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Members whose deaths were reported from Apr 7, 1923, to Apr 5, 1924 Elected Died 1918 ADKINSON, HENRY M 1923 1900 AGNEW, WILLIAM C 1923 1894 ASHLEY, H H 1923 1897 AUSTIN, KENNETH 1924 1903 AYERS, EMMA L C 1923 1913 BAECHTOLD, CHARLES A 1924 1900 BAIN, HUGH A 1924 1919 BASHORE, E GORGAS 1923 1920 BATTELLE, GORDON 1923 1923 BAYLES, GERARD L 1924 1881 BROCK, CHARLES 1923 1903 BROOKE, HENRY 1923 1876 BROWN, HARVEY H 1923 1904 BROWN, THOMAS E 1923 1919 BUCK, DANIEL M 1924 1906 CHALMERS, THOMAS S 1924 1881 CLEMES, JOHN H 1923 1896 COLLINS, HENRY F 1924 1871 COURTIS, WILLIAM M 1923 1915 CRESSON, B F, JR 1923 1921 CROWE, WALDO P 1923 1920 DARNELL, J ORA 1923 1911 DAVIS, HENRY G 1924 1918 DAVIS, ROBERT S 1923 1916 DEANE, WILLARD A 1924 1901 DEMPSTER, WILLIAM 1924 1911 DEVEREUX, W B, JR 1923 1895 DICKENSON, F M 1924 1904 DRUM, FRANK G 1924 1875 DUDLEY, P H 1924 1916 EATON, ARTHUR 1923 1919 EATON,SHERMAN 1924 1911 GRIFFITH, WILLIAM 1924 1919 HILSDALE, PAUL 1923 1922 HODGES, I F 1923 1916 HOFIUS, MAX, T 1924 1914 HUGHES, HOWARD R 1924 1919 HUMMEL, CARL B 1923 1874 HUNT, ROBERT W 1923 1921 JONES, ERNEST EVANS 1923 1917 JOSLIN, CHARLES T 1923 1918 KASJENS, JACOB G 1923 1899 KIRKEGAARD, PETER 1924 1920 KLAUS, HARRY C 1923 1892 KNOERTZER, HENRI1924

Jan 1, 1923

By H. W. Schadler

The superplastic behavior of low carbon and manganese bearing steels has been evaluated. The results of elevated-temperature stress-strain rate and elongation tests are reported which indicate that high strain rate sensitivity (>0.5) and adequate elongations are achievable in ultrafine-grained steels 1 to 2 p, but at strain rates which are not commercially attractive. It has been demonstrated that the fine grain size is retained after long times and high strains if the temperature is kept within the range of the two-phase (a + ?) field. INTEREST in superplasticity has been stimulated by the desire to: 1) understand the origin of, and mechanisms responsible for, the large uniform elongations observed, and 2) exploit this property for commercial advantage in metal forming operations. Although the Zn-22 wt pct Al alloy presently being studied as a model material1-5 may find application in sheet forming and extrusion, the potential of super-plasticity should best be realized in large tonnage materials, such as steel and aluminum alloys. The degree of superplasticity in low-carbon and manganese-bearing steels has been evaluated. The results of elevated-temperature stress-strain rate and elongation tests on ultrafine grain size material are reported. Avery and Backofen6 and Hart7 have shown that geometrically stable flow leading to extensive uniform elongation in the tension test is associated with high values of the strain rate sensitivity, m, defined: Lozinsky had reported that titanium and zirconium experience permanent deformation if subjected to a constant load and cyclic heating through the temperature range of the phase transformation. Although strain rate sensitivities in excess of about 0.2 had not been reported previously for steel, permanent deformation had been observed11-13 in a wide variety of steels subjected to a constant load and cyclic heating through the temperature range of the a-? phase transformation. Thus by analogy, steel could be expected to exhibit high strain rate sensitivity but only in the a + ? condition. High strain rate sensitivity has been observed at 650°C (a + Fe3C), but not reported as such, by Bailey, Dickenson, and pearson14 in 1931 at a strain rate of about 10-9 per min. It then remained to determine whether high tensile elongations would be observed in a rate-controlled test at constant temperature and at what strain rate strain rate sensitivity values greater than 0.5 would be observed. Since previous experience8 had indicated the importance of fine grain size to realizing high m at reasonable strain rates, it was first necessary to produce an ultrafine grain size and then keep the grains from growing during the test. The results of this investigation show that fine grain size can be readily produced16 and maintained by restricting the temperature of testing to below the ? transus. Further, superplasticity (high m and large uniform elongation) is observed. However, the strain rate range is only marginally useful for commercial forming operations with the finest grain size produced. MATERIAL The material investigated initially was a 1.9 wt pct Mn, 0.42 wt pct C, hot-rolled bar previously used by Low and Turka1015 and available in the laboratory. The 0.500-in. round was cold-rolled to a 0.090-in. flat, annealed for 4 hr at 850°C in argon, air-cooled, and cold-finished to 0.050 in. Subsequently, four additional steels of the compositions given in Table I were investigated to explore the effects of manganese, carbon, and test temperature on the observed stress-strain rate behavior. These steels were melted under argon, cast to 0.75 by 2 by 5 in. slabs, hot-rolled at 850°C, surface-finished to 0.13 in., and cold-finished to 0.050 in. Sheet tensile specimens 0.200 in. x thickness with 1- or 2-in. gage length were cut parallel to the rolling direction. Table I also includes the nominal transformation temperatures for the AISI 1340 and the four experimental steels. EXPERIMENTAL PROCEDURE Production of Fine Grain Size. Ultrafine grain size (1 to 5 p) was considered essential for this studv. Grange16 has described two techniques for producing

Jan 1, 1969

By Joseph C. Mead, Alan Stanley

The MacIntyre Development of the National Lead Co. is located at Tahawus, N. Y. The operations involve the mining and concentrating of a titaniferous iron ore to produce an ilmenite concentrate and a magnetite concentrate. Construction of the MacIntyre plant was commenced during the summer of 1941,when world conditions threatened to cut off the supply of Indian ilmenite. An open pit mining operation was developed and the crushing and milling equipment put in operation in July 1942. A general description of the operation was given in the Adirondack Issue of Mining and Metallurgy for November 1943. The metallurgy of the mill operation was described by Mr. Frank R. Milliken,* Plant Manager, National Lead Company, MacIntyre Development, and presented at the AIME New York Meeting, February 1948. The magnetite concentrate produced in the milling operation was too fine (minus 20 mesh) to be used directly in iron blast furnace operation, and most of the magnetite had to be stockpiled in 1942 and 1943. In 1943, the Defense Plant Corp. built a Greenawalt sintering plant at Tahawus, N. Y., to put the magnetite concentrate in a more suitable form for use in the iron blast furnace. The Greenawalt sintering plant consists of three 10 by 25 ft sintering pans designed to produce 1800 gross tons of sinter per 24 hr. The vacuum to each pan is produced by two Greenawalt fans in series, pulling approximately 30,000 cu ft of air per minute at 50 in. water gauge vacuum. The plant started operation in August 1944. The present plant production averages 25 tons per operating pan hour (approximately 224 lb per operating hour per square foot of grate area) of plus 1 in. sinter. Raw feed to the plant consists of 61 pct magnetite, 4 pct anthracite coal culm, and 35 pct minus 1 in. return fines which are conveyed to a pug mill where the materials are mixed thoroughly and water added to give the mixture 5.5 to 6 pct moisture. The mixed prepared feed is conveyed to two 4 by 10 ft vibrating screens where the minus 1 in. plus 5/8 in. return fines are screened out and discharged into a surge bin for use as a hearth layer. The minus 5/8 in. prepared feed is discharged into another surge bin for use as prepared feed. A charge car, electrically operated, having a capacity of one charge of prepared feed and several charges of hearth layer, lays a thin layer of plus 5/8 in. return fines and 9½ in. depth of prepared feed into the pans. A fluffing roll and a vibrator on the car fluffs and spreads the prepared feed into the pans. An ignition car, electrically operated, ignites the top of the bed with a 30 sec flash burn. The 9½ in. bed sin-ters in approximately 13 min. Dumping the pan, and recharging and igniting the bed requires 2 min. To improve the quality of the ilmenite concentrate produced in the mill and to reduce the amount of titanium dioxide lost in the mill tailings and in the magnetite product, extensive research work and pilot plant operations have been done on grinding the crude ore to minus 65 mesh size (rather than to minus 20 mesh) and concentrating it by a combination of magnetic separation (for magnetite recovery) and flotation (for ilmenite re-covery). These tests have proved successful in increasing ilmenite re-covery and grade. With the development of the ilmenite flotation process to a stage where a full scale flotation plant was in the design stage, the problem arose of handling the 65 mesh magnetite concentrate that would be produced. In order to study and solve the problems of handling and sintering the 65 mesh magnetite in the sinter plant, a pilot sinter plant was secured from John E. Greenawalt. The effect of using 65 mesh magnetite in the sintering operations was then studied on the 2.4 sq ft test pan, operating under conditions as similar to the large plant as could be set up in the laboratory. A series of tests were run in the test pan on present sinter plant feed that had been mixed in the plant pug mill. An average production and an average quality of sinter produced in this series

Jan 1, 1950

COUNCIL OF SECTION DELEGATES F J Meek, Chairman H A White, Vice-Chairman H R Gault, Secretary Division of Earth Sciences National Research Council 2101 Constitution Avenue Washington 25, D C

Jan 1, 1954

By Robert F. Mehl

EXTENSION of physical and chemical methods of research in the study of metallic behavior continues rapidly, particularly in the correlation of behavior with crystal structure, and in the analysis of elastic and plastic properties. The growth of the science of metals during 1933 calls for special comment; the need for special reviews and for textbooks and monographs is now acute, as might he supposed from the number of references appended to this article, a list which is much abbreviated.

Jan 1, 1934

By H. C. Jennison

Two distinct types of defects occur at times in copper wire as a result of the use of dies of improper design or undesirable wire-drawing practice. The conditions under which these defects may be produced, as well as precautions to be taken in order to prevent them, have been known to The American Brass Co. for many years. The quality of the copper wire bars and rods has too often and unjustly been held responsible for these particular defects and it is to correct any such belief that this paper is presented. An extremely high quality of electrolytic copper has been supplied to the trade by all refineries for the last 20 years at least. The purity of the copper would average well above 99.900 per cent. The casting of the wire bars has been handled in a generally satisfactory manner. The bars have been cast sound, with a flat to slightly crowning set and have been free from sloppy edges, cold sets, etc. In other words, the wire bars have met A. S. T. M. specifications and have been generally satisfactory. For the most part, they have been everything that could be desired from a quality standpoint yet most of the wire mills in this country and in Europe have at times held the quality of the copper responsible for the two types of defects described in this paper. As a matter of fact, these defects are produced entirely in the wire mills. The author has visited many of the large wire mills in the United States and in Europe to investigate these defects. In some cases the trouble has been so serious that the wire mill has ceased operations. At times the wire mills are reluctant to believe that they are responsible for the defective product. The effect of die design, wire-drawing practice, etc., upon the quality of copper wire has received little study on the part of wire mills, particularly those that have commenced operations in the last few years. Two Types of Defects One type of defect is generally known in this country as "check marks;" in Europe it is termed "crowfeet" (Fig. 1). This defect occurs in the surface of the copper wire, in the form of V's, which are always

Jan 1, 1930

By THOMAS J. CLIFFORD

IN 1926, finer grinding began to be a feature of the milling practice of the Southeast Missouri lead district. Nothing since the adoption of flotation has caused greater changes and greater improvement in results. The trend toward finer grinding, with the consequent discarding of tailing at finer sizes, and consequent lower assays in lead, continued to progress until 1931, when the abnormally low price of lead brought a halt: that is, the better metallurgical results obtained would not offset the increased costs due to higher power and necessary maintenance. Since 1931 a slight tendency toward the discard of coarser tailing has taken place. , In 1926, larger rod mills i.12 ft. 1 in. by 6 ft. 6 in.) than any previously used in the district were installed in cue plant, and a new primary crushing plant, of greater capacity was built. This combination demonstrated immediately the better metallurgical results obtainable by finer grinding and all the mills now running have adopted the practice.

Jan 1, 1934

By Robert C. Freas, William H. Lane, David J. Krohn

Maysville, Kentucky, is the location of Dravo Lime company's new 9 070 mt(10,000 tons) per day limestone mine and 2 727 mt (3000 tons) per day calcination plant. This complex has been designed as a unit, and capitalizes on recent technological advances. Geologically the Dravo facility is.located on the eastern flank of the Cincinnati Arch, with the high calcium limestone being found at a depth of approximately 274 m (900 ft). A systems approach has been employed in designing and equipping the mine. This allows for maximum production while maintaining flexibility and versatility. All hydraulic drilling, large LHD equipment, and an extendable mine conveyor system are utilized in a five-part mining cycle. A modular concept modifies the room and pillar system to optimize ventilation. The limestone is calcined in three 5.18 x 61.87 m (17 x 203 ft) KVS rotary kilns with a design capacity of 909 mt (1000 tons) per day of lime per kiln. The kilns are coal fired and equipped with preheaters. Lime storage is provided by three 57 m (186 ft) high concrete silos with a combined capacity of 40 909 mt.

Jan 1, 1976

By Dilip K. Paul, Charles H. Jacoby

The economic importance of salt domes has been recognized throughout the world, primarily because of oil and gas accumulations on their flanks, and to a lesser degree, for the value of their salt and potash. Recently they have become of value as hosts for cavities used to store hydrocarbons. In the near future we believe that their main value will be a source of geothermal energy. Although tremendous effort has been expended on the understanding of the geology and physical characteristics of the strata intruded by salt domes, relatively little energy has been exerted in the comprehension of the salt dome itself. Salt domes have long been recognized as a geological heat anomaly. With respect to other sedimentary rocks, salt is a good conductor of heat. Expressing values in 10-3cgs units, sedimentary rocks vary from 1.0 to 8.0; metamorphic rocks from 5.2 to 8.4 and igneous rocks from 3.1 to 9.8. Rock salt in its pure form has a thermal conductivity of 17. Thus a salt dome can be expected to act as a conduit bringing heat vertically from deep within the earth's crust.

Jan 5, 1974

Membership at the end of the year 1951 was 19,711 including 2228 Student Associates. The data in the third column include these Student Associates. 1. This includes all the cash dues income received from new and old members of all grades. 2. All cash initiation fees received. 3. Net income received from advertising in the three journals. The figure was $72,273, for MINING ENGINEERING; $39,844 for the JOURNAL OF METALS; and $31,564 for the JOURNAL OF PETROLEUM TECHNOLOGY. Income in 1950 was $54,572, $30,390, and $18,443 from these sources, respectively. 4. Receipts from individual sales, nonmember subscriptions, and multiple subscriptions of members. 5. Includes Transactions volumes and the Petroleum Statistics volume. 6. Sales of all other printed matter except special volumes sponsored by certain Funds. Includes a considerable sale of preprints and reprints of technical papers. 7. Does not include dividends and interest from certain Funds whose income reverts to those Funds. 8. Miscellaneous income not included in any of the above categories. 9. The total income compares with $493,197 -in 1950, an increase of $29000.

Jan 1, 1952

By Lawrence W. Teufel

A method to determine in situ stress directions and magnitudes from anelastic strain recovery measurements of oriented core has been used to determine the principal horizontal in situ stresses in the Rollins Sandstone in a deep well near Rifle, Colorado. The principal horizontal stress directions were determined directly from the principal horizontal strain recovery directions. The principal horizontal stress magnitudes were calculated from the principal strain recovery magnitudes, overburden stress, and Poison's ratio of the rock using a viscoelastic model. The accuracy of the in situ stress directions and magnitudes determined from anelastic strain recovery measurements was substantiated by a direct comparison with open-hole hydraulic fracture stress measurements. The anelastic strain recovery method predicted the magnitudes of the maximum and minimum horizontal principal stresses to be 54.5 MPa and 51.9 MPa, respectively; with an azimuth of N63ºW ± 8º for the maximum horizontal stress. The hydraulic fracture stress measurements yielded maximum and minimum horizontal principal stress magnitudes of 49.6 MPa and 46.8 MPa, respectively. The azimuth of the maximum horizontal stress ranged from N50ºW to N70°W.

Jan 1, 1984

I. THE ENERGY CRISIS STILL EXISTS A. ALTHOUGH IMMEDIATE SHORTAGE IS NOW ALLEVIATED BY: 1. Increased imports through lifting of Arabian embargo; a. Imports were 6.5 million bpd during the week ended January 17, or 1.3 million bpd higher than last year. b. 1.7 million bpd higher than March '74. 2. Decreased demand resulting from higher prices and conservation. a. January 1975 demand was 17.9 million bpd, 0.1 million bpd lower than January 1973 and … b. 2.0 million bpd, or 10% under originally projected demands for January 1975. c. Gasoline (excluding tax) went up 59% from 27d/gal in August 1973 to 43c/gal in September 1974. d. Gasoline demand for January 1975 was 6.3 million bpd, 0.1 million bpd higher than 1973 but 0.7 million bpd ( 10% ) under projected demand. 3. Increased crude and major product inventories. a. January 17, 1975 crude and major product inventory was 794 million bbl, 99 million bbl higher than the same date in 1973. b. 105 million bbl increase since April 12, compared to only 38 million bbl increase during the same period in 1973.

Jan 5, 1975

By R. H. Hopkins, R. W. Kraft

X-ray and metallographic analysis reveal that the preferred cryslallograPhic relationships in direc-tionally solid~fied Pb-Sn eutectic specimens can be stated: interface growth direction, Experiments in which tin single-crystal seeds were used to nucleate the eutectic demonstrate that the normal lamellar structure observed at steady state can be forced to break down initially to a semide-generate structure when the crystallograPhic direction of the tin seed does not lie within the preferred eutectic interface plane. A normal structure eventually develops by preferred grain growth. X-ray topo-graphs and rocking curves substantiate that the perfection of eutectic samples increases as growth proceeds until steady-state conditions prevail. RECENT years have seen substantial progress made in the understanding of eutectic solidification through both intensive theoretical1'' and experimental investigations (see Ref. 7 for a review and extensive bibliography of both aspects). Several important observations concerning the nucleation and growth aspects of binary eutectic solidification have been brought to light. Briefly some of these include the nonrecipro-cal nucleation of one phase upon another,'j9 the tendency for a specific low-index direction of one or both phases of the eutectic to be aligned in the growth direction during unidirectional solidification,'0711 and the production of lamellar microstructures having a preferred interface plane between "11-13 phases. Questions quite naturally arise as to the mechanism by which preferred grain growth evolves during eutectic solidification and what relationships (if any) connect the initial nucleation of one phase upon another with the preferred growth directions and interface planes observed after a few centimeters of growth in many systems. This study was initiated in an attempt to answer these questions. An experiment was devised in which both the nucleation and growth steps in the crystallization of a binary eutectic, Pb-Sn, could be correlated with subsequently developed eutectic morphology and crystallography. This was accomplished by nucleating the eutectic upon a tin single crystal seed and then causing the eutectic to grow from the seed by directional freezing. The morphology of the structures produced in this manner was then monitored metallographically and the orientation relationships and substructural perfection determined by X-ray analysis. The information thus ob- tained was correlated to the growth history of the samples. EXPERIMENTAL DETAILS The eutectic of composition 38.1 wt pct Pb and 61.9 wt pct sn14 was prepared by accurately weighing lead and tin of 99.999+ (from ASARCO and Lytess Metals and Chemicals, respectively), melting in a clean Pyrex beaker under an argon blanket, and casting into the proper crucible for resolidification as described below. Tin seeds were grown by the method of ~halmers," saw-cut, oriented by the Laue method, and soldered to the pull rod of the Czochralski puller. All seeds were given a final electropolishing (to assure the removal of any deformed material from the cutting operation) and acetone degreasing immediately prior to the nucleation experiment in which they were to be used. Eutectic samples were unidirectionally solidified in a horizontal graphite boat1' or by pulling from the melt16 with tin (or graphite) seeds. A flowing argon atmosphere was employed in all experiments and growth rates and temperature gradients, constant for a given run, varied from 2 to 4 cm per hr and 8" to 15°C per cm over the course of all the experi-

Jan 1, 1969

By C. A. Heiland

NOT only has the demonstration of progress in all fields of science been characteristic of the Chicago "Century of Progress," but the manner in which the fundamentals of these sciences have been displayed captivated the visitor's eye and ear at the same time. The average individual is interested most in progress which concerns his every-day life. He is fairly well educated in medicine, biology and certain aspects of physics. But how raw materials and chiefly minerals occur, how they are located, taken out of the ground and refined, is something which appears to be more remote from the every-day line of interest, and about which, therefore, the public knows comparatively little. This is particularly true of the oil industry, although it ranks in size second only to agriculture in the United States. In appreciation of the tremendous educational value which a complete exhibit on all phases of the mineral industries would have, both mining and metallurgical as well as oil inter¬ests took steps early to make these exhibits at Chicago a reality. The board of directors of the A. I. M. E. authorized an advisory committee to the Museum of Science and Industry early in 1932. It is divided into four subcommittees - for geology and petroleum, for metal mining, for coal mining, and for metallurgy respectively. The entire committee held its first meeting in Chicago on April 11 and 12, 1932, to advise with the Museum's officials and experts about the most advantageous arrangement of the minerals industries' and geology exhibits.

Jan 1, 1933

By F. W. Hillnhutter

In plant tests with a 9.7 m hearth diameter high top pressure blast furnace the influence of disintegration of sinter during low-temperature reduction on blast furnace performance was evaluated. The blast furnace burden during the test period consisted of 74% self-fluxing sinter with a basicity of CaO/Si02 = 1.3, 15% pellets, 6% lump ore, and 5% recirculated slags. The sinter for the test was produced in a modern sinter plant. By changing the fuel rate and/or the MgO content at a constant basicity CaO/Si02 sinters with different low-temperature disintegration properties could be produced. The blast furnace was equipped with pressure monitoring devices at medium height of the furnace stack wall. This device provided in addition to the normal operating data readings of pressure losses in the upper and lower part of the furnace. The basic physico-chemical factors determining low-temperature disintegration are explained. The testing devices and the extent of quality control measures of sinter during the test period are outlined. Conclusions are drawn from the plant test in relation to sinter properties.

Jan 1, 1977

By W Lindlief, Cyril Stanley Smith

Several investigators, mainly concerned with the mechanical properties of the alloys, have studied the so-called aluminum bronzes after various quenching and reheating treatments. Of these works, perhaps the most complete is that of Bouldoires, who studied changes of length, electrical conductivity, thermoelectric force, hardness and micro-structure on tempering quenched alloys containing 5 to 20 per cent of aluminum, although the work of Carpenter and Edwards,² Curry13 Greenwood,4 Braesco,5 Matsuda,67 Grard8 and others has added much to our knowledge of the changes occurring during tempering. The so-called acicular ß decomposes on tempering at temperatures between 350" C. and the eutectoid, giving rise to a Widmanstätten structure of a needles in a matrix of 6 or fine a + 6, associated with an increase in hardness and almost complete loss of ductility. Matsuda studied the eutectoid transformation by means of dilatation and electrical conductivity measurements during cooling at different rates. He found that on cooling at the rate of 10" C. per minute there was a decrease in electrical resistance and in length instead of the usual increase which occurred with slow rates of cooling. On tempering the rapidly cooled samples, the increase commenced at about 400" C. and at 520" C. the resistance and length had reached the equilibrium values. These peculiarities he accounted for as being due to a transitional phase ß' being formed, ß' having an electrical resistance and volume less than either ß or a + 6. Obinata9 published some electrical conductivity curves for copper-aluminum alloys showing a double break at the eutectoid temperature,

Jan 1, 1933

By N. P. Goss

ASTERISM appearing in X-ray Laue dia-grams is an extremely sensitive index of changes in the internal structures of indi-vidual 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.1-4 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 con-clusive, 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 be-tween mosaic and distorted grain struc-tures 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,7 has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-14 to 10-15 c.c., or 10-5 cm. in size.

Jan 1, 1940

By N. P. Goss

ASTERISM appearing in X-ray Laue dia-grams is an extremely sensitive index of changes in the internal structures of indi-vidual 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.1-4 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 con-clusive, 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 be-tween mosaic and distorted grain struc-tures 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,7 has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-14 to 10-15 c.c., or 10 5 cm. in size.

Jan 1, 1940

By Steven T. Mitchell

INTRODUCTION Mill production from the Homestake Mine in 1979 amounted to 1.29 Mt (1.43 million st) of ore containing 5.9 g/t of gold (0.172 oz per st) compared with 1978 production of 1.44 Mt (1.59 million st) containing 6.2 g/t of gold (0.180 oz per st). The average cost per ounce of gold produced in 1979 rose to approximately $250 contrasted with $176 in 1978. This increase in unit cost is the result of inflation, a diminishing ore grade, and productivity losses related to a shortage of experienced miners as well as compliance with federal regulatory requirements. Together, these factors prompted the investigation of several large-scale, highly mechanized underground mining methods. This analysis indicated Vertical Crater Retreat mining to be one of the safest underground methods known today, yet competitive with all other forms of stoping in terms of cost and productivity. Therefore, the feasibility of applying the VCR stoping method at the Homestake Mine was explored. Vertical Crater Retreat stoping is a recent innovation in large- scale underground mining based on C. W. Livingston's crater blasting theories. Figure 1 illustrates the method which consists of drilling 165.1-mm-diameter (6.5-in.) holes from a topsill down-dip to an under- cut on the level below. The bottom of each hole is then loaded from above with a predetermined charge weight and horizontal slices up to 4.27 m (14 ft) in thickness are blasted into the undercut. Broken ore is extracted from drawpoints located on or below the undercut level.

Jan 1, 1983

By E. C. W. Perryman

On electropolishing, high-purity Cu-Sn and Cu-Sn-P alloys with more than 5 to 9 pct Sn were found to contain many grain boundaries with a ridge-and-furrow profile. The effect was not eliminated by solution treatment and was present at the new boundaries in recrystallized material. It could be produced by diffusing tin into the 3 pct Sn alloy and it is concluded that the effect is due to enrichment of certain boundaries in tin, or possibly in an impurity present in the tin, in solid solution. IN the hot working of tin bronzes, especially those with moderately high tin contents, considerable difficulty is frequently encountered from intercrystal-line weakness, which results in cracking at the edges in sheet on strip rolling and in the unsupported regions of the rod in rod rolling.' These difficulties are not at all pronounced with up to 3 pct Sn, but at 5 pct Sn impose serious limitations and at higher tin contents, especially if the phosphorus content is also high, they may become very severe. In some work carried out at the laboratories of The British Non-Ferrous Metals Research Association it was found that a notable lack of ductility in tension at elevated temperatures, associated with intercrystal-line failure, was characteristic of tin bronzes even of relatively high purity. That the intercrystalline fracture is not due to a brittle or molten impurity phase at the grain boundaries was shown by the fact that the temperature at which intercrystalline fracture first occurred decreased with decrease of rate of straining. Tensile tests on some commercial tin bronzes, reported by Goetzel,² show a similar fall in ductility with increasing temperature. As no visual evidence had been obtained showing that the grain boundaries of the tin bronzes were different from those in copper, a more detailed microscopical examination was carried out, and the results of this are given in the present report. Several workers"' have observed that electrolytic polishing is a powerful tool for detecting small amounts of a second phase and in particular for detecting high solute concentrations, "equilibrium segregation," at grain boundaries. Since it had been found that the suggested solutions for electropolishing bronze and the standard solutions for brass and copper did not give satisfactory results it was first necessary to find a suitable electropolishing solution.' Experimental Procedure Materials Used: The cast and wrought materials used for this work were the same as those used for the mechanical tests referred to above. They comprised 3, 6, and 9 pct Sn alloys without phosphorus and the same three basic alloys with 0.03 and 0.4 pct P. A 5 pct Sn alloy without phosphorus, of similar purity, was also examined. The basis materials were Chempur tin, high purity 15 pct phosphor-copper and cathode copper, and spectrographic analyses are given in Table I. Treatment: The cathode copper was first melted under charcoal, degassed by plunging marble chips beneath the surface, and cast through a coal gas flame into sand molds to produce a number of small ingots which after machining were of a suitable size for subsequent vacuum melting. Chill cast bars of the alloys, approximately 1¼ in. in diameter, were then made by melting and casting in vacuo, the tern-

Jan 1, 1954