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By Hugh Marriott

MANGANESE and its ores have been recently dealt with in comprehensive papers to the Iron and Steel Institute by Sir Robert Hadfield, and in a series of papers read before the A. I. M. E. at the Cleveland meeting. I have taken the opportunity of adding this mineral, to my records of the "World's Mineral Production and Consumption," as recently pub-lished in the Economist ?. The tables bring out the following significant facts: The world's production has increased by 10 per cent since 1913. India's production has increased by 3 per cent since 1.913, the supply from this source now being 31.1 per cent of the world's output. Russia is now producing at about half its pre-war rate and yields 19 per cent of the world's production. West Africa supplies 12.5 per cent of the world's total output. Brazil's present output is 2.5 times that of the pre-war period, being 11.3 per cent of the world's output.

Jan 9, 1927

F. G. SMITH.-Probably someone will ask whether I discovered why the bottoms of the large shells broke out. I did not, as a result of this investigation. An experiment was made along the lines indicated in this paper, to determine whether abnormal grains greatly affected the physical properties of brass. Two ordinary test bars were annealed for 1/2 hr. at 750° C. and physical properties determined on one. The other was covered with indentations made with a peen hammer and then reannealed. for 5 hr. at 750° C. It was found in the tensile test to be made up of large grains 1/4 to 1/2 in. in diameter. The physical properties, however, differed from those of the first bar only as much as might be expected after a 5 hr. anneal under normal conditions. It appears then that the large grains produced in this manner do not ruin the physical qualities of the brass.

Jan 12, 1919

By Albert A. Smith

The creep properties of metals have assumed increasing importance in recent years and many investigations have been made on various phases of the problem. In the past year the annual lectures of the Institute of Metals Division1 and the Iron and Steel Division2 were concerned with this subject, and are excellent reviews. For many years the creep properties of lead and lead alloys have been investigated at the Central Research Laboratories of the American Smelting and Refining Co., and it is hoped that the present paper will contribute knowledge of some of the factors that influence creep. Lead, being a metal that recrys-tallizes readily at room temperature, is an excellent material upon which to investigate creep phenomena because of the simplicity of the apparatus needed, and it might be expected that results would apply to some extent to elevated-temperature tests of other metals. Material The creep tests of this investigation were all made on high-purity lead (99.9998+ Pb) in which the only impurity that could be detected by spectrographic and chemical means was approximately 0.0001 per cent Fe. Flat strips, 0.750 in. wide by 0. 100 in. thick, were prepared by extruding 2-in. dia. cast billets at a temperature of 250°C. This gave a material of 2 to 3 mm. average grain size with a tensile strength of j.400 lb. per sq. in. when tested at a straining rate of 5 per cent per minute. With this extremely soft material, great care was necessary in handling the specimens, to avoid distortion and subsequent recrystallization. The creep tests at 30°C. were conducted in a constant-temperature room, specially built for the purpose in the basement of an office building in which there was no moving machinery, and no vibration was detectable under the most severe conditions of shock in the adjacent surroundings. The room was well insulated and heated electrically, control being by means of a de Khotinsky regulator operating a relay. Maximum temperature variation over a period of several years has been ± 1/2°C. Specimens of the extruded strip, 16 in. long, were used for test purposes with no reduced gauge section, thus eliminating any distortion due to machining. The method of clamping and supporting the specimens is shown diagrammatically in Fig. 1. The gauge marker for the measurement of extension consisted of an aluminum strip, 0.050 in. thick by 0.75 in. wide, one end of which was ground and sanded to a precise knife-edge and fastened to the specimen by suitable pins. After the strip was fastened in place a fine scratch was inscribed just below the knife-edge by means of a sharp teasing needle. Just below this gauge scratch a short vertical mark was made so that the same point could be located and read each time. Several hundred specimens have been prepared by this method, and it was found that with experi-

Jan 1, 1941

By Albert A. Smith

The creep properties of metals have assumed increasing importance in recent years and many investigations have been made on various phases of the problem. In the past year the annual lectures of the Institute of Metals Division1 and the Iron and Steel Division2 were concerned with this subject, and are excellent reviews. For many years the creep properties of lead and lead alloys have been investigated at the Central Research Laboratories of the American Smelting and Refining Co., and it is hoped that the present paper will contribute knowledge of some of the factors that influence creep. Lead, being a metal that recrys-tallizes readily at room temperature, is an excellent material upon which to investigate creep phenomena because of the simplicity of the apparatus needed, and it might be expected that results would apply to some extent to elevated-temperature tests of other metals. Material The creep tests of this investigation were all made on high-purity lead (99.9998+ Pb) in which the only impurity that could be detected by spectrographic and chemical means was approximately 0.0001 per cent Fe. Flat strips, 0.750 in. wide by 0. 100 in. thick, were prepared by extruding 2-in. dia. cast billets at a temperature of 250°C. This gave a material of 2 to 3 mm. average grain size with a tensile strength of j.400 lb. per sq. in. when tested at a straining rate of 5 per cent per minute. With this extremely soft material, great care was necessary in handling the specimens, to avoid distortion and subsequent recrystallization. The creep tests at 30°C. were conducted in a constant-temperature room, specially built for the purpose in the basement of an office building in which there was no moving machinery, and no vibration was detectable under the most severe conditions of shock in the adjacent surroundings. The room was well insulated and heated electrically, control being by means of a de Khotinsky regulator operating a relay. Maximum temperature variation over a period of several years has been ± 1/2°C. Specimens of the extruded strip, 16 in. long, were used for test purposes with no reduced gauge section, thus eliminating any distortion due to machining. The method of clamping and supporting the specimens is shown diagrammatically in Fig. 1. The gauge marker for the measurement of extension consisted of an aluminum strip, 0.050 in. thick by 0.75 in. wide, one end of which was ground and sanded to a precise knife-edge and fastened to the specimen by suitable pins. After the strip was fastened in place a fine scratch was inscribed just below the knife-edge by means of a sharp teasing needle. Just below this gauge scratch a short vertical mark was made so that the same point could be located and read each time. Several hundred specimens have been prepared by this method, and it was found that with experi-

Jan 1, 1941

By Charles R. Keyes

A COMPLETE transformation has taken place in the boras industry during the year 1908. A most remarkable factor in this radical change in method of producing the crude borates has been its removal from the realm of industrial chemistry to the field of mining. With the development of extensive deposits of borate-minerals interstratified in thick sequences of Tertiary clays and sands, their winning becomes a strictly mining-enterprise, of the same kind and of the same certainty as the digging of coal or iron-ore. The major supply of the world's production of commercial borax now comes from the United States. While formerly all of the boric salts of commerce were laboriously extracted from the waters of saline lakes of the arid regions, or from the bottom-salts of desiccated ponds, it later was largely slowly leached from ancient desert shales and clays. During these periods the borax industry was a very hazardous and expensive vocation.

Oct 1, 1909

Coal Division Industrial Minerals Division Minerals Beneficiation Division Mining, Geology and Geophysics Division Established as a Society February 26, 1957 OFFICERS AND COMMITTEES J W Woomer, President A B Cummins, President-elect S D Michaelson, Past President C E Lawall, Eastern Regional Vice-President D W Scott, Central Regional Vice-President 3 D Forrester, Western Regional Vice-President R B Ladoo, Treasurer John Cameron Fox, Secretary

Jan 1, 1959

By Frederik W. de Klerk

INTRODUCTION During the past 40 years, there has been in the United States of America and other industrialised Western countries a distinct displacement in the procurement of minerals from domestic sources towards an increased dependence on imported minerals. This was caused in part by one or each of the following: a lack of local supply of particular minerals, domestic source depletion or exhaustion and the relative ease and inexpensiveness of obtaining minerals from comparatively unexploited sources in underdeveloped and some developing countries, notably in the Middle East, South America, Southern Africa, and Australasia. Governments of the industrialised nations, concerned about the reliance of their economies on imported raw minerals examined both the degree of reliability and the extent of mineral resources in the countries and regions supplying the essential minerals. This brought a painful awareness of the vulnerability of industrialised countries as a result of the possible interruption of their mineral imports. In this regard, the United States of America may be quoted as a case in point: a report by a House of Representatives Subcommittee on Mines and Mining (Santini Subcommittee)1 revealed that the United States in 1980 was dependent on foreign sources for more than 50 per cent for 24 of the 32 minerals essential for national survival. The Subcommittee also acknowledged that although the United States may develop its own alternative energy sources, there are in many cases no substitutes for the strategic + minerals imported from foreign sources, from countries which are often unstable at best, hostile at worst. This resulted in various policy responses as well as contingency measures, amongst other, renewed emphasis on the utilisation of domestic mineral resources, an intensified search for substitutes of critical minerals and increased stockpiling programmes. Increased attention was devoted to analyses of the political and economic conditions prevailing in the regions from which strategic and other minerals are exported to the industrialised countries, and the formulation of policy measures vis-a-vis those regions. One region which attracted a considerable degree of attention has been Southern Africa, and in particular South Africa.2 The Santini Subcommittee affirmed that while the bulk of the minerals imported by the United States is supplied by a number of source countries, a host of critical[t] minerals vital to the well-being of that country (and this includes all the Western industrialised countries) originates from Southern Africa, a region, deservedly referred to as the "Persian Gulf of Minerals". Apart from the Republic of South Africa the mineral-rich countries concerned are Angola (diamonds, iron ore, oil), Botswana (diamonds, coal), South West Africa/Namibia (diamonds, uranium), Zambia (copper, cobalt), Zaire (industrial diamonds, copper, cobalt) and Zimbabwe (gold, nickel, chromium, asbestos). The Subcommittee however noted that, with the exception of cobalt, the greatest portion of the reserves of the critical minerals listed, lies within the borders of South Africa. SOUTH AFRICA A RELIABLE PURVEYOR OF MINERALS In view of the continual instability and political risk, along with the nationalisation of mineral industries in third world countries, importing industrialised nations have in recent years become more and more concerned about security of long-term supply, and have in consequence begun to diversify their mineral enquiries to areas where the following conditions prevail: • Long-standing record of consistency of supply; • An economic system of private enterprise; • Political stability; • A well integrated infrastructure, with a maintenance of transportation and development costs at realistic levels, and • Attractive investment opportunities, with security of the return of profits.

Jan 1, 1982

By George Holderer

THE Enos Coal Mining Co. owns an area underlaid by coal, of approximately 5000 acres. This property is situated 9 miles from Oakland City, in the southern part of Indiana. The mine has been in operation 5 years, during which time some 350 acres have been stripped, and stripping is now proceeding at the rate of about 100 acres per year. TOPOGRAPHY These coal lands consist of gently-rolling agricultural fields which in times past were farmed for wheat. There is no timber and but very little brush to contend with. The overburden varies from 10 to 60 ft. in depth. A thin bed of slate overlies the coal, followed by limestone, which varies from 3 to 15 ft.; this, in turn, is followed by sandstone, slate, shale and clay. There is a very wide variation in the thickness of all of these beds. The coal has an average thickness of 5 ft., and is a good grade of high-volatile bituminous. MINING OPERATIONS Briefly, the sequence of operations is: drilling holes with churn drills; blasting with L. 0. X.; stripping overburden to uncover coal and, finally taking up the coal, which is sent to a tipple for cleaning and sizing. In order to show what is being accomplished by the use of L. 0. X., results will be shown from May to November, 1926, inclusive, and compared to the same period in 1925. No work was done in No. 1 pit during May, 1925, hence all figures are unduly low for this month. Drilling There are in use 8 No. 44 Loomis clipper drills, caterpillar traction with gasoline engines; recently these were equipped with extra heavy stems, measuring 26 ft. overall and 4 ½ in. dia., to increase the speed of drilling. In addition, 4 No. 1 ½ G non-traction drills have been acquired, and are used to save the time of the larger drills when recleaning is necessary.

Jan 1, 1927

US 4,133,866-Selective recovery of the bound sodium content of red mud obtained in the production of alumina by the Bayer process The red mud is mixed with aqueous ferric sulfate, the resulting suspension stirred intensively at a temperature of 15-85°C and adjusted to a pH value of from 4.4 to 4 6, and the solids are removed. The clarified solution of sodium sulfate can be used directly for the leaching of additional bauxite T Lakatos, M Miskei, J Szolnoki, F. Toth, and L Revesz, assigned to Aluminiumipan Tervezo es Kutato Intezet, Almasfuzitoi Timfoldgyar, and MTA Geokemiai Kutatolaboratorium. Jan. 9, 1979. 3 pp (423-208). Filed: 10¬28-77 (846,588) Priority: Hungary, 10-29-76 (AU 364). US 4,145,398-Continuous digestion of bauxite with aqueous sodium hydroxide, with higher throughput in existing plants or the construction of smaller plants with equivalent capacity The ore suspension at a solids concentration of 1-6% by weight and temperature of 200-300°C is flowed through a digestion tube or nest of tubes at a velocity of preferably from 2 to 5 m/s and under a pressure of from 10 to 200 atm Heat is supplied by a fluid heat carrier flowing in countercurrent in a concentric outer tube. Preferably, some of the red mud is recycled to the digestion operation. L. Plass, assigned to Vereinigte Aluminium-Werke A.G Mar 20, 1979. 5 pp. (423-121) Filed: 2-27-76 (754,749) Same: British 1,437,548, dated May 26, 1976 Same Canadian 1,008,253, dated Apr 12, 1977. US 4,146,573-An aqueous slurry of red mud, formed in the Bayer process production of alumina from bauxite, can be solidified by treating the red mud with a described quaternary ammonium salt, continuing mixing until the red mud has set up to a rigid mass, and recovering the solidified concentrated red mud J Kane, assigned to Nalco Chemical Co Mar 27, 1979 4 pp (423-82). Filed 8-2-78 (930,251).

Jan 1, 1980

By J. C. Bradley

The relation of annealing temperature to conductivity of copper wire has been determined. Conductivity hard was 98.26 per cent. After a 10-min. heat,ing at 200" C. it was 98.69. By annealing 10 min. at 300" C. a large increase, to 100.93, occurred. Maximum conductivity, 101.15, was attained after a 500" C. anneal; thereafter it decreased to 100.53 after a 950" C. anneal. If copper is gassed the decrease is much more than this. Material and Method The work was done on high grade electrolytic copper, 99.942 per cent, copper plus silver, silver 0.0008 per cent. It was hot-rolled to 1/4 in., then cold drawn to 0.080 in. The wire was cut into 25 5-ft. lengths and numbered 1 to 25 as cut. Four samples were tested hard. The others were wound into 5-in. diameter coils. For the 100" C. heating a coil was put into water, the water brought to . boiling, and the wire kept at this temperature for 10 min. For the higher temperatures the coils were placed in envelopes of sheet copper, a little water added, and the envelopes sealed by folding over the edges twice, and hammering them together. This kept the air out very well. The envelope and wire were brought to the desired temperature; this was maintained for 10 min., then the whole was water-quenched. Results Data from the tests are shown in the table and plot (see Fig. 1); conductivity is referred to the International Annealed Copper Standard at 20" C. Conductivity hard is considerably less than conductivity soft.1 The increase is sharp when the wire anneals. The maximum, 101.15 per cent, in the particular material used, comes at 500º C.; thereafter the conductivity falls to 100.53 per cent. after 950" C. annealing, a drop of 0.62 per cent.

Jan 1, 1927

By William Campbell

(Cleveland Meeting, October, 1912.) THE structure of iron and steel, though the object of so much study and research for the past 25 years, is by no means thoroughly understood. In the first place, we have three or more distinct iron-carbon thermal diagrams, each with its own supporters, and each representing a theory of the structure and constitution of cast-iron. In the second place, by reason of the fact that austenite, the solid solution of carbon in iron, decomposes in the solid state into ferrite, or pure iron, and cementite (Fe3C), and that quenching from above this transition-range, no matter how rapid, cannot entirely prevent the change and thus preserve the austenite by itself at ordinary temperatures, it happens that under the microscope we find, in addition to the ferrite, Fe3C, and austenite, which the thermal diagram of steel requires, it series of transition-products with distinctive structures, to which have ,been given the names martensite, troostite, sorbite, etc. Now these transition-products, in addition to the solid solution, austenite, have been the source of much controversy, at times very bitter. One side would insist that, say, troostite was an entity, which the other side would deny, pointing out that it must be a transition-mixture, with a particular structure. That austenite was a solid solution of carbon in iron has been denied by one school ; we have been told that Fe24C dissolved both Fe3C and Fe, and thus gave rise to a whole series of quenching-products-all this in spite of the fact that no matter how the thermal diagrams differ in regard to cast-iron, they all agree in regard to the solid solution, austenite, for Fe24C finds no place on the diagram. Thus it happens that while the authorities fight both in regard to the iron-carbon diagram and the structures met with in hard- * Associate Professor of Metallurgy, Columbia University in the City of New York.

Dec 1, 1912

By M. L. Samuels

DURING the period from 1910 to 1920, there was a lively interest in the subject of grain growth and many papers were published, followed by interesting discussions. Questions dealing with the fundamentals of grain growth-why and how it occurs-were treated in papers by Howe,1 Jeffries,2 Sauveur,3 Chappell,4 Beilby,5 Mathewson and Phillips,6 McAdam,7 Carpenter and Elam,8 Stead and Carpenter,9 Ruder,10 as well as others. Since that decade, much indeed has been done regarding the practical control of grain size, and it is now possible to order material having a size specified in the American Society for Testing Materials classification. Also, one hears the term "spliced boundaries" used in connection with certain tungsten lamp filaments" wherein it is important to prevent "sagging" between consecutive turns of the helix." This practical use of a certain knowledge as to the things that influence or even control grain growth should not be taken as an indication that the subject has been thoroughly explored and that nothing more can be learned from fundamental studies. It is with this thought in mind that a report of some observations and experiments on abnormal grain growth is believed justified. Abnormal grain growth is met with in heat-treating high-carbon steels in the austenitic range,13 in the hardening treatments of high-speed steels, 14.11 and in the low-temperature annealing of strained low-carbon steels as in sheet and wire material. Entirely aside from these instances of exaggerated grain growth, which some might consider as freakish, it is thought that abnormal growth is simply a case where the growth forces and the forces tending to prevent growth are almost, but not quite, evenly balanced. Information relative to grain-growth characteristics in general may be obtained from a study of abnormal growth conditions, which may be looked upon as vantage points. Reflection will show at once that if growth forces are great in comparison to inertia or resistance to growth, many crystals start to grow and, for that reason, none becomes very large, whereas if inertia is predominant no growth at all takes place. Under conditions in which

Jan 1, 1938

By J. A. Jr. Church

I. EARLY FURNACES. COPPER blast-furnace construction in America has long recognized a general standard in the rectangular mater jacketed shaft with separate forehearth. The details, however, and especially those relating to shaft dimensions, have had to meet a great variety of conditions, and show no uniformity whatever. Selecting a few of the present day Western plants, we find furnace lengths varying from 12.5 to 87 ft., widths at tuyere level from 42 to 84 in., and heights above tuyeres from 5 ft. 4 in. to 22 ft. 4 in. ; and comparing present designs with those of the past, we meet contrasts no less striking. Unlike its transverse section, the length of a furnace has come to depend rather on the size of unit desired than on the requirements of smelting ; and if the question of length be ignored, several of the various existing designs can be grouped together on the basis of a common transverse section. This section, having a width at tuyere level of 56 in. and a height above tuyeres of 18 ft., was developed at Great Falls, and the story of its development contains some interesting features. Ground was broken for the Great Falls works in the spring of 1891. About a year later, the concentrator was able to begin operation, followed within the next few mouths by the Brueckner, reverberatory, and converter departments, and in April, 1893, by the first blast fur-

Jan 7, 1913

By D. S. Jacobus

It is proposed to give in this paper an estimate of the cost at which carburetted and uncarburetted water-gas will have to he sold, in order to compete successfully for steam-boiler use with anthracite coal. The following are analyses of the gas direct from the generator, and of the same after it has been carburetted for illuminating pnrposes. Per cent. by Volumes. I. 11. Uncarburetted. Carburetted. Nitrogen,.4.69 2.5 Carbonic acid,.3.47 .3 Ethylene,....... 0 12.5 Oxygen,....... 0 .2 Benzole vapor,...... 0 1.5 Carbonic oxide,.36.80 29.0 Marsh-gas,.2.16 24.0 Hydrogen,.52.88 30.0 100.00 100.0

Jan 1, 1889

By Walter E. Heinrichs

The following is a condensed version of an open letter addressed to Bil Gilbert of Sports Illustrated: Your article, "When a Law Fights a Law, Sports Illustrated. April 26, 1971, betrays considerable unfamiliarity with the subjects of ecology, social science, mining law and history. In a magazine as widely circulated as Sports Illustrated, an article of such a slanted nature misleads the general public.

Jan 1, 1971

By C. G. Palagi, S. S. Stillar

The C. E. Weed concentrator treats 51,000 tons per day of 0.5% to 0.7% copper ore received from the Berkeley Pit, the Continental East Pit and the Butte underground mines. Improved operating techniques and conversion from semi-autogenous secondary grinding to ball milling have increased tonnage from an original design of 42,000 tpd. Separate treatment of sands and slimes, with recovery of soluble copper from the slimes, has increased total copper recovery. Concentrator tailings are pumped 600 vertical feet and 20,000 horizontal feet for disposal.

Jan 1, 1976

By T. E. Eagan, W. R. McCrackin

IN dealing with segregation in babbitt, and its effect on the final cast structure, which is a bearing, it is obviously impossible to cover all of the compositions manufactured. Each composition, of course, will exhibit certain specific types of segregation. However, as examples,, two compositions of babbitt are presented: one a tin-base of well-known analysis and the other a lead-base, which in the past few years has found wide usage. Bearings usually are cast either statically or centrifugally; therefore the effect of these two methods on segregation is presented. EXPERIMENTAL PROCEDURE A slab of babbitt 1/2 in. thick by 5 in. wide and 17 in. long was cast, using a book mold with the long edge vertical. An A.S.T.M. grade 2 babbitt was used (3.5 per cent copper, 7.5 per cent antimony, remainder tin), to which 0.10 per cent tellurium had been added. Unfortunately, no metal without tellurium was available. The mold to hold the babbitt was heated to approximately 300°F., the temperature being judged by the babbitter. The pouring temperature of the babbitt was 875°F. (470°C.). One slab was made by allowing the babbitt to cool without stirring. The other slab was stirred during the entire cooling cycle. This stirring consisted of a vigorous churning or puddling into the mold until complete solidification had taken place. Three samples were removed from these slabs. One was taken at the extreme bottom, another half way to the top, and another at the extreme top, all at the center of the width. Chemical, macroscopic and microscopic examination was made of all samples. Table I shows the chemical analyses obtained at the described positions [ ] in the slab. The analyses show no serious amount of gravity segregation. Microscopic examination from edge to edge of the slab showed little change in structure. From top to bottom there was a progressive coarsening of the grain size in the stirred slab but little change in the slab that was not stirred (Fig. I). No definite exhibit of segregation could be detected. In line with our experimental study on the tin-base babbitts, we cast an almost duplicate slab using A.S.T.M. Alloy No. 15, containing 0.9 to 1.25 per cent tin, 14.75 to 15.5. per cent antimony, 0.80 to 1.25 per cent arsenic and 0.4 per cent copper. The slab was 16 in. long and 3/8 in. thick, cast with the long side vertical. One slab was allowed to cool normally and the other was stirred continually during cooling. The pouring temperature of the babbitt was

Jan 1, 1944

By V. H. Gottschalk

THE solubility of gases in metals has been of interest since Graham's time in 1866, but, although the subject was actively studied by iron and steel metallurgists during the eighties, the era of painstaking laboratory investigation begins in 1907 with the publication of Sieverts'1 thesis on the occlusion and diffusion of gases in metals. Since then, Sieverts has worked almost continuously in this field, and his views on the subject are the prevailing ones at the present time.2 Probably the most important result obtained by Sieverts, and frequently verified since by other observers, is the discovery that at a constant temperature the solubility of almost all gases in both the liquid and solid state of most of the metals is proportional to the square root of the pressure (for pressure above 100 mm.). The obvious explanation of this fact is that the gas dissolves as atoms and not as molecules, although it has been pointed out a number of times, first by Donnan and Shawl in connection with their work on the solubility of oxygen in silver at 1075° C., that the formation and solution of a compound of the metal and gas would also be indicated by a variation of the solubility with the square or higher root of the pressure. Sieverts4 himself raised the question whether the usual explanation (i. e., that the gas dissolves as atoms) may not be wrong, when he found that the square root law held also for the solubility of sulfur dioxide in molten copper; in which case dissociation into simpler molecules or atoms does not take place. Stubbs5 subsequently showed that Sieverts and Krumbhaar's "constant" for sulfur

Jan 1, 1932

By R. S. Dean

THE first attempt to establish an equilibrium diagram of the lead-antimony series was made by Roland-Gosselin1 in 1896. This investigation classified the system as a purely eutectiferous one, with the eutectic at 12.5 per cent. antimony and 228° C. In the next year, Stead2 placed the eutectic temperature at 247° C. The error in temperature made by Roland-Gosselin, however, has been perpetuated in the literature with a remarkable degree of persistency; this value was accepted by Campbell (1902), and Ewen (1910),3 and will be found in the last edition of Desch's3 Metallography (1922). Gonterman's investigation, made in 1907, was the most complete one available at the time the present investigation was started. He concluded' that the system was a simple eutectiferous one and placed the eutectic at 13 per cent. antimony and 247°C. Other investigations by Tammann (1907),5 Garbow (1909),6 Rudolfi (1910),7 Loebe (1911),8 and Leroux (1913)9 added little, if any-thing, to Gonterman's diagram. A number of investigations have been made of physical properties of the alloys. The electrical conductivity of the series was studied by Matthiessen (1860)10 and by A. W. Smith (1921);" the thermoforce by Rudolfi (1910),12 and Pelabon (1923);13 the specific heat by Durrer

Jan 2, 1926

By J. R. Cahoon, H. W. Paxton

The possibility of using unidirectionally solidified, two-phase alloys as an approximation to fiber composite materials is investigated. The short-term me.chanical properties and failure modes of unidirectionully solidified A1 (rich)-Cu alloys containing ap -Proximately 0, 17.5, and 27.7 vol pct of 0 phase 'fibers" are determined at temperatures from 25" to 500" and compared with those obtained for conventionul SAP alloys. In a previous publication,' hereafter referred to as I, the possibility of understanding some of the room-temperature mechanical properties of unidirectionally solidified castings was explored. For Al(rich)-Cu and Al(rich)-Mg two-phase alloys over a substantial range of compositions, the yield and ultimate strengths and common ductility measures were very adequately predicted from the principles of fiber strengthening4 and the analysis of ductility outlined by Gurland and Plateau." The results obtained in I suggest the possibility of using unidirectionally solidified, two-phase alloys to simulate fiber composite materials where the inter-dendritic second phase or constituent acts as the reinforcing material. Recent attempts concerning the fabrication of fiber conlposites have concentrated on producing composites with a good bond between fiber and matrix and with very long fibers so that their maximum contribution to the strength of the composite may be realized. However, these objectives are difficult to attain in practice and present fabrication processes are either extremely laborious or costly.13 The slow, unidirectional solidification of eutectics has received considerable attention as a method for producing composite materials. 5,6 This method can fulfill both of the above objectives but it is currently laborious, expensive, and has the additional disadvantage that the volume fraction of reinforcing phase cannot be easily varied. On the other hand, unidirectionally solidified, two-phase alloys, also with a good bond between the phases, are relatively easy to make and the volume fraction of reinforcing "fibers" can be easily varied by changing the average composition of the alloy. The disadvantage of the cast alloys is that the mechanical effectiveness of the "elongated interdendritic reinforcements" (EIR)* may be reduced due to their rela- tively short lengths, the w factor in Eq. [2] of I. However, if the EIR have a high strength their contribution can be considerable. For composite materials containing discontinuous cylindrical fibers of various lengths the ultimate strength is given by1 where it is assumed that the composite fractures when the fibers fail. In Eq. [I], a, is the stress in the matrix just prior to failure of the composite, Vf is the total volume fraction of fiber reinforcing constituent, Vf(l+) is the volume fraction of fibers whose lengths exceed the critical length, I,, which is defined as the shortest length of fiber in which the stress can build up sufficiently to break the fiber. af is the fracture strength of the fiber material, w is a factor accounting for the discontinuity of those fibers whose lengths exceed I,, 1-/d is the average aspect ratio of those fibers whose lengths are shorter than I,, and t is the shear stress in the matrix at the fiber-matrix interface. The factor w is dependent on the length of the fibers and also on whether deformation of the matrix occurs plastically or elastically. However, for a given length of fiber, w is smaller when elastic deformation of the matrix is assumed.' It is of interest to consider the properties of simple unidirectionally solidified, two-phase alloys at elevated temperatures in view of the possibility of using suitable modifications for high temperature service. Knowledge of the creep behavior of these materials is still rudimentary (although under active investigation) and the present paper concerns itself with short time tensile properties of some alloys similar to those investigated in I (i.e., unidirectionally solidified Al(rich)-Cu alloys). Unidirectionally solidified alloys containing 5.6, 17, and 23 wt pct Cu were tested parallel to the direction of solidification at temperatures from 25" to 500°C. In the present investigation, the alloys were homogenized for 2 days at 535°C giving a matrix of homogeneous a phase (5.2 wt pct Cu) and an interdendritic constituent (EIR) which was completely Q phase (53 wt pct Cu). EXPERIMENTAL Alloys of nominal composition 5.6, 17, and 23 wt pct Cu (containing approximately 0, 17.5, and 27.7 vol pct 8 phase, respectively, after homogenization at 535°C) were prepared by melting 1200 g of A1 (99.99 pct) in a high purity graphite crucible and adding the appropriate amount of freshly cleaned copper chips (99.9 pct). The molten alloy (at 700°C) was poured into a preheated graphite mold (also at 700°C) and the ingot unidirectionally solidified by impinging water on the steel baseplate of the mold. The alloy was degassed immediately

Jan 1, 1970