Search Documents

By J. E. Burke

Recent investigations have elucidated many of the phenomena of the grain growth process, but have also revealed some conflicting and unexplained results. Beck and his co-workers 1,2,3 have shown that grain growth continues with continued heating at one temperature until the average grain size approaches the thickness of the specimen. Plotting the logarithm of the average grain diameter, D, against the logarithm of the annealing time, t, they find the straight line relationship given by the equation: D = Ktm [,] with possible small deviations at short annealing times. K and n are constants at constant temperature. On the other hand, Wa1ker4 finds that, in alpha brass) the rate of growth falls off more rapidly than indicated by Eq i after long annealing, so that an equilibrium grain size is approached. Burke5 showed, using Walker's data, that time and temperature for grain growth are apparently related through an activation energy, H, according to the relationship: ] where h and tz are the annealing times necessary for the average grain size to increase from Do to D at temperatures T1 and T2 and R is the gas laws constant. In the case quoted, H had the value 60,000 cal per mol. The apparent validity of this relationship, at least up to 700°C, and the approximate value of H were later confirmed by Beck3 The results obtained by Beck Kremer, Demer and Holzworth2 for aluminum and aluminum-magnesium alloys could not be satisfied by such a relationship, since the slope of the isothermal curves increased with increasing temperature. These data indicate and Beck, Holzworth and HuV ater demonstrated expcrimentally that the only apparent factor controlling the rate of grain growth at constant temperature is the grain size. While many of the phenomena have been elucidated, a reasonably quantitative explanation of the process is lacking. There exists uncertainty even as to the primary driving force for grain growth, although there is a considerable body of indirect evidence that the interfacial energy of the grain boundary is responsible.7,8,io Making implicit use of this assumption, several authors14,16 have pointed out that grain boundaries should migrate toward their center of curvature. Harker and Parkerg have advanced this concept furthest, and show that one can expect grain boundary migration to occur only when the grain faces are curved, or when they meet at non-equilibrium angles. When the face is curved toward a grain A, for example, the atoms in the surface of grain B, on the other side of the boundary7 are on the average more surromded by the atoms of their lattice than the atoms on the surface of grain A. Because of thermal motion, the atoms at the interface will sometimes be attached to grain A and

Jan 1, 1949

By R. T. Pepper

DURING an investigation into the effect of heat-treatment on the creep properties of the magnesium alloy ZW1, (1 pct Zn, 0.6 pct Zr), the previously published methods of final polishing were found to be unsatisfactory. A new diamond-polishing technique has been developed to facilitate the study of fine precipitates in this and other magnesium alloys, and is described in this note. The sectioning and coarse grinding techniques are those of Fox and Hall,' and Hess and Cieorge.' Pre- liminary mechanical polishing is done with 6-µ, and 1-µ( grades of diamond compound on 'Microcloth' using a lubricant of 'Hyprez' oil. When the conventional technique is used with a 1/4- µ diamond wheel for the final polishing of magnesium alloys, scratching is likely to result from the abrasive action of the 'Microcloth' nap on the soft metal surface. This problem has been overcome by the use of a cream on the wheel in order to separate the specimen surface from the polishing cloth. To prepare this cream, a solution of 6-ml tri-ethanolamine in 75-ml water is stirred into 12.5 g stearic acid at a constant temperature of 80° to 90°C. The cream is allowed to cool, and is then 'whipped' to a smooth consistency with 100-ml 'Hyprez' oil. Before polishing, the diamond loaded 'Microcloth' is moistened with a few drops of 'Hyprez' oil, then a small amount of cream is worked into the nap. For the best results a wheel speed of 500 rpm should be used for polishing, and the specimen should be held by hand with a light pressure while being rotated in the opposite direction to the wheel. After polishing it is necessary to swab the specimen thoroughly in methylated spirits to remove residual cream and oil from the surface in order to avoid uneven etching and drying stains. Fig. 1 shows the surface finish obtained on a specimen by polishing on a 1/4- ° diamond wheel using the cream, and Figs. 2 and 3 the precipitate observed in ZW1 after polishing, and etching for two seconds in nitric acid 15 pct in ethylene glycol. This new diamond-polishing technique has made a valuable contribution to the programme of metal-lographic research on ZW1 and has become a routine laboratory practice for other low alloy content magnesium alloys.

Jan 1, 1961

By George Smith

THE Secretary of the Interior in his recent report to the President has defined the new public-land policy, which is in fact "but a new application of an old policy." His words may be more acceptable on this subject of land classification than the repetition of phrases which have served some of us for several years. Secretary Lane says of the past: "Congress has always been most generous as to the disposition of the national lands. . . . There was land for all, and it was the government's glad function to distribute it and let those profit who could. . . . And this generous donor was not so petty as to discriminate between kinds of lands, the uses to which they could be put, or the purposes which those might have who got them. Land is land, save when it contains minerals; this was roughly the broad principle adopted. To classify was a task too difficult or not worth while. The lands would classify themselves when they arrived in individual ownership. And so the door was opened for monopoly and for fraud. Of the reaction and the evolution of a new policy, the Secretary continues: "A reaction was inevitable. If lands were to be withdrawn from public service, why might not the government do the withdrawing itself? The old philosophy that `land is land' was evidently unfitted to a country where land is sometimes timber and sometimes coal; indeed, where land may mean water-water for tens of thousands of needy neighboring acres. For the lands of the West differ as men do, in character and condition and degree of usefulness. We had not recognized this fact when we said `land is land.' Lands fitted for dry farming and lands that must forever lie unused without irrigation; lands that are worthless save for their timber; lands that are rich in grasses and lands that. are poor in grasses; lands underlain with the non-precious minerals essential to industry or agriculture; lands that are invaluable for reservoir or dam sites these varieties may be multiplied, and each new variety emphasizes the fact that each kind of land has its own future and affords its own opportunity for contributing to the nation's wealth.

Jan 6, 1914

By C. R. Fulton

The idea of making permanent magnets by sintering is not a new one, but until the introduction of the iron-nickel-aluminum permanent-magnet alloys there was little need for such a process. Permanent-magnet alloys in use up to the time of this development could be forged and machined to the exact size or shape required without too much difficulty. These new Fe-Ni-A1 alloys, which have become known as Alnico in this country, soon became very popular because of their superior magnetic properties, but when they were made by casting they did have some disadvantages when compared with the older type of permanent-magnet steels. Among these disadvantages were the following: 1. It was almost essential that they be cast to size, since they could not be readily forged or machined. The material could be ground but this was quite expensive, particularly for small magnets in large quantities. 2. The material had a large grain size and was mechanically weak. 3. Close tolerances could not be held and on small magnets this meant grinding almost the entire magnet. Because of the brittle nature of the material, there was considerable loss due to chipping and cracking during these grinding operations. 4. Because of its high aluminum content, the molten alloy had a high surface tension. It was difficult to prevent loss of aluminum by oxidation during the melting operation. In view of these difficulties it is not hard to understand why a process for sintering alnico was developed, or why sintered alnico has come into such widespread use in recent years. It might be well to qualify this by saying that it has come into widespread use for small magnets weighing 2 oz. and less, of the type shown on Fig. I. In this size range, sintered alnico has been able to compete in price with cast alnico. Magnets larger in size, of the type shown on Fig. 2, can be made but they do not compare favorably in price with the cast material. An idea of the range of sizes that have been produced is given by Fig. 3, which shows a small magnet weighing 0.006 oz. and a large magnet with a steel insert weighing 4 lb., both made from sintered alnico. Magnets weighing more than 2 oz., however, should not be made from sintered

Jan 1, 1945

NEW MEMBERS The following list comprises the names of those persons who became members during the period Aug. 1, 1916, to Sept. 10, 1916: ALLEN, Louis M., JR., Chief Mine Sampler, Old Dominion Min: & Smelt. Co., Globe, Ariz. ATKINSON, CHESTER, Min. Engr., Asst. Supt., Smelt. Dept., Cerro de Pasco Mining Co., La Fundicion, Peru, South America. BAKER, CLAIR LINCOLN, Genl. Mgr., Mexican Dept., Amer. Smelt. & Ref. Co., 1108 Mills Bldg., El Paso, Tex. BARROWS, WALTER A., 3d, Asst. Supt., Blast Furnaces, Thomas Iron Co., Hellertown, Pa. BARTHOLOMEW, GEORGE POMEROY, Asst. Cons. Engr., Guggenheim Bros., 120 Broadway, New York, N. Y. BILLOW, ELMER E., Pres., National Supply Co., 416 NN-rest Grand Ave., Chicago, 111. BROWN, SAMUEL ROLLINS, Mill Supt., The Plymouth Cons. Gold Mines, Ltd., Plymouth, Cal.

Jan 10, 1916

By T. J. Fabiniak, R. A. Dodd, R. Balow

ALTHOUGH the (111) slip direction in pure bcc metals is well established, the information on operative slip planes is less unambiguously interpreted. So far, (110) {112), and (123) slip planes have been identified, but it is not certain whether glide on (112) and (123) really occurs or if it is composite slip on non-parallel (110) planes. The second of these possibilities is supported by the work of Chen and Maddin on niobium and molybdenum, and a subsequent analysis by these same workers of slip in bcc metals generally.3 The alternative possibility is exemplified by the work of Opinsky and smoluchowsky4 who concluded that slip in Fe-Si crystals can occur on any one of the systems {110}(111), {112}(111), and {123)(111), depending on which system the resolved shear stress is highest. Allen et alS5 also found that glide in ar iron could occur on any of these three systems, the operative system being determined principally by orientation. By an analysis of crystal rotation, slip lines, and X-ray asterism Harris6 concluded that niobium also deforms on these same systems, but if one of these glide planes does not coincide with the plane of maximum resolved shear stress, composite slip on nonparallel (110) planes may occur giving a macroscopic high indices slip plane. Earlier work on iron by Vogel and Brick reached the same conclusion.7 The analysis of slip in bcc metals is made more difficult by the fact that the slip lines may be quite wavy. In fact, the generality of wavy slip lines suggests that screw dislocations slip readily from one plane to another in the (111) zone ("pencil glide") although, as noted, it is not certain whether planes other than (110) really contribute to the slip. If planes of higher indices than {110} do operate, there is a possibility they may do so more readily at higher temperature Argon and Maloof9 observed {100}{211}(111) slip in tungsten single crystals plastically strained at low temperatures, but the results were interpreted in terms of an orientation-dependence rather than temperature-dependence. Therefore, at the present time corroborative evidence for the operation of higher indices slip planes at higher temperatures is lacking. The present results were obtained during the course of an investigation into the effect of cathode and anode surface crystallography on the prebreakdown currents of vacuum insulated devices. In the experiment of particular interest, the 1/8-in.-diam anode and the in.-diam cathode were tungsten crystals (total impurities -230 ppm) with (110) and (100) faces respectively. The faces were electrolytically planed and examined for initial perfection by plastic/carbon replicas and a study of Kikuchi lines in reflection electron diffraction patterns. They were aligned precisely parallel in an insulating holder incorporated into the electron microscope, the measured microscope vacuum being 2 x 10-5 torr, and the electrode spacing 0.01524 cm. The anode structure shown in Fig. 1 was obtained

Jan 1, 1970

By W. S. Morris

PETROLEUM'S importance in World War II can perhaps be better realized by the recitation of a few facts and figures: Gasoline needs in this war are already eighty times greater than in the last war. It takes nearly three pounds of gasoline to deliver one pound of bombs, filled with petroleum explosives, on an enemy objective. Every American soldier overseas requires an average of more than fifty gallons of petroleum products per week, with the oil used by Navy and supply ships and America's Allies boosting the consumption of oil per soldier to an even higher figure. Every oil well in the United States now must produce each day an average of four barrels of oil for war and combat jobs. More than fifty million gallons of gasoline, fuel oils, lubricants, and other petroleum products are now going directly to the fighting forces every day.

Jan 1, 1945

By V. J. Decarlo, J. J. Gilman

POLISHING pure zinc differs somewhat from polishing less reactive metals. The problem is not that of finding a suitable reagent, but rather of producing the polish in such a way that the surface remains polished after it is removed from the polishing bath. In other words., the anodic film that is vital to the polishing mechanism' must be tightly adherent and nonporous. It is usually desirable that it be thin. Polishing solutions consist of proper proportions of an acid and a strong oxidizing agent. In electro-polishing, the external circuit acts as the oxidizing agent. The proportions are critical because the essential surface film must be maintained at approximately constant thickness during the polishing process. In the case of zinc, chiefly two oxidizing agents, chromic and nitric acids, have been used. The simplest polishing reagent is concentrated nitric acid. However, it has certain disadvantages. It tends to pit: an excessive amount of heat is evolved during polishing; and the oxide film that it produces is not very stable, so that the polished sur-

Jan 1, 1957

By Ira Joralemon

THE sampling of disseminated copper deposits has been described often but the method of combining assays, to give the true shape and value of the orebody as it will be mined has received less attention. As the ore mined during five or ten years at several of the great disseminated properties has averaged materially lower in grade than the published estimates, the question of the sampling and estimating of these orebodies seems timely. In this paper, attention is given particularly to factors that may cause errors in the final estimate. Sampling of diamond-drill holes, churn-drill holes, and underground workings is briefly described in the first part of the paper; then the method of combining assays to give the average grade and tonnage that will be mined is taken up in some detail. The necessity of study of the geology of the deposit and of probable costs is emphasized. Finally, the methods of calculating tonnages are outlined. DIAMOND-DRILL SAMPLING There are three main requisites for accurate diamond-drill sampling. First, the core should be removed and the hole cleaned out at the beginning of every sampling interval, usually 5 ft. (1.5 m.). After the rods are let down, water should be run through them until it becomes clear. The water must be clear before drilling starts. In this way the material knocked down from the sides of the hole by the descending rods is washed away, instead of being left to salt the sludge, sample.

Jan 2, 1922

By John Birkinbine

This piece of Carpenter crucible steel has exhibited a tensile strength of 116,000 pounds per square inch, an elastic limit of 89,170 pounds, an elongation of 25 per cent., and a reduction in area of 42 per cent. The test-specimen had a length of 2 inches between fillets, and was an inch bar reduced to an area of 0.504 square inch. This unusual tensile strength was determined before the bar had been hardened so as to show the remarkably velvety fracture here exhibited; but a piece of the same, tested after hardening, is reported to have stood a stress of 214,000 pounds per square inch. Another test-piece is said to have shown 136,000 pounds tensile strength, 97,300 pounds elastic limit, 20 per cent. elongation in 2 inches, and 40 per cent. reduction of area. Mr. Carpenter claims that this steel, containing 2.27 per cent. chromium and 1.04 per cent. carbon, can be welded like iron, and has proved most desirable,for the highest class of die-steel.

Jan 1, 1895

By C. F. Quest

THE steel industry has a definite need in its tonnage mills for a formula relating expected tensile strength to the analysis of the steel. The McWilliam-Barnes1 and other less comprehensive formulas are used for this purpose, but these formulas were designed for an analysis range that does not include the medium manganese and silicon-bearing steels. This type of steel is being produced to meet the demand for tensile strength slightly higher than that of ordinary structural steel but not high enough to justify expensive alloy steels. The purpose of this paper is to present a somewhat more compre-hensive formula based on data accumulated over a number of years by the Inland Steel Co., and to discuss the method followed in obtaining a formula to fit the data. The resultant formula admittedly is still weak in some respects, but for the expanded analysis range appears to be an improvement over the other formulas. It is hoped that with the collec-tion of more data and possible collaboration with other mills studying this problem it will be possible to work out a more nearly perfect formula. Several publications have been issued on this subject. In some, the equation type of relation was evolved while others made a combina-tion of tables and an equation. The latter include work by Campbell2,3 and Webster.4,5 Campbell classified the steels as acid and basic and applied a different formula to each. For basic steels, he used the equation: Tensile strength = 41500 + 770C + 1000P + yMn [1] y was a variable depending on the carbon and manganese content of the steel and was listed in tables, Webster investigated acid Bessemer steel and developed the equation Tensile strength = 38000 + 800C + xP + yMn [2]

Jan 1, 1940

By B. W. Frazier

At a recent meeting of the North of England Institute of Min ing and Mechanical Engineers, during a discussion upon the com pression of air, attention was called to an apparent anomaly in the phenomena attending the compression. At a subsequent meeting this apparent anomaly was explained by Prof. Herschel, and all the facts observed shown to be strictly in accordance with the laws of thermodynamics. Upon reading the report of the discussion in the published transactions of the society, it occurred to me that an attempt to determine mathematically the amounts of energy (whether in the form of heat or of work) expended and absorbed in compressing air, and causing it to perform work by expansion, might prove of use to some who have not access to any treatise upon the application of the laws of thermodynamics to the compression of air, and who have not the time or the inclination to make such application for themselves. The apparent anomaly noticed was this: If air be compressed, and at the same time, by the sufficient application of a cooling medium, kept at a constant temperature, the indicator diagrams in the

By F. W. Steadman, Charles S. Barrett

Deformation bands of surprising regularity are found in large-grained poly-crystalline copper after cold-rolling (Fig. I). Individual bands frequently are large enough to permit a determination of their orientation by means of etch pits and an optical goniometer. Measurements have been made on 21 areas in seven different grains, and these, combined with X-ray studies of nine single crystals that had been cold-rolled after mounting in a polycrystal-line block, have contributed to a better understanding of the preferred orientations in rolled copper just as similar studies have for rolled iron1 and brass.2,3 Particular attention was given to determining orientations that are stable during rolling and to the manner of fragmentation and rotation of unstable grains. The possible role of twinning was also carefully investigated. The texture of polycrystalline copper after cold-rolling is well established by the pole figures that have been plotted by Schmid and Staffelbach,4 Iweronowa and Schdanow,6 and Brick and Williamson,8 all of which are in substantial agreement. There has been some divergence in the list of individual "ideal" orientations that have been used to describe the texture by these observers and others," although the orientation (110) [II2]—that is, (110) parallel to the rolling plane and [TIP] parallel to the rolling direction—is generally recognized as the most prominent orientation and (112) [III] one of the lesser orientations. Other orientations have been given by some observers as (236) [535], (100) [00I], and (110) [00I]. The texture of copper has also been described as (I35) [533].6,7 The sum of these orientations provides a reasonable approximation to the complete pole figure, but it does not follow that these specific orientations are necessarily of fundamental significance, for the choice of indices is arbitrary, within limits. Furthermore, a detailed investigation of the ideal orientations in cold-rolled iron discloses continuous ranges of equally favored positions rather than definite positions of high stability,' and similarly Brick's observations in a single crystal of a brass2 suggest that all orientations in the range between (110) [II3] and (110) [II7] are about equally stable. Materials and Methods The material used was vacuum-cast electrolytic copper kindly supplied by L. L. Wyman, of the General Electric Co.* Slicec 1/2 in. thick and 21/2 in. square, cut from the ingot, were rolled with 50 per cent reduction per pass to final thicknesses between 0.02 and 0.04 in., and etched to develop cube-face etch pits suitable for goniometric work.8 The etch was light on some strips and deep in others.

Jan 1, 1942

By Charles S. Barrett, F. W. Steadman

Deformation bands of surprising regularity are found in large-grained poly-crystalline copper after cold-rolling (Fig. I). Individual bands frequently are large enough to permit a determination of their orientation by means of etch pits and an optical goniometer. Measurements have been made on 21 areas in seven different grains, and these, combined with X-ray studies of nine single crystals that had been cold-rolled after mounting in a polycrystal-line block, have contributed to a better understanding of the preferred orientations in rolled copper just as similar studies have for rolled iron1 and brass.2,3 Particular attention was given to determining orientations that are stable during rolling and to the manner of fragmentation and rotation of unstable grains. The possible role of twinning was also carefully investigated. The texture of polycrystalline copper after cold-rolling is well established by the pole figures that have been plotted by Schmid and Staffelbach,4 Iweronowa and Schdanow,6 and Brick and Williamson,8 all of which are in substantial agreement. There has been some divergence in the list of individual "ideal" orientations that have been used to describe the texture by these observers and others," although the orientation (110) [II2]—that is, (110) parallel to the rolling plane and [TIP] parallel to the rolling direction—is generally recognized as the most prominent orientation and (112) [III] one of the lesser orientations. Other orientations have been given by some observers as (236) [535], (100) [00I], and (110) [00I]. The texture of copper has also been described as (I35) [533].6,7 The sum of these orientations provides a reasonable approximation to the complete pole figure, but it does not follow that these specific orientations are necessarily of fundamental significance, for the choice of indices is arbitrary, within limits. Furthermore, a detailed investigation of the ideal orientations in cold-rolled iron discloses continuous ranges of equally favored positions rather than definite positions of high stability,' and similarly Brick's observations in a single crystal of a brass2 suggest that all orientations in the range between (110) [II3] and (110) [II7] are about equally stable. Materials and Methods The material used was vacuum-cast electrolytic copper kindly supplied by L. L. Wyman, of the General Electric Co.* Slicec 1/2 in. thick and 21/2 in. square, cut from the ingot, were rolled with 50 per cent reduction per pass to final thicknesses between 0.02 and 0.04 in., and etched to develop cube-face etch pits suitable for goniometric work.8 The etch was light on some strips and deep in others.

Jan 1, 1942

By John F. Elliott, Robert D. Pehlke

The rate of reaction of nitrogen with liquid iron and with binary alloys of iron and Al, Cb, Cr, Ni, O, S, Si, and W were measured. The surface active elements, oxygen and sulfur, decrease the rate markedly. The other alloying elements have very little effect on the rate except when they function as deoxidizers, The rates of absorption and de-sorption were found to be equal. Several possible reaction mechanisms which may control the rate are considered. In order to describe completely the behavior of nitrogen in steelmaking processes, the mechanisms of mass transfer between the gaseous and liquid phases, nitrogen and iron, respectively, must be understood. A kinetic study to determine the nature of these mass transfer processes was undertaken, and the results of that investigation are presented in this paper. Specifically, the study was directed toward determining the influence of alloying elements on the rates at which pure nitrogen gas at constant pressure is absorbed and desorbed by liquid iron solutions: A previous paper1 reported measurements of the equilibrium solubility of nitrogen in liquid binary iron alloys. The experimental data are presented and discussed first and then several possible rate limiting mechanisms are considered. PREVIOUS RESEARCH The results of several investigations on the rate of absorption of nitrogen by liquid iron and iron alloys have been reported.2-14 There is little agreement on the rate coefficients among these studies because of the influence of geometry on the experimental system and of the purity of the liquid iron. The rate was found to be influenced by alloying content for the binary liquid iron systems: Fe-Al,2 Fe-C,4,6 Fe-Cr,4,5,8 Fe-Mn,5 Fe-Ni,5,8 Fe-O,9,10 Fe-O,9,10 and Fe-Si.2,6,7,11 Several investigators12"15 have reported that the rate of nitrogen absorption is increased in a reducing gas mixture and decreased in an oxidizing atmosphere. A mechanism for the retardation by oxygen of the absorption of nitrogen has been described by Naeser18 as the formation of an iron oxide film at the gas-metal interface. The film slows the absorption rate until it disolves in the metal, thus permitting nitrogen to enter the liquid iron. Karwat17 discussed the influence of oxygen in terms of the formation of gaseous molecules of nitrous oxide which represent a higher energy form than the nitrogen and oxygen or the oxidizing gas and consequently constitute an energy barrier for the process. Fischer and Hoffmann10 showed that the oxygen markedly reduces the rate of absorption of nitrogen, the rate constant being one order of magnitude smaller in liquid iron containing 0.15 to 0.24 pct 0 as compared to that in melts containing 0.001 to 0.02 pct 0. Although Chipman and Murphy2 reported that the rate of absorption of nitrogen in liquid iron was essentially independent of temperature, Eklund3 found that the rate increases strongly with increasing temperature as did Kootz4 and Saito.5,6 Karnaukhov and Morozov7 also reported a large temperature coefficient, but related it to increased stirring at higher power inputs in an inductively heated system. All of the authors above have treated their results assuming that the reaction is diffusion controlled, that the surface reaction is in equilibrium with nitrogen gas, and that a "first order" reaction takes place. Karnaukhov and Morozov7 and Humbert; who studied the rate of absorption in a closed system by observing pressure changes in the system as a function of time, concluded that their results best fit a diffusion-type analysis. This was further verified by von Bogdandy, Dick, and stranski18 and Fischer and Hoffmann10 who found the initial rate of

Jan 1, 1963

By Irwin Roman

THE literature of geophysics as applied to the discovery of mineral deposits has been very extensive during the past few years,1 but there seem to be few references to the use of the method of least squares for obtaining better interpretations of the observed data .2 There seems to be a general reluctance among geologists and engineers to acquire the technique of least squares, in spite of the fact that a thorough knowledge of the theory is not necessary for the use of the method.

Jan 1, 1932

By W. C. Winegard, C. Feng, C. Elbaum

SEVERAL investigations have been made concerning the effect of oxygen on the mechanical properties of titanium 1-6= In particular, the yield strength has received considerable attention. Finlay and snyder2 report a 0.2 pet strain offset yield strength if 49 kg per sq mm in titanium containing 0.1 pct 0 and 61 kg per sq mm in titanium with 0.2 Pct 0. These results are in good agreement with those of Jaffee, Odgen, and Maykuth3 who report values of yield strength

Jan 1, 1960

DEVELOPMENT of a chemical process for the extraction of pure metals from mill concentrates or metal scrap has progressed beyond the pilot plant stage and may prove an important adjunct to present smelting and refining methods if initial commercial operations prove economically successful. Developed by the Chemical Construction Corp., the new process involves the treatment of oxide and sulphide ore concentrates by chemical methods, instead of the usual smelting and refining techniques. Several of the many applications are now scheduled for commercial use. Refiners using the new process will prepare ore concentrates by standard flotation methods, introduce the concentrate as a slurry into an autoclave along with water and an acid or ammonia. From the resulting leach solution, recovery of individual metals is made by use of suitable reducing agents. By varying conditions during treatment, different metals in the ore are produced separately as pure powders, which may be pressed into forms ready to market, or in the case of copper, extruded as rods or pipe. The reagents are generally recovered. By manipulating the variables during reduction, selective separation of nickel, and/or cobalt, and/or copper can be made simultaneously. The separation is a continuous operation. Low metal prices are not immediately in view because of the tremendous demand at this time. However, reduced metallurgical treatment costs will allow economical mining of orebodies with lower metal content, permitting increased production to meet demand. Although the practical horizon for use of the new process appears to be limitless, one factor may enter into its employment. Just how low grade a concentrate can be economically used is unknown. In addition, for present practical considerations, only metal below zinc in the electromotive series may be processed. Each commercial application requires specific technique adaptation and pilot-plant data for engineering design. A nickel-cobalt-copper process has been researched and piloted in collaboration with Sherritt Gordon Mines, Ltd., for the firm's Lynn Lake properties. In addition, processes were tailored for cobalt concentrates of Howe Sound Mining Co., and National Lead Co., in view of the urgent need for this specific metal. Major General William N. Porter, president of Chemical Construction, says of the new process, "piloting experience has shown that production cost, from ore concentrates to pure metals should be considerably below current costs." Other savings may be realized by cutting transportation and personnel costs, and by reducing the time lag between mining and pure metal from months to a matter of hours. First commercial use of the process will start sometime this summer. Chemico is slated to finish building a $2.5 million cobalt refinery for Howe Sound Mining near Salt Lake City. The plant is expected to raise world cobalt production by 40 pct. The plant will process 35 tons of 20 pct cobalt concentrates from Howe Sound's Blackbird mine near Cobalt, Idaho, daily. Yearly production is expected to reach 2000 tons of pure metal, about one half of U. S. consumption in 1950. Steps in the Howe Sound application of the process are: 1. Acid oxidation leach. 2. Filtration (residues thrown away are insoluble compounds-gangue, iron, arsenic). 3. Cementation (for Cu removal because Cu content is too low for recovery). 4. Reduction from ammoniacal solution. 5. Separation of Co and Ni as mixed metals (95 pct Co and 5 pct Ni). 6. Recovery of ammonium sulphate. Under construction at the Fredericktown, Mo., mine of National Lead is a $5 million refinery sched- [ ]

Jan 1, 1952

By M. I. Jacobson, A. S. Yue, A. E. Vidoz, F. W. Crossman

An equation governing the concept of constitutional supercooling under the combined effect of concentration and temperature gradients was used to produce platelike Al-CuAl2 eutectic composites for mechanical properties studies. Compression specimens were prepared from a single-colony Al-CuA12 eutectic composite ingot, 2 in. in diam and 12 in. long. The specirrzens were cut such that the platelets were oriented parallel, 45 deg, and perpendicular to the compression direction. Since the ingot was of eutectic composition, The aluminum-rich matrix could dissolve 5. 7 wt pct Cu in solid solution, and therefore could be strengthened by precipitation hardening. Specimens were tested at room temperature and elevated temperatures in the unidirectionally solidified, solution-treated, and solution-treated plus aged conditions. The results were compared with those for the conventionally cast and extruded specimens. For the controlled material, the highest strengths were obtained with platelets oriented parallel to the compression axis. In the unidirectionally solidified condition, 0.2 pct offset yield strength was 32,000 psi; however, this was increased to 59,000 psi by solution treatment, and further increased to 90,500 psi by solution treatment and aging. The attainment of high compressive strengths in the Al-CuAl2 eutectic composites was interpreted in terms of the buckling of elastic CuAl2 platelets in the plastically deformed a aluminum matrix. SINCE the discovery of high-strength whiskers,' scientists and engineers have made significant progress toward incorporating these whiskers into metallic matrices, forming composites for basic studies and structural application. The general procedure is to produce the whiskers first and then to bind them together with a ductile matrix. The production of whisker-reinforced composites requires tedious handling techniques,, particularly when it is desired to align the whiskers unidirectionally. Furthermore, the interfacial bond between the whisker and the matrix is frequently poor3 so that the resulting composite has strengths lower than expected. These disadvantages are generally true for any metallic composite produced by physically mixing the components. It is possible to eliminate these shortcomings by growing whiskers directly in the matrix material by eutectic solidification.4-8 In eutectic solidification, the matrix phase and a whisker phase are grown approximately simultaneously from a liquid of the same overall composition at the eutectic temperature. If the solidification process is controlled by varying the freezing rate, the temperature gradient, and the impurity content, platelike or filamentlike whiskers are produced parallel to the growth direction. The morphology of the grown-in reinforcement, i.e.. plates or rods, generally depends on the volume fraction9 of the dispersed phase present in the eutectic mixture. Since the unidirectional eutectic solidification is a one-step process, i.e., the liquid-solid transformation process, an excellent interfacial bond between the matrix and whisker is obtained. An additional advantage is that no special handling technique for whiskers is needed. In recent years, many investigators10-13 have studied the effects of growth variables on the micromorpholo-gies of binary eutectic alloys produced by controlled solidification. The study of their mechanical properties was initiated by Kraft and coworkers14-16 who found that the strength of cast A1-CuA12 eutectic alloy can be increased threefold by unidirectional solidification. In the A1-AL3Ni system, a strength of 50,000 lb per sq in, was reported for the unidirectionally solidified eutectic alloy, a value five times higher than for conventionally cast material. Thus, the unidirectionally solidified eutectics can be used as fiber-reinforced composite materials. In this paper, we shall first use an equation17 as a guide for the production of eutectic composites in general and the Al-33 wt pct Cu eutectic in particular. Experimental data supporting the theoretical prediction are given. Second, the compressive properties of the grown A1-33 wt pct Cu eutectic were thoroughly investigated in terms of platelet orientations, thermo-mechanical treatment, and temperature. The experimental data are interpreted in terms of a buckling model of fibers in elastic fiber-plastic matrix metallic composites. EXPERIMENTAL PROCEDURE Crystal Growth. The following experimental procedure was adopted for the production of controlled microstructures in the A1-33 wt pct Cu eutectic alloy. The controlled solidification was accomplished with a movable resistance-wound radiation furnace. Fig. 1 is a schematic drawing of the solidification apparatus. A water-cooled chiller was placed into a degassed high-purity graphite crucible containing the charge. Rubber stoppers wrapped with aluminum foil were used to seal both ends of the quartz tube through which a dried argon atmosphere was passed under a slight positive pressure. At both ends of the quartz tube, radiation shields were used to minimize heat loss. The quartz tube was held in place by two steel clamps and the furnace was drawn vertically by means of a steel cable against the steel truss which permits the furnace to move without touching the tube. The drive mechanism consisted of two pulleys, a counter weight.

Jan 1, 1969

By W. G. SWART

THE best estimate on reserves of iron ore in the Lake Superior district is that made, in 1920, by Mr. R. C. Allen, amounting to 2,947,225,000 tons of assured and probable ore. This includes direct- shipping or so-called merchantable ores, and those capable of beneficiation by demonstrated processes. De- ducting from this the 287,000,000 tons shipped since 1920, leaves a present reserve of approximately 2,500,- 000,000 tons, or; about 50 years' supply. The assured ore in this estimate is given as 1,560,500,000 tons, which checks Mr. Lake's estimate of 1,528,948,000 tons, or about 30 years' supply. This is not a long time in the life of the steel industry, and it can be readily appreciated that the matter is important enough to war- rant the attention it is beginning to receive. The first question that engages our attention is, What is merchantable ore? In 1902 the average of all Mesabi shipments was 56.07 per cent iron and 4.35 per cent silica. Twenty-five years later it had dropped to 51.99 per cent iron, with silica up to 7.92 per cent. It has remained around these figures for' ten or twelve years and, except for a probable rise in silica, can stay there for an indefinite period. Most of these figures I am giving cover the Mesabi Range. Including the other ranges does not change the figures greatly, and the Mesabi Range commands the situation, since it produces about 65 per cent of the total annual tonnage and, according to Mr. Allen, contains 81 per cent of the assured reserves, 50 per cent of the probable reserves, and 66 per cent of both the assured and the probable reserves.

Jan 1, 1926