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By M. R. Stauffer, Z. Hajnal

Seismic velocity determinations over Precambrian outcrops near Flin Flon, Manitoba, indicate that several different rock types have sufficient velocity contrast to make reflection mapping possible. Stratigraphic and fault contacts between metasedimentary and metavolcanic rocks have been mapped at some depth. A mu1ti-fold reflection survey attempted to trace the depth extension of an ore-bearing (Pb-Zn) rhyolite horizon within the metavolcanic rocks. A synthetic seismogram has been produced from a 10,000-ft sonic log and provides means of comparing seismic records with the local geology. From this the optimum frequency spectrum and the maximum resolution of the seismic signals were estimated.

Jan 1, 1978

More than 400 members and guests registered for the 146th General Meeting of the Institute held in Mexico City Nov. 9 to 15, inclusive. Of these, 250 came by special train or automobile from 24 states of the Union, and the others were resident in Mexico. Mexican Government officials, headed by Manuel Santillan, Sub- secretary of the Department of National Economy, acting in. behalf of the President of the Republic, and including the Secretary of Foreign Relations and the Governor of the Federal District, were most hospitable in their official welcome and provided splendid entertainment of various kinds. A reception was tendered by Hon. Josephus Daniels at the U. S. Embassy. Among other hosts were officials of a number of large operating companies, including M. H. Kuryla, of the Real del Monte company; Jules Lacaud, of the CompaiLia Minera de Chontalpan; and Harry Wright, of the Consolidated Steel company.

Jan 1, 1937

By H. Kenworthy, M. M. Fine

The progress made to date in the mineral dressing of complex Arkansas titanium ores is reported in this paper. Concentrates of rutile, a dioxide of titanium, were produced by treating a submarginal ore from the Magnet Cove Rutile Co., Inc., Magnet, Ark. The rutile recovery at present is 45 to 50 pct of the total TiO2 with the possibility of increased recovery with additional research. The work reported herein is part of a general study which will later include results of investigation of other titanium ore bodies in the Magnet, Ark., area. The fragile character of the rutile minerals, the softness of the gangue, the occurrence of pyrite and leucoxene, and the considerable proportion of extremely small size rutile in the presence of montmorillonite- and illite- type clays in the Magnet Cove open-pit mine are the important factors in the mineral dressing of this submarginal rutile ore.

Jan 1, 1949

By David S. Butts

The high cost of energy has made many solution mining corporations turn from fuel consuming evaporators to solar energy and solar ponds. The generally held concept of a solar pond is an area enclosed by dikes into which brine is pumped, water evaporated by the sun, and the resulting salts scraped from the bottom of the pond. This paper will show that solar ponding is not simple. It is a science involving six main areas. These areas are (1) land conditions, (2) meteorology, (3) fresh water, (4) accessibility, (5) manpower and (6) mineral resources. Each area is discussed to identify important parameters that must be investigated before the viability of a solar pond complex can be established as a mineral recovery step.

Jan 1, 1985

By Harry C. Gatos, Frank J. Bachner, Mario D. Banus

The portion of the Nb-Sn phase diagram between 75 and 79 at. pct Nb at temperatures near the liquidus has been investigated by melting alloys of known composition and examining the microstmc-tzlres resulting when these melts were quenched. The Nb-Sn samples were contained in magnesia sleeves, and were mounted in a high-pressure apparatus. It was shown that Nb3Sn me1ts by a peri-tectic decomposition and that the composition of the compound Nb3Sn at the peritectic horizontal lies between 77 and 78 at. pct Nb. Analysis of the phases present in the samples was accomplished by anodic staining techniques and an electron-microbeam analyzer. DURING the past several years a great deal of work has been devoted to the Nb-Sn system, and the bulk of this work has been primarily concerned with the intermetallic phase Nb3Sn. However, the melting characteristics of Nb3Sn have not been investigated because of the difficulty in maintaining known compositions due to tin losses by vaporization, and the added difficulty of containing Nb-Sn alloys without sample-container reaction at the high temperatures involved. This paper reports on the development of a technique for containing Nb-Sn alloys under pressure high enough to prevent tin losses at temperatures in excess of the liquidus. Using this technique, melts of known composition were made and a phase diagram near the liquidus is proposed based on the microstructures resulting when these melts were quenched. EXPERIMENTAL The Nb-Sn alloys weighing 0.7 g each were prepared in the form of cylinders. Niobium powder, -200, +325 mesh, and tin shavings with a minute amount of tin powder for a binder were mixed in the desired proportions and cold-pressed at 50,000 psi in a 0.150-in. die. This cylinder was then enclosed as shown in Fig. 1, and the entire arrangement mounted in a 2.6-in. pyrophyllite tetrahedron.' The desired temperatures (-2500°C) presented several problems in high-pressure container materials. Boron nitride, the usual sample holder, was found to react with niobium to form the nitride. However, MgO cans and plugs machined from refractory rods did not melt nor react with the sample. Thick tantalum contact disks were used to carry the large currents (~450 amps) to the graphite heater, since tantalum did not melt and had enough strength to prevent extrusion of the sample. It was further observed that the graphite heater and tantalum disks could not be in direct contact with the pyrophyllite because it melts and decomposes at these temperatures to kyanite and coesite (SiO2),2 the former reacting with graphite and the latter with tantalum to form the silicide. The use of a MgO outer sleeve

Jan 1, 1965

By Henry Emmett Gross

Two types of decline curves are considered and their applications are discussed. The first is the well-known semilogarithmic decline curve having the rate of production plotted on the logarithmic scale and the time on the horizontal scale. The other curve is the percentage of oil in the fluid versus cumulative production, and it is plotted on Cartesian coordinate paper. These curves are illustrated by carefully and adequately labeled graphs. Where conditions permit application of both types of curves for rationally determining the reserves of a well, both should be applied and the most conservative reserve should be chosen. Formulas are given for determining the economic limits. For a semi-l~~arithmic~decline curve the formula is: A = B X C X D X E X F or B = A/C ? D X E X F A = total monthly operating cost (average of past year), B = economic limit in barrels of oil per day, C = days in an average month = 30.4, D = market price of crude per barrel, E = 1-royalty, F = 1-gross production tax, G = water production in barrels per day at the economic limit, H =per cent oil in fluid at economic limit. The economic limit for a per cent oil in the fluid curve is: H = B/B+G X 100 The semilogarithmic decline curve is treated first. Straight-line extrapolations on semilogarithmic paper follow the compound interest compound discount law, hence the ensuing formulas derived from this law may be used in computing reserves for such extrapolations: [1___1/(1+Y)]

Jan 1, 1939

By Henry Emmett Gross

Two types of decline curves are considered and their applications are discussed. The first is the well-known semilogarithmic decline curve having the rate of production plotted on the logarithmic scale and the time on the horizontal scale. The other curve is the percentage of oil in the fluid versus cumulative production, and it is plotted on Cartesian coordinate paper. These curves are illustrated by carefully and adequately labeled graphs. Where conditions permit application of both types of curves for rationally determining the reserves of a well, both should be applied and the most conservative reserve should be chosen. Formulas are given for determining the economic limits. For a semi-l~~arithmic~decline curve the formula is: A = B X C X D X E X F or B = A/C ? D X E X F A = total monthly operating cost (average of past year), B = economic limit in barrels of oil per day, C = days in an average month = 30.4, D = market price of crude per barrel, E = 1-royalty, F = 1-gross production tax, G = water production in barrels per day at the economic limit, H =per cent oil in fluid at economic limit. The economic limit for a per cent oil in the fluid curve is: H = B/B+G X 100 The semilogarithmic decline curve is treated first. Straight-line extrapolations on semilogarithmic paper follow the compound interest compound discount law, hence the ensuing formulas derived from this law may be used in computing reserves for such extrapolations: [1___1/(1+Y)]

Jan 1, 1939

not weaken. I saw him shortly before he was killed; his conduct under fire was splendid and an inspiration to his men. His loss is felt deeply by all ranks. Thanks to him and to others, who like him, paid the full measure of devotion to their country, our line was held until the critical situation in that vicinity was at an end. He died the true death of a soldier, with his face to the enemy. As we now look back, it is easy to believe that this holding of the line of defense intact by General Carey and his men was a determining factor in the outcome of the war. To have played so important and noble a part in this vital effort as that taken by Perry is assuredly the privilege of few. Our lives, it seems, are like capital entrusted to us to be expended as wisely and effectively as we may. With them we purchase whatever of accomplishment the stuff that is in us permits. It is impossible to escape profound regret that a career so full of the highest promise, and a personality so overflowing with all that is fine and lovable, should have been cut short at the age of thirty-one. Yet who can doubt that in a few months Perry bought with his life the fullest achievement of a life-time—a glorious part in the salvation of Liberty and Justice and Decency, indeed of Civilization itself! L. C. Graton.

Jan 1, 1920

By E. S. Machlin

RECENTLY, there has been much activity in the field of nucleation of martensitic transformations.'- One of the problems in this field is the calculation of the rate of nucleation (number of plates nucleated per unit untransformed volume per unit time) in terms of observable parameters. Two such observable parameters are the fraction of the length of a straight line which corresponds to the portion of the total length of the line that lies in the martensitic phase and the number of plates intersected by this straight line per unit length of line. Because of the necessity of a valid answer to this problem, the following investigation was undertaken. Although this problem has been treated in the past, a derivation of the relation between the volume and linear fractions of martensite will be described to illustrate the method used in the succeeding analyses. It is assumed that the martensitic plates are in the form of a right circular cylinder having a small height relative to the radius of the base. The volume fraction of martensite is then: fr = lXNl,hjAl [1] where f, is the volume fraction of martensite, and Nij is the number of plates per unit total volume having the area Ai and the height hi. The linear fraction of martensite is obtained as follows. For the plates having the particular area A, and height h,, the fraction sin 0 dB* will have their cylinder axes between the angles 0 and 0 + d0 to the straight line along which the linear fraction of mar-

Jan 1, 1953

By E. V. Howard

During the recent expansion of precipitate copper production at the Chino Mines Division of Kennecott Copper Corp., Santa Rita, N. Mex., local studies of the dump leaching process were intensified. As these studies progressed, it became apparent that a reliable method for locating leach solutions within the dump was required, since the contact between the leach solutions and the copper-bearing ma.teria1 determines recovery. In the past, the problem of determining leach solution contact has been attacked by various methods, including destructive testing (dump dissection), indirect observation (such as chloride or dye tracers) and mathematical or laboratory model studies, but they have not proved completely satisfactory. The investigation of methods for in situ observation of leach solutions led to consideration of radiation logging in drillholes, which are subsurface techniques used in petroleum exploration and development for locating fluids and measuring porosity. A significant advantage of radiation logging is that, unlike other types of logging, measurements may be made in cased holes, since gamma rays and neutrons will penetrate steel and cement. Three techniques are currently used at Chino: Natural gamma ray logging; neutron-neutron, or moisture logging; and gamma-gamma, or bulk density logging.

Jan 4, 1968

By P. Martignan

UNTIL quite recently, Alsace was the only district in France where petroleum could be found in somewhat industrial quantities. The Pechelbronn fields produce, however, only about 80,000 tons a year, which represent approximately one-eighth of the domestic consumption. Much research work has been done in Alsace to find the prolongation of the Pechelbronn fields, but instead of oil the drillings revealed the existence of large deposits of potash. This can, be easily explained when one remembers that the Pechelbronn oil is of the Oligocene period, and, that in the Alsatian stratification the Oligocene lies immediately on the Keuper, i. e., on the strata that originate from a period during which the largest salt and potash deposits were constituted. Before the war, and mostly at the end of the last century, some wells were drilled in various districts of France where some analogies could be found with the Alsatian geology, the borings being mainly made in the Triassic and Tertiary beds. They led to negative results. After the war, the growing importance of oil urged the necessity of resuming the explorations. But it is our belief. that this was greatly facilitated by the enacting of new legislation, which is embodied in the Mine Act of May 16, 1922.

Jan 3, 1925

By R. L. Templin, D. A. Paul

The modulus of elasticity is defined as the ratio of stress within the proportional limit to corresponding strain. This property, as thus defined, is a constant for each kind of material; and in tension or compression is usually designated by the symbol E. The modulus of elasticity serves as an index of the stiffness of a material or a measure of its ability to resist change of shape under stresses not higher than the proportional limit. In view of the frequency with which the modulus of elasticity is used in engineering calculations, it is surprising to note the uncertainty that exists as to authentic values, and the marked lack of published information relating to the variation of the constant E within individual alloy systems. A value of 10,000,000 Ib. per sq. in. has been quoted as representative of aluminum and its alloys. This value has been found to be approximately corrcct for pure aluminum and aluminum alloys in which the total percentage of the alloying elements is low, but seriously in error in the case of alloys that contain relatively large amounts of the alloying elements. a National Metals Handbook. b Intcrnatiunal Critical Tables. '' Aluminum Co. of America. " Based on density of alurminum (2.70). c Smithsonian Pliysical Tables.

Jan 1, 1931

By E. Rudy, St. Windisch

The only complete phase diagram investigation of the Ti-W system is by Maykuth and coworkers,&apos; Fig. 1. Although previous work by Gonser2 indicated complete miscibility, later investigations3°5 essentially confirmed the diagram depicted in Fig. 1. The present study was undertaken because preliminary results on metal-rich ternary Ti-W-C alloys indicated complete solid solubility between 0 titanium and tungsten at temperatures above 1300°C—in contradiction to the presently accepted diagram. The powdered elements, as well as crystal bar titanium and tungsten sheet, were used in the preparation of the experimental alloys. The iodide titanium, obtained from Foote Mineral Co., Exton, Pa., had a total impurity content of less than 410 ppm, of which 150 ppm were interstitials (H, O, N, C). The overall purity of the titanium powder (Var-Lac-Oid Chemical Co., New York) was better than 99.7 pct. Major contaminants, in ppm, included: 0, 800; N, 10; H, 1500; Fe + Co + Ni + Cu + Zn, 50; C1, 200. The measured lattice parameters of the titanium were a = 2.94A and c = 4.68,A. The tungsten sheet and the tungsten powder (Wah Chang Corp., Albany, Ore.) contained the following impurities (in ppm, values in parentheses refer to the sheet tungsten): Mo, 50 (70); 0, 140 (110); Fe, 20 (60); Ni, 20 (not determined); N, 110 (not determined); sum of other impurities, <60 (<100). Samples from the iodide titanium bar stock and from tungsten sheet were prepared by repeated melting of the chipped materials in a nonconsumable electrode arc furnace under high-purity helium. The melted alloys were heavily cored, and homogeneity of the alloys could only be achieved after prolonged heat treatments at subsolidus temperatures. The majority of the alloys were therefore prepared by cold compacting the well-mixed powders in steel dies and pre-homogenizing the compacts for 6 hr at 1300°C in a tungsten-element furnace. The vacuum was better than 10"6 Torr, but for additional protection the sample container was wrapped in zirconium foil. Both preparation methods led to identical results. The measurements of the solidus temperatures were carried oat in the Pirani-type furnace described in a previous paper.6 Incipient melting in alloys containing between 20 and 90 at. pct W was rather difficult to detect visually, and therefore a photoelectric transducer system7 was employed to indicate the phase change. For the investigation of the solid-state equilibria, the specimens were first homogenized for 2 hr at slightly subsolidus temperatures in the Pirani fur- nace and then reequilibrated at, and rapidly cooled (-100°C per sec) from, the selected equilibrium temperatures. After the runs, the alloys were analyzed microscopically and by X-ray diffraction. With the exception of spot checks for oxygen and nitrogen in processed alloys, no other chemical analyses were performed. However, as the weight changes of the alloys during processing were within 0.05 pct and the lattice parameters of indeqendently prepared alloy series agreed within 0.0015A, it is reasonable to assume that no significant concentration shifts with respect to the nominal compositions had occurred. The measured solidus temperatures, shown together with literature data in Fig. 2, ascend smoothly from

Jan 1, 1969

By F. Weinberg

The distribution of solute during the progressive solidification of dilute Sn-Ag alloys was determined in both solid and liquid as a jbnction of growth rate, rod diameter, temperature gradient, and solute concentration, using radioactive tracer techniques. The results indicated that partial mixing occurs in the liquid during freezing for most of the conditions investigated, approaching complete mixing for larger rod diameters (>2mm) and slow growth rates. Measured solute distributions were fitted to distribution functions based on diffusion controlled solute transport in the liquid state, by treating the normal solute diffusion constant and distribution coefficient as variable solute transport and segregation parameters. Values of these parameters were determined for the growth conditions investigated. Observations were made to determine whether mixing in the liquid was primarily due to volume changes in freezing or to differences in density between solute and solvent. The former effect was investigated using a selected Sn-Bi alloy as a solvent with zero volume change on fusion, and the density effect was studied using vertical solidifications of Sn-In and Sn-Ag alloys, systems having, respectively, very small and large differences in density between solute and solvent. The result indicate that mixing in the liquid cannot be primarily attributed to either volume changes or density differences. THE solute distribution in progressively solidified rods of dilute alloys, in which there is complete mixing in the liquid, is given by the expression1 where C, is the solute concentration in the solid at the point where the fraction g of the material has solidified, C, is the initial solute concentration and k is the equilibrium distribution coefficient. If it is assumed that there is no significant con-vective mixing in the liquid, then the solute distribution in the initial portion of a semi-infinite rod has been calculated to be2 where t is the time from the start of freezing and x1 is the distance in the liquid ahead of the solid-liquid interface at time t. Expressions [1] and [2] describe the limiting cases of solute distribution in the liquid, i.e., complete mixing, or no convective mixing; in practice it might be expected that the solute distribution would be somewhere between these two cases. pfann3 has suggested that Eq. [I] is applicable for partial mixing, as well as complete mixing, if an effective distribution coefficient k1 is used instead satisfactorily describes solute distributions in rods of magnesium, n-g, and b-sb6 alloys that were progressively solidified from the melt without mechanical mixing. The values of kl were observed to depend on the growth rate4-6 and the temperature gradient.6 The purpose of the present investigation was to measure solute distributions in both the solidified rods and the melt as a function of the solidification variables, and to determine to what extent the observed solute distributions could be described by the above theoretical expressions, keeping in mind that expressions [2] and [3] have been derived solely for the case of diffusion controlled solute transport in the liquid and are not theoretically applicable to

Jan 1, 1963

By J. T. McGrath, G. B. Craig

Tensile tests on aluminum single crystals, grown from the melt, revealed that the yield stress of these crystals was raised as the amount of striation substructure was increased. The number of striation-type boundaries was varied by changing the rate of growth of the crystals. The results are interpreted in terns of a blockage of dislocation movement by striation boundaries. IMPERFECTIONS are known to have a large effect on the mechanical properties of metals. Teghtsoonian and Chalmers 1 studied a block or striation-type substructure in tin and found that the formation of the striations depended upon rate of crystal growth and orientation. They found that the angular misorienta-tion between neighboring striations varied between 15 min and 5 deg. Atwater and chalmers2 investigated striations in tin and lead, and found that purity was another factor which influenced their formation. There was a limiting purity above which the striations were straight and regular. There is little information in the literature concerning how substructures in melt-grown crystals affect strength. washburn3 introduced small-angle boundaries into zinc by a shear process and found a subsequent increase in yield stress which he attributed to the presence of these boundaries. Lauriente and pond4 found the critical resolved shear stress in aluminium crystals grown from the melt, to increase with etch pit density. The etch pits were used as an indication of growth imperfections. In Hibbard&apos;s5 work on lineage structure in copper crystals grown from the melt, he tested one crystal containing interlineage boundaries, and found a 50 pct increase in the critical resolved shear stress. Fleischer and Chalmers6, in a recent paper, mention briefly that, in the production of aluminium crystals from the melt when the growth rate was raised from 1.2 to 18 cm per hr, the yield stress increased 50 pct. They felt that the increase in yield stress with rate of growth might be attributed to a higher concentration of impurities in the gage length and also might be affected by the increased number of small-angle boundaries (striations). The present investigation was undertaken to determine the effect of the striation substructure on the strength of aluminum single crystals. EXPERIMENTAL PROCEDURE Aluminum single crystals of 99.9992 purity were grown from the melt using a technique described by Chalmers.7 The growth rate was varied from 0.6 to 20 mm per min, thus producing crystals with varying numbers of striation boundaries. To avoid prior deformation, the crystals were chemically cut to the desired length with a saturated solution of cupric chloride. They were then annealed at 580°C for 24 hr and allowed to cool slowly in the furnace. Finally, the specimens were electropolished using an electrolyte of 5 parts ethyl alcohol and 1 part perchloric acid. Each specimen was approximately 5 in. in length and 0.125 sq in. in cross section. The average orientations of the 5 series of crystals studied are shown on the stereographic projection of Fig. 1. The crystals were strained approximately 2 pct in a soft tensile machine. The strain sensitivity was 3.6 x 10-4 cm over a 5-cm gage length.

Jan 1, 1960

By Paul M. Tyler

MILITARY power stems from industrial power and industrial power in turn depends predominantly upon an ample and assured supply of mineral raw materials. It thus becomes the duty of mineral economists to collate the vast array of data and logical deductions in order to reach an unemotional judgment as to the ability of the Soviet economy to withstand the strain of prolonged military action on the modern scale. Russian publications, reports: and official speeches have been laboriously screened and analyzed. Since these are the sources of information for the lower echelons of the Soviet industrial organization itself, they carry factual data that can be pieced together to show the present-day pattern. Apparent contradictions and obvious distortions or omissions can often be rationalized on the basis of observations made by foreign engineers and consultants during the 1930&apos;5 and by checking against the technical literature published before even so-called technical articles were riddled by bombastic and presumptuous claims.

Jan 6, 1951

By A. C. Fieldner

THE COMMITTEE on Correlation of Research held two meetings in 1931. The first was a luncheon meeting on Feb. 19, at the Engineers Club, New York, attended by eight members and four guests-William H. Bassett, past-president of the Institute; Robert E. Tally, president; H. Foster Bain, secretary; and Alfred D. Flinn, director of the Engineering Foundation. Mr. Bassett gave a short resume of the circumstances leading to the formation of the Committee and expressed his opinion that the objectives as expressed by the Committee in its first annual report were in accordance with the ideas of the Institute officials. Mr. Tally stressed the great importance of research in the mining and metallurgical industries and stated that lie believed the Institute should encourage and promote research, and that this Committee could do a great deal to foster such work in the Institute. Mr. Bain pointed out that this Committee was appointed with a view to correlating and fostering research work. in the field of the Institute&apos;s activities. This could be done in various ways, as by encouraging the divisions and committees of the Institute to hold group meetings on research, by forming research subcommittees in the Institute divisions, and by bringing together research interest in. certain projects and the fund or organization that is equipped to carry out the project.

Jan 1, 1932

By L. W. Bahney

FREQUENTLY in using a thermo-electric pyrometer for measuring the temperature of a furnace, a hole is drilled at the back or side of the furnace, through which is introduced the tube containing the thermo-couple. At times the couple is left almost where it drops, for the reason that it soon becomes too hot to be handled easily, and the space at the back or side of the furnace may be so small and uncomfortably hot that an easy and accurate adjustment is nearly impossible. In order to overcome this clumsy and unscientific method of using the thermo-electric pyrometer, I designed an adjustable stand, to hold the clay or quartz tube unclosing the platinum and plati-num-rhodium leads that constitute the couple of the Le Chatelier thermo-electric pyrometer. This stand also allows an easy and rapid adjustment of position to varying heights and angles, as may be desired for special reading. This stand is illustrated in Fig. 1. The couple in the tube might be of better service if the tube were held a little higher above the charge in a roasting-dish, changing the height and angle if desired. The stand, made of 1.5-in, water-pipe and mounted on casters, is heavy enough so it cannot be tipped over easily. It is adjusted to any position, and has a universal clamp which holds the clay or quartz protecting-tube. To avoid disturbing the wires of the couple at the cold junction each time the tube is moved, the cooling-bottle sets in a wire basket so placed that it moves forward or back with the couple. To overcome the necessity of leveling and adjusting a galvanometer at each furnace, a switch-board is used to connect

Jan 1, 1910

By M. Ahlers, Horace Pops

Slip features and formation of stress-induced mm-tensite have been studied in single crystals of fl phase Cu-Zn alloys in the composition range between 43 and 48 at. pct Zn. A phenomenological analysis is presented in which the glide planes and directions that me associated with the inhomogeneous shear in the martensite phase are predicted from the experimentally determined habit planes and macroscopic shear directions. It is shozun that the resolved shew component of the applied stress on the secondary shew system is a very important factor governing the formation of stress-induced martensite. A comparison is made between martensitic phases that form spontaneously upon cooling and those phases that arise from deformation. THE ß phase in Cu-Zn alloys is unstable and may transform spontaneously by a martensitic transformation1-3 during cooling. Thermoelastic and burst-type spontaneous martensitic phases have been observed3 in the composition range between 38 and 42 at. pct Zn. Martensite forms in alloys containing more than 42 at. pct Zn only by cold work below a temperature denoted as Md.4 Thus, alloys near the equiatomic composition can undergo a stress-induced transformation upon cold work at room temperature. Although data have been obtained concerning the effect of temperature5 and composition4 on the deformation of polycrystalline Cu-Zn alloys, it is rather surprising that few detailed studies6-8 on 6 brass have been conducted for single crystals where the stresses acting on crystallographic planes can be determined. A thorough understanding of transformation mechanisms requires knowledge of the role of stress and plastic strain. With this objective in mind we have made an investigation of the stress-induced rnartensite transformation in single crystals of 0 brass in the composition range between 43 and 48 at. pct Zn. Particular emphasis is given to the morphology and crystallographic features and a comparison is made between stress-induced and spontaneous martensite. I) EXPERIMENTAL PROCEDURE Master alloys having nominal zinc contents of 43, 45, and 48 at. pct were prepared from spectroscop-ically pure metals (>99.999 pct) in sealed quartz tubes under a partial pressure of helium. These alloys were cut into several pieces and converted into small rods by melting in quartz tubes. Subsequently, single crystals were grown from the rods by the Bridgman technique and homogenized for 3 hr at 820°C. Lattice parameter measurements were made from stress- relieved filings. Compositions, as determined from the reported variation of lattice parameter with atomic percent zinc,&apos; indicated a zinc loss of less than approximately 0.25 at. pct. The single crystals were electroturned using a phosphoric acid electrolyte into tensile specimens each with a center section of 1 mm diam and 1 cm gage length. Cylindrical specimens approximately 3 mm in diam and 10 mm long and spark-machined rectangular blocks approximately 3 by 3 by 10 mm were prepared for compression studies. These blocks were stress-relieved and electropolished to eliminate any stresses introduced by spark machining. Crystal orientations were determined to an accuracy of ±2 deg primarily from back-reflection Laue photographs, and sometimes by the rotating single-crystal method. Figs. 1 to 3 show the location of the tension and compression axes within unit stereographic triangles. All specimens were deformed plastically at room temperature using an Instron machine, the crosshead speed being 0.02 or 0.05 cm per min. A hard steel hemisphere was placed at the upper end of the compression samples to achieve uniaxial loading. Trace normals of slip markings and habit planes of strain-induced martensite were determined to an accuracy of ±4 deg from the rectangular blocks by a two-surface analysis and from cylindrical specimens by measuring the angle between the tensile (or compression) axis and the tangent to the surface trace for different rotations about the deformation axis. Slip

Jan 1, 1969

NEW YORK SECTION J. E. JOHNSON, JR., Chairman EDGAR RICKARD, Vice Chairman D. M. LIDDELL, Secretary, 7 Wall St., New York, N. Y. C. A. BOHN, Treasurer JOHN V. N. DORR LEWIS W.. FRANCIS The following minute was unanimously passed at a meeting of the NEW YORK SECTION AMERICAN INSTITUTE OF MINING ENGINEERS held on the evening of June 6, 1917, two regular meetings having been adjourned by unanimous consent until this date out of respect to the memory of the late Chairman of the Section. Minute The death of our beloved fellow member DR. DAVID H. BROWNE one of the foremost metallurgists and one of the most brilliant and original thinkers in the profession of mining engineers, the chairman for the past two years of this section, has caused throughout a wide circle of

Jan 9, 1917