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By E. Teghtsoonian, E. M. Schulson

The tensile behavior of bcc ordered P' AuZn single crystals (CsCl structure) has been investigated under varying conditions of temperature, composition, and orientation. Between -0.2 and 0.4 T, multi-stage hardening occurs fm stoichiometric and nonstoichio-metric crystals oriented near the middle of the primary stereographic triangle. At higher and lower temperatures, parabolic type hardening occurs, followed by work - softening at the higher temperatwes. Deviations from stoichiometry give rise to increased flow stresses. Multi-stage hardening was observed for most orientations, except along the [loll-[lll] boundary and near the [001] corner of the stereo -graphic triangle, where parabolic type hardening occurs. Along two slip systems, (hk0)[001] and (, operate simultaneously while in the [001] comer, slip occurs mainly on the system. Electron microscopy of deformed crystals revealed bundles of edge dislocations forming walls approximately Perpendicular to the glide plane. In general the plasticity of 4' AuZn closely resembles the plasticity of bcc crystals. In recent years, considerable interest has arisen concerning the mechanical properties of the CsCl type intermetallic compounds Ag Mg,'- Fe co,' and Ni Al.'-' The compound P'AuZn is structurally similar. It has a low and congruent melting point of 725"~,'" remains ordered up to the melting point,16 and pos-esses a range of solid solubility from 47.5 to 52.0 at. pct Au at room temperature.15 The present paper reports the results of an investigation on the general tensile behavior of material in single crystal form. Some dislocation configurations characteristic of the deformed state are also reported. The results of a detailed study of the slip geometry in AuZn are presented in a separate paper.17 PROCEDURE Alloy preparation, crystal growing techniques, and the procedure followed in selecting specimens of minimum composition variation are reported elsewhere.17 Dumb-bell shaped tensile specimens were prepared by carefully machining single crystals in a jewellers' lathe to a gage length of 0.80 in. and diam of 0.090 in. Back-reflection Laue X-ray patterns and room temperature tensile tests revealed that machining damage could be eliminated by electrochemically polishing 0.005 in. from the machined surface followed by annealing at 300°C for 1 hr. Specimens were polished in fresh 5 pct KCN solution (40°C, 12 v). Experiments were performed by gripping specimens in a self-aligning pin-chuck and threaded collet system, then straining in a floor model Instron tensile machine. All tests were performed in duplicate. Experimental variables included temperature, composition, and orientation. Unless otherwise stated the strain rate was 2.5 x 10"3 per sec. Liquid testing environments included nitrogen (WOK), nitrogen cooled petroleum ether (133" to 293"K), and silicone oil (293" to 488°K). Resolved shear stress-shear strain curves were electronically computed from autographically recorded load-elongation curves. Stress and strain were resolved on the macroscopic noncrystallographic (hkO) [001] system operative under the specific test conditions of temperature, strain rate, and orientation reported earlier.17 RESULTS The temperature dependence of the work-hardening curves is shown in Fig. 1 for gold-rich crystals of 51.0 at. pct Au oriented near the center of the stereo-graphic triangle. Over the range of intermediate temperatures from -200" to 400°K, they are very similar to those classically observed for fcc metals (reviewed by Nabarro et al.).'' The beginning of deformation is characterized by a region of decreasing hardening rate, stage 0, which is followed by a region of low linear hardening, stage I, and then a region of higher linear hardening, stage 11. At the higher temperatures, stage 111 is observed, a region of decreasing hardening rate. Over the intermediate temperature range, the extent of stage 0 and of the slow transition between stages I and I1 decreases with increasing temperature. Total ductility is large, often greater than 300 pct shear. As the temperature is either increased or decreased, the extent of stage I is decreased, giving rise to parabolic type flow and reduced ductility. Similar temperature effects have been reported for bcc ~r~stals.~~-~~ Below -14O°K, hardening is terminated in brittle fracture while above -400°K. initial hardening is followed first by work-softening and then by chisel-edge type ductile fracture. Stoichiometric (50.0 at. pct Au) and Zn-rich (51.0 at. pct Zn) crystals were also tested from 77" to -500°K. The effect of composition on the flow behavior is illus-

Jan 1, 1970

By R. E. Ogilvie, A. R. Kaufmann, S. H. Gelles

The solid-solubility limits of iron in beryllium were determined between 850o and 1200oC by analysis of differential type multiphase diffusion couples, using an X-ray absorption technique. The maximum value of the solubility limit was found to be 0.92 ± 0.02 at. pct (5.46 wt pet) at the eutectic temperature 1225°C. The solubilities of nickel and beryllium were determined between 900°and 1200°C by the same technique and the maximum solubility was found to be 4.93 + 0.01 at. pct (25.2 wt pet) at the eutectoid temperature, 1065°C. A previously unreported high-temperature phase which decomposes eutectoidally at 1065 °C was found to exist in the beryllium-nickel system at a composition of approximately 8 at. pct Ni (36 wt pet) by diffision-couple analysis. The presence of this phase was confirmed by thermal analysis and metallo-graphic analysis of the structure resulting from the eutectoid decomposition. G. V. Raynor1 has treated the solid solubilities of some of the elements in beryllium on the basis of the "Hume-Rothery" rules2 which have been modified to include ionic size and ionic distortion effects. It was predicted that the solubility of iron and nickel in beryllium should be slightly less than that of copper. The lowering of the solubility, according to Raynor, is due to a more unfavorable relative valency effect and an ionic size effect. Kaufmann and corzine3 have compiled data on the solubilities of elements in beryllium and have discussed them in the light of the Raynor paper. These authors feel that, because the elements having the greatest solubility in beryllium systematically fall in the Group VIII and IB Columns of the periodic table, the electronic structure greatly influences the maximum solid solubility of elements in beryllium. The solubility of iron in beryllium was determined by Teitel and cohen4 as part of the study of the beryllium-iron phase diagram. The determination was carried out by X-ray and thermal analysis and according to the phase diagram presented, the maximum solubility of iron in beryllium is 0.41 at. pct (2.5 wt pct) at 1225oC. However, it is estimated that the uncertainty in the position of the a-beryllium primary solid-solution boundary is about 0.5 at. pct (3wtpct). Losana and Goria3 in studying the beryllium-nickel phase diagram, determined the solid solubility of nickel in beryllium by thermal analysis. They found the maximum solubility to be between 1.65 and 2.65 at. pct (10 to 15 wt pct) at 1240°C. This value decreased rapidly with decreasing temperature. In determining approximate ranges of solubilities for different elements in beryllium, Kaufmann, et al,8 reported a value of between 1.3 and 1.7 at. pct (7.9 to 10.1 wt pct) for the solubility of nickel in beryllium. The value was obtained by metallographic examination of quenched alloys and lattice-parameter measurements. However, the authors also noted a single-phase structure for a 1.7 at. pct Ni alloy (10 wt pct) on cooling from the liquid. This would indicate a higher solubility range than was reported. ~isch,' in his X-ray studies of beryllium-copper, beryllium-nickel, and beryllium-iron intermetallic compounds, reports the disappearance of a second phase (Ni,Be2) in the beryllium primary solid solution at approximately 4 at. pct (20 wt pct). THEORY The analysis of concentration gradients in diffusion couples has proven to be a useful tool in determining phase equilibria.8-14 In this particular study the diffusion couples were chosen to straddle the expected composition range of the phase boundary, then heat treated at a given temperature and the concentration gradient evaluated. The composition of the phase boundary for a given temperature appears at a point of discontinuity of the composition gradient. Examples of typical phase diagrams and the concentration gradients which should be found in such systems are shown in Fig. 1. In the present work, gradients of the form of Fig. l(c) were obtained in diffusion couples made of pure beryllium and two-phase alloys of beryllium with either iron or nickel. The composition at the point where the gradient becomes discontinuous, Cs, corresponds to the solubility limit of either iron or nickel in beryllium. The analysis of the concentration gradients was carried out by an X-ra absorption method developed and applied by Ogilvie and later used by Moll13 and Hilliard.l4 It depends on the fact that the absorption of X-rays by matter is determined by the concentration and type of the various atomic species present. The relationship for the intensity, I, of a monochro-

Jan 1, 1960

By Enrique Hauser

FIRE-DAMP is a mixture of methane with other inert gases or combustible gases. The inert gases in question are carbonic acid, water vapor, nitrogen, etc. The combustible gases are hydrogen, ethane, etc. The study of the properties of fire-damp, therefore, becomes a study of the properties of methane and the influence on its properties of the different gases we have mentioned. Characteristic Properties of Methane 1. Respirability.-Methane being a paraffin is characterized by its weak chemical affinities. From the physiological, point of view one could substitute it for nitrogen of the air at least momentarily, without experiencing any difficulty in breathing the mixture consisting of 21 per cent. 02 + 79 per cent. CH4. I .have tried this on myself, making the gas exhaled -from the lungs burn subsequently in a Bunsen burner.1 From the chemical point of view, this weak affinity permits the gas to be burned in certain circumstances with hydrogen and oxide of carbon in an oxygenated mixture, with the result that the last two gases achieve only a fractional combustion. This practice has been utilized with success in the methods of analysis which I have perfected and which I describe later in this paper. 2. Retardation of Flashing Point.-A characteristic property of methane is its retardation of flashing point, noted by Davy in 1816 and studied by Mallard and Le Chatelier in 1883.2 Taffanel and Le Floch have recently confirmed these results.3 Let us recall the nature of this retardation:

Jan 2, 1916

By R. A. Deju, R. B. Bhappu

The theory of electrophoresis is briefly outlined and an apparatus which may be used for electrophoretic studies is explained. The results obtained using this apparatus are in agreement with those obtained by other investigators. How to solve some of the complications which occur in the measurement of zero charge and zeta potential is explained. It is believed that the apparatus described in this paper will allow rapid measurements of zeta potential, zero point of charge, electrophoretic mobility and zeta coefficient. For many years the phenomenon of electrophoresis has been studied, and much work has been done in designing an apparatus for better measurements of mobility, zeta potential and zero charge of minerals. Up to the present, most electrophoresis experiments have involved cumbersome equipment and tedious microscopic observation. The modified cell proposed in this paper obviates these drawbacks by using a Rayoscope together with a special system of lenses and filters. It therefore allows a faster and more accurate measurement of zero charge and particle velocity. THEORY Most authors currently regard zeta potential as the potential difference in an otherwise uniform medium between a point some large distance from the surface of the mineral and a point on the plane of shear. Fuerstenau,1 Miaw,2 and Gaudin and sun3 have performed some calculations of zeta potential using Henry's equation.4 Their results show wide discrepancies, probably due to differences in the past histories of the minerals used. The authors have also noticed this difference on determining the zero point of charge of quartz as shown on Table I.

Jan 1, 1967

By Thomas T. Read

The fact that certain types of ore-deposits have attained their present condition through the action of descending surface waters was, perhaps, first clearly pointed out by Posepny.l The oxidizing effects of such waters were discussed by Pen-rose,2 and many papers dealing with this phase of the subject have subsequently appeared. That secondary enrichment of sulphide ores, however, might be produced by descending surface waters was not clearly understood until after the copper-bearing veins of the Butte district, Mont., had been carefully studied by the geologists of the U. S. Geological Survey, although De Launay3 had suggested that sulphides might be transported from point to point and re-deposited in the zone above the level of ground-water. As a result of the study of the Butte district, two papers by geologists engaged in the work appeared within a short interval. The first by Weed: dealing with the enrichment of veins by later metallic sulphides ; and the second by Emmons; treating of the secondary enrichment of ore-deposits in general. In the latter paper it was pointed out that a typical vein of sulphide ores which has been subjected to the action of descending surface-waters exhibits four zones,—an upper or surface-zone, in which the changes hare been mainly of removal, the products being typically oxides; a second zone of oxide enrichment, in which the less soluble metals brought from above have been precipitated as carbonates or oxides; a third zone of sulphide enrichment,

Jan 1, 1907

By Harold Cook

Discussion of the paper of HAROLD EARLE COOK, presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 375 to 400. ALBERT SAUVEUR, Cambridge, Mass.-I think we must all agree with Lieutenant-Commander Cook when he says that there is a great deal of room for improvement in the annealing of steel castings and that better results would be attained if the annealing were conducted in closer agreement with scientific requirements. Whether even a carefully annealed steel casting can ever be made the equal of a steel forging of good quality is still a debatable question. Nevertheless, we all realize that very greatly improved results can be attained by careful annealing. Lieutenant-Commander Cook refers to some requirements calling for annealing steel castings above the Ac1 point. He is undoubtedly right where he says that this should be the Ac3 point. Take, for example, a steel casting containing, say, 0.35 per cent. of carbon, having a very coarse structure made up of coarsely crystalline ferrite. If this is heated just above the Ac1 point the ferrite remains, of course, just as it was before, while the pearlite is converted into a solid solution, austenite. Upon cooling, all this austenite is again converted into pearlite, or sorbite, while the coarse structure of the ferrite remains unchanged and the annealing has accomplished very little. It is therefore surprising that the requirement of annealing above the Ac1 point should appear, in these specifications.

Jan 5, 1916

By D. O. Ehrenburg, R. J. Watson

During the earlier period of electrical prospecting, the search for orebodies was by far the most important application of this method of geophysical prospecting. In the past few years, however, increasing attention has been paid to the possibilities of this method in the investigation of subsurface structures. Not only have fault zones been located, but attempts have been made to determine the depth to certain strata and thus contouring on some bed which proves to be a good "electrical marker." Many workers have published the results of field tests showing how their particular interpretations have agreed with the actual field conditions, but very few have stated their method of interpretation. Weaver, Hummel and Stefanesco and Schlumbergerl have given a more theoretical discussion of the resistivity methods. Hummel and Stefan-esco and Schlumberger have published mathematical solutions for the flow of electricity in a medium involving four layers. In this paper the authors present a solution for the flow of electricity in a medium of any number of horizontal strata. By means of this solution, curves showing the relationship between the apparent resistivity and the electrode spacing can be computed for ideal cases. Point-source in an Infinite Homogeneous Medium In resistivity measurements the current is conveyed to the earth by means of two electrodes, which can be mathematically treated as point-sources of equal and opposite strength. A point-source of strength I is defined as a point at which electricity is being generated at the constant rate of I coulombs per second, or I

Jan 1, 1932

By W. J. West, T. D. Mueller, J. E. Warren

The authors have presented valuable information on the influence of the interfacial tension and the contact angle on the recovery efficiency of the waterdrive process. It is considered, however, that the following points deserve a closer examination. 1. As pointed out by Wyllie and Spangler1 the displacement pressure PD i.e. the pressure required to initiate the displacement of the wetting phase from the core, is a measure of the maximum pore diameter dmax. If the capillary pressure Pe as a function of the wetting

Jan 1, 1956

By Samuel S. Wyer

Bethlehem Meeting, February, 1906 THE following abbreviations have been used in the text:¬ Am. MF. and Iron World. American Manufacturer and Iron World, Pittsburg, Pa. Can. Min. Rev. Canadian Mining Review, Ottawa, Can. Cass. Mag. Cassier's Magazine, New York, N. Y. Col. Eng. Colliery Engineer, London, Eng. Col. Guard. Colliery Guardian, London, Eng. Eng. and Min. Jour. Engineering and Mining Journal, New York, N. Y. Eng. News. Engineering News, New York, N. Y. Engr. Engineering, London, Eng. J. I. and S. I. Journal of the Iron and Steel Institute, Lon¬don, Eng. Jour. W Soc. of Engrs. Journal Western Society of Engineers, Chicago, Ill. Lond. Eng. The Engineer, London, Eng. Mines and Min. Mines and Minerals, Scranton, Pa. North of Eng. I. M. E. North of England Institute of Mining Engineers, Newcastle-on-Tyne, England. Oester Zeitsch f. Berg u. Hüt. Oesterrcichische Zeitschrift für Berg. und Hüttenwescn, Vienna, Austria. Pract. Engr. Practical Engineer, London, Eng. Proc. I. C. E. Proceedings Institution of Civil Engineers, London, Eng. Trans. A. I. M. E. Transactions American Institute of Mining Engineers, New York, N. Y. Trans. A. S. M. E. Transactions American Society Mechanical Engineers, New York, N Y Trans. Fed. I. M E. Transactions Federated Institute Mining Engineers, Newcastle-on-Tyne, England. Trans. I M E Transactions Institute Mining Engineers, Newcastle-on-Tyne, England.

Mar 1, 1906

By James M. Townsend

INTRODUCTION The first stage in planning any mining venture is to determine whether the reserves are of sufficient quantity and quality to warrant commencement of mining activities. In addition to total reserve values a modern mining operation requires information on possible support problems, various pillar sizes, and an estimate on recoverable reserves. To achieve this goal in U. S. coal mines, up-to-date computer methods have been applied to existing ground control technology to provide the mining engineer with a reasonably accurate method of determining such figures. The purpose of this paper is to present a mine planning suite comprised of three computer programs, CONTUR, RESERV-COAL and RAMPLAN, created to accomplish this task. These programs were developed at VPI under the sponsorship of the Office of Coal Research (now Energy Research and Development Administration), and are currently available to the mining industry. A basic assumption in the construction of the CONTUR program is that a coal seam is variable in nature. The data available to the mining engineer comes from randomly spaced points, namely boreholes and sampling points, on outcrops or in adjacent mines. These randomly spaced data points are used in the CONTUR program to estimate numerical values at evenly spaced grid points and to provide approximate contour plans. Given the necessary gridded data, RESERV-COAL calculates raw and clean coal tonnages and then provides breakdown on the quantity of coal within specified ranges of ash, sulfur, BTU and reject. RAMPLAN (Rock Mechanics Applied to Mine Planning) also uses gridded data to calculate mining dimensions and estimate recoverable reserves, thereby

Jan 1, 1977

By Garth M. Crosby

Hugh E. McKinstry (Professor of Geology, Laboratory of Mining Geology, Harvard University, Cambridge, Mass.) Pre-Cambrian age for the Coeur d'Alene mineralization, as indicated by isotope studies and recently discussed by Silverman, Long, and Kulp' would explain some features of the mineralogy of the district that have long been a puzzle. In the Silver Belt, especially in the Sunshine mine, lead-zinc min erali zation passes downward into tetrahedrite ore. Although commercially speaking this is a rich silver zone, the silver is, quantitatively, a mere impurity amounting to a small fraction of 1 pct. In effect the zonal change is from lead-zinc down into copper mineralization—-the usual zonal change that occurs in many districts. In the Burke-Mullan portion of the district, on the other hand, lead-zinc ore does not pass downward into copper mineralization of the Sunshine type. Instead, pyrrhotite appears in depth while the tenor in lead and zinc declines. The change occurs at increasingly greater depth away from the Gem stocks, deepening irregularly by some 3000 ft within two to four miles. As noted by Crosby, biotite, grunerite, and garnet appear in the deep zone. The marked difference between this apparent zonal change and the more nomal change to a copper zone is quite explainable if already existing pre-Cambrian veins have been locally metamorphosed by a Tertiary intrusive. The chief obstacle to this explanation is the evidence that mineralization cuts Laramide intrusives, but evidence on this point is conflicting as indicated by Crosby's observations and summary. This is not the first instance of a problem in determining the time-relationship of mineralization to a spatially associated intrusive. At the Noranda mine veins of chalcopyrite extend into a diabase dike which apparently cuts the ore, although Price2 concludes that the ore is later. However, at the Normetal mine diabase of a similar dike is thought3 to intrude the orebody but is cut by stringers of chalcopyrite. In the Sullivan Mine, B. C.,4 galena follows a fracture in a larnprophyre dike which, itself, cuts the main orebody. In the Sudbury district dikes of olivine diabase are clearly younger than the nickel ore, yet where they cut the Creighton orebody they contain stringers of chalcopyrite. In the laboratory, Hawley5 has developed veinlets of sulfide (chalcopyrite) it] silicate gangue by heating specimens of ore in a stream of H2S at 410 °C. From this and other evidernce. it seems clear that sulfides can be transferred from one site to another — at least through short distances — at temperatures well below their melting points. It would seem then that even if sulfide Mineralization in the Gem stocks can be shown unequ ivocably to be later than the intrusive the possibility of "remobiliza tion" need not be more than local. Thus the zonal relationships are quite in accord with a pre-Cambrian age for original deposition of the lead, zinc, copper, silver, and uranium in the Coeur d'Alene district. REFERENCES 1. A. Silverman, A. Long, and J. L. Kulp: Discussion of: The Gem Stocks and Adjacent Orebodies, Coeur d'Alene District, Idaho. Mining Engineering, May 1960, pp. 470-471; AME Trans., 1960, vol. 217, p. 117. 2. Peter Price: Geol. & O. D. at the Home Mine, Noranda, Quebec. Can. Inst. M & M Bull 263, 1934, p. 108; also,Trans. CIMM 1939, pp. 108-140. 3. w. L. Brown Nometal Mine in structural Geology of Canadian Ore Deposits, Montreal, 1948, p. 690. 4. C. O. Swanson and H. C. Gunning: Geology of the Sullivan Mine. Can. Inst. Mining & Met. Trans. vol. 48, 1945, p. 653. 5. J. E. Hawley: Heat Effects on Sulphides and Possible Applications. Univ. Toronto Studies, Geol. Ser. No. 46, 1941, p. 34.

Jan 1, 1961

By AIME AIME

WHEN Russell B. Paul was born in Russell Gulch, Gilpin County, Colorado, that district was the state's leading gold producer. The son of Dr. Henry Paul, who had gone to Colorado from Missouri during the golden era following the Civil War, and had joined the Institute in 1889 when he was manager of the famous Aspen mine, young Paul's early life was steeped in a mining atmosphere from which developed his selection of mining engineering as a profes¬sion. After receiving his E.M. degree from the Colorado School of Mines in 1902, Mr. Paul worked in Colorado and Honduras. Returning from Central America he was married to Mary Ellen Gilmour, daughter of a prominent Central City mining man;

Jan 1, 1943

By Hans Lundberq

WHEN geophysical methods were first employed in the search for ore deposits and oil accumulations, it was hoped that they would provide a direct means of locating such concentrations. Magnetized needles were used long ago in prospecting for magnetic iron ore, and soon after the discovery of galvanism in about 1790 attempts were made to find concentrations of valuable minerals electrically. Evidence indicating that the early geophyeical instruments were regarded merely as improved divining or dowsing rods is to be seen in the names "mineral finders," "ore finders," etc., that were applied to them. Today, appellations of this kind raise serious doubts in informed minds as to the intelligence and integrity of individuals advocating the use of such euphemistically named methods or instruments, for experience and research have shown that, geophysical, it is never a question of directly locating a given mineral but merely of delimiting its possible occurrence.

Jan 1, 1939

By C. L. HUNTZINGER

THE mine here described is in the Witbank district, a coal area of the Transvaal, about 100 miles north- east of Johannesburg. and is owned by the Witbank Colliery, Ltd. The plant has a capacity of 4000 tons per eight hours, and prepares five sizes of coal. The coal seam lies at a depth of about 200 ft. below the surface, and is reached by an inclined shaft sunk at an angle of 18° with the horizontal. Although the thickness of the coal seam varies from 10 to 14 ft. or more, only about a 7-ft. bench is mined. Mining is by the hord and pillar system. Bords are driven 18 ft. wide, with pillars measuring 18 ft. square. The mine is laid out into four sections, each sewed by a main haulage way from the shaft. Arc-wall machines are used for cutting the coal. but all loading is done by hand. Native labor is employed under the supervision of white miners, who do the required blasting. The workings are practically free from gas and water, and very little timber is needed.

Jan 1, 1931

By AIME AIME

IN furtherance of the policy of acquainting those members of the Institute who live at a distance from New York with all the details of administration, the thirty delegates sent by the local sections and the technical divisions were invited to attend the meeting of the Directors on Tuesday evening as well as the Directors' dinner immediately preceding. Including the Directors and officers, new and old, the members of the Papers and Publications Committee and the section delegates, more than 70 sat down at the dinner table in the Engineers Club. The attendance at the business meeting that followed was not quite so large, doubtless for the reason that the ladies' fashion show, held in connection with the informal dance, offered attraction that eclipsed that of watching the wheels of Institute business go around.

Jan 1, 1930

By THOMAS S. MENNIE

ON GORE Mountain, about four and a half miles, southwest of the village of North Creek, Warren Co., N. Y., are the Barton Mines. Here is the largest known deposit of garnet in the world. This property is owned by H. H. Barton &: Son Co., of Philadelphia, and is being worked under lease by Barton Mines Corpn. North Creek is the terminus of the branch of the Delaware and Hudson R..R., which runs into the

Jan 1, 1925

By AIME AIME

ALMOST as many attended the annual dinner this year as last, when the presence of Mr. Hoover was such an attraction that almost two-thirds more than had ever attended before were present. Only by putting the late comers at tables in the balcony could everybody be accommodated. Past President De-Golyer was the toastmaster and in opening the post-prandial exercises referred to the regrettable fact that this was the last of the long series of dinners which have been held at the Waldorf, as the hotel will be torn down to give way to an office building before another year. To the delight of the gathering "Oscar" appeared and, in a delightfully brief but characteristic speech, referred to the long association that had existed and hinted that a new Waldorf-Astoria may arise, where the Institute could continue to gather annually in an enlarged replica of the room they had met in so long. Before taking up the presentation of the medals, Mr. DeGolyer referred to the Institute's "Legion of Honor," the 34 men who have been members continuously for over fifty years. For various reasons only five of them, W. S. Ayres, F. G. Corning, Henry D. Hibbard, A. F. Schneider and Arthur Thacher, could be present. They were all seated at the speaker's table, and W. S. Ayres, 56 years a member, as the dean of the group, was called on to respond for them all. He said: "The introduction I have just received would indicate that this particular group of men to which I belong is considered by the chairman to be a group of real antiques. Possibly you are questioning the accuracy of his judgment. I hope you are, although there may be some first-sight evidences tending to substantiate the view held by the chairman.

Jan 1, 1929

By Russell Webster

In having maintained production for more than 40 years Arizona's Magma mine is unique in a mineral district that includes several major copper mines. Other past and present producers in this area are Miami and Inspiration at Miami, the Old Dominion in Globe, the Ray mine in Ray, and to the south the new San Manuel mine near Tucson. Magma's production of copper, silver, gold, and some zinc has come from nearly parallel east-west striking mineralized faults, one called the Main or Magma vein and the other the Koerner vein, about 1100 ft to the south. This vein system has been prospected and partially mined for some 9000 ft horizontally and 4800 ft vertically. In ascending order from the deepest exploration level, the Main vein cuts Pre-Cambrian schist, Pre-Cambrian Apache Group, Post-Devonian diabase, and Devonian, Mississippian, and Pennsylvania limestones. Until 1950 very little ore was obtained from replacement mineralization.

Jan 10, 1958

By Joseph Newton

MUCH the same story can be told about the copper industry for the year 1944 as for the three preceding years. Operators report few or no technical changes at their plants and the main endeavor has been to maintain high production with existing equipment. No large new installations have been made to increase plant capacities and apparently over-all copper production has passed its maximum. The present decline in copper production results partly from the severe labor shortage. As is true of most industries; the outstanding fact about the copper industry during the past few years has been its tremendous and sustained production which has been maintained in spite of serious shortages in material. labor, and technical personnel. The figures in Table I give a concrete example of how production has been increased at one large smelter in the United States-the Garfield plant of the American Smelting and Refining Co. at Garfield. Utah. These figures, reported by W. G. Rouillard. superintendent. give the production of the Garfield plant for the five years 1940-44 inclusive. The total blister production

Jan 1, 1945

By R. E. Reed-Hill, W. H. Hartt, W. A. Slippy

An unusual form of double kinking has been observed at the ends of {1121} twins in deformed zirconium. These kinks lie partly outside of the twin and partly inside. While they are undoubtedly closely associated with accommodating the twinning shear into the matrix, they are apparently closely related to other important aspects of twin growth. A mechanism is proposed for {1121} twin growth involving interactions between 1/3 (1120) dislocations in the bend planes and twinning dislocations. It is also shown that boundaries without long range strain fields develop at the tapered ends of the twins. The {1121} twins can, therefore, grow without forming high-energy noncoherent twin boundaries containing large numbers of closely spaced twinning dislocations. NUMEROUS investigators have indicated that slip is often closely associated with deformation twinning. An example is twin accommodation kinking,1-3 where dislocations form bend planes and permit accommodation of a twinning shear within the parent crystal. Another is the incorporation of slip dislocations into twins, as proposed by Sleeswyk and verbraak4 and Ishii and Kiho5 for iron and ß-tin, respectively, and observed in hcp metals by Price.6 In addition, it has been shown that shear discontinuities exist at the points of twin intersections in zinc,7 magnesium,8 titanium,9 ß-tin,10 and bismuth," where the continuity conditions for twin intersections, originally proposed by cahn,12 are not satisfied. A similar situation occurs for zig-zag (1121) twins in zirconium13 and ?-phase silver-aluminum alloys,14 where the twinning shears of the two component twins are not parallel. In all these latter cases additional deformation by slip is believed to accommodate the twinning shear discontinuity. The present paper is concerned with a newly observed aspect of the slip and twinning interrelation, in which two kinks, one inside the twin and the other external to the twin, are formed. These kinks, observed in conjunction with (1121) twinning in zirconium, form to accommodate the twinning shear. A model has been constructed explaining the growth and accommodation of (1121) twins in terms of these kinks. This mechanism may be significant since it is concerned with an important twin mode, which occurs not only in zirconium but also in titanium and hafnium. The practical significance of (1121) twinning has been adequately demonstrated. At 77° K the high ductility of zirconium containing a large number of grains unfavorably oriented for slip is primarily due to (1121) twinning.'5 Also, (1121) twins nucleated at 77°K may grow during further deformation at room temperature. This growth can greatly increase the transverse ductility15 as well as produce large mechanical hysteresis effects.= EXPERIMENTAL PROCEDURE Arc-melted, sponge zirconium plate previously described17 was prestrained 0.65 pct at 77° K by cold-rolling to introduce {1121} twins into the structure. Tensile specimens were cut with axes normal to the plate rolling direction. These specimens were pulled in tension to near the point of failure in an Instron machine at room temperature at a cross-head speed of 2 x10-2 in. per min. This additional deformation caused growth of the twins nucleated by prestrain. Deformed specimens were then prepared for metallo-graphic examination. This included an anodizing treatment18 that made the surfaces sensitive to polarized light, permitting small lattice rotations to be revealed. EXPERIMENTAL RESULTS Nature of the Twin-Kink Band Structure. Fig. 1 is a photomicrograph of a typical specimen after prestrain at 77° K. The structure is characterized primarily by long, narrow, parallel sided (1121) twins which norma1ly traverse the entire grain. Fig. 2 shows several (1121) twins after additional straining at room temperature. These lie near the center of the polarized light photomicrograph and are inclined upward to the right. It is evident that this latter deformation has resulted in appreciable twin growth. The dark regions extending from the ends of these twins are accommodation kinks. The difference in reflected light intensity indicates the

Jan 1, 1969