed.—By the addition of NaOH in an amount equal to 3 lb. per ton of solids, the clay was completely dispersed in water. Flotation feed was prepared by allowing a dispersed suspension (10 per cent solids) of the clay to stand for the period of time required for a 2.5-micron particle of quartz to settle from the top of the container to the bottom. After this settling period the suspension was decanted from the settled solids. The settled solids were redispersed in water and the separation was repeated once. The two fine fractions were then combined. Thus the clay was divided into a fine and a coarse fraction by size separation at approximately 2.5 microns.* The fine fractioh was found to have a considerably lower sand content than the raw clay (Table I), and was not treated further. The coarse fraction formed the flotation feed for all the tests described in this paper. A size separation of this type can be

Jan 1, 1947