Search Documents

By J. F. Nester, J. B. Schroeder

COMPOUNDS of rare-earth and iron-group elements are of technical interest because of their unusual magnetic properties. To date, however, all magnetic measurements1-4 have been made with polycrystalline, often polyphase, samples. For the measurement of anisotropic properties, single-crystal samples are necessary to avoid the averaging effect of randomly oriented grains. The purpose of this note is to describe a technique with which we have grown relatively large single crystals of YCo5, NdCo5, DyCo5, and "YFe9". Crystal growth of these materials is complicated because: 1) the binary equilibrium diagrams are, in general, not well-established; 2) in those cases where phase-equilibrium data are available, the compounds of interest are generally formed by peritectic reaction; 3) the molten component metals are chemically very reactive, making contaminaticn of the melts by the crucible material a serious problem. Techniques such as arc or levitation melting followed by strain annealing have been tried5)' in the past with these materials, but with little success because of the peritectic reactions and the inherently poor process control. For this reason we chose to use the zone-melting technique of Mason and cook7 for our work, since past workers8 have had some success in preparing single crystals of peritectic compounds by this method.

Jan 1, 1965

By A. G. H. Andersen, A. W. Kingsbury

SILICON bronzes containing iron are used to a considerable extent in industry, under the trade name of P.M.G. alloys. Various classes of wrought alloys fall in the composition range 1.5 to 3.5 per cent silicon, and 0.5 to 2.5 per cent iron. Castings may contain as much as 6 per cent silicon and 3 per cent iron at present. The constitutional diagrams of these alloys are thus of considerable practical importance. Copper-silicon-binary alloys have been thoroughly investigated by a number of workers, the latest reports being those of C. S. Smith' and of A. G. H. Andersen .2 Although much work has been done on iron-copper alloys,3 recorded investigations on the copper-rich copper-iron binary constitutional diagram are not numerous. Tammann and Oelsen4 determined the solubility limits of iron in copper by means of magnetic measurements, and found that the solubility of iron in copper amounts to a fraction of one per cent at 400°C., increasing slowly to one per cent at 800°C. From 800°C., the solubility increases rapidly and attains 4 per cent at 1100°C. Hanson and Ford," using electrical resistivity measurements and the microscope, determined a somewhat different solubility limit. Of earlier X-ray works on the copper-iron system, very little has been published. The work by Bradley and Goldschmidt6 on copper-iron-aluminum alloys includes some information on the copper-iron binary. These investigators conclude that substitution of iron in the copper lattice decreases the spacings, which is contrary to the evidence of the present work. Hanson and West7 have investigated the ternary alloys of copper with iron and silicon. Although their diagrams are valuable contributions to the understanding of these alloys, they did not recognize the kappa phase,1,2,7,8 and their diagrams do not everywhere conform to the phase rule. The present work contains a check by means of X-rays of the solid solubility limit of iron in copper, and an X-ray investigation of the ternary-phase diagram, which, owing to present conditions, it became necessary to curtail considerably. PREPARATION OF SAMPLES Castings weighing about 75 grams were melted under vacuum. The charges were made up of ingot iron, copper cathodes from Laurel Hill, and refined silicon supplied by the Electrometallurgical Co. Alundum crucibles were generally used. The exceptions were alloys 77 and 78, which were melted in graphite crucibles. The ingots were annealed at 800°C. for one week, then samples were cut for chemical analysis. Longitudinal sections of the binary alloy ingots were hammered into plates h in. thick. Wherever possible, these plates were homogenized at temperatures ensuring

Jan 1, 1942

By I. J. Bear, H. W. Paxton

Studies have been made of the method of propagation of yield in iron single crystals in the range of 205' to 295OK by microscopic and X-ray techniques. 'The results show yielding in two stages, of which the second corresponds closely to the Lüders extension in polycrystalline iron. IRREGULAR macroscopic markings On the polished surface of a polycrystalline mild steel test piece during the lower yield extension were first observed by Liiders.' The lower yield stress was not very constant. Sylvestrowicz and Hall2 showed that it was possible to obtain a constant lower yield stress by using a specimen in the form of a moderately flexible thin strip; the macroscopic markings in this case then appeared as a band of deformation (Lüders' band) which propagated steadily from one or occasionally

Jan 1, 1956

Jan 1, 1971

By O Gutsche, Fuerstenau D. W., R. Ravikumar

Six minerals and one ore, namely, barite, dolomite, galena, limestone, quartz, quartzite and taconite, were ground in single-particle comminution mode in a rigidly mounted roll mill with different levels of energy input. Grindabilities were determined from the median size of the self-preserving product size distributions, which was taken as a measure of the fineness of the ground material in an empirical energy-reduction ratio relationship. These values reflect the inherent resistance of the solids to mechanical size reduction that are least distorted by particle-particle interference effects, grinding characteristics, energy efficiency of the milling system employed and the extent of the fineness specified.

Jan 1, 1992

By J. M. Shafer

Jan 1, 2005

By Thomas E. Marshall, Anthony T. Iannachione, Leonard J. Prosser

The location and time of 2,007 microseismic emissions from a limestone mine in southwestern Pennsylvania were compared with the development of mine faces and the characteristics of the mine layout. Based on analyses of these results, the occurrence of roof failure zones appears to be associated with certain characteristics of the mine plan. It was determined that significant relationships exist between the intensity of the microseismic activity and the scale of the roof failures Microseismic activity associated with these roof falls occurs In distinct episodes, with the final failure event occurring during approximately a 12-hour period. Each roof fall episode appears to be composed of dozens of distinct roof beam failures. As each beam fails in shear and tension, tens to hundreds of audible noises representing rock fracturing or bedding plane separation can occur. While every roof fell can be viewed as unique, certain mechanistic similarities can be realized through careful observation and monitoring of these complex systems. Understanding these similarities in characteristics allows mine personnel to design the most effective and efficient control technique.

Jan 1, 1938

Jan 1, 1936

Jan 1, 1958

Jan 1, 1958

Jan 1, 1967

PROF RICHARD ÅKERMAN Stockholm, Sweden DR FRANK DAWSON ADAMS Montreal, Canada PROF HATON DE LA GOUPILLIERE Paris, France SIR ROBERT A. HADFEILD London, England HERBERT C. HOOVER Leoben, Austria ROBERT W. HUNT Chicago, ILL JAMES FURMAN KEMP New York, N.Y. PROF HENRI LOUIS LE CHATELIER Paris France EZEQUIEL ORDONEZ Mexico City, Mexico ALEXANDRE, POURCEL Paris, France PROF RICHARD H, RICHARDS Boston Mass. JOHN E. STEAD Middlesborugh, England PROF DIMITRY CONSTANTIN TSCHERNOFF St Petersburg, Russia PROF TSUNASHIRO WADA Tokyo, Japan CHARLES D WALCOT Washington D.C.

Jan 1, 1923

Abbott, Franklin E. Adgate, Frank Aertsen, G. Aid, Kenneth Albert, H. I. Alexander, D. B. W. Allan, Wm. G. Allen, R. 0. Allen, Roy H. Aller, Mr. and Mrs. F. D. Altmayer, Maurice Ambler, Harry A. Ambrose, A. WV. Ammon, Mark A. Ammon, Mr. and Mrs. Robt. Anderson, George H. Anderson, Mr. and Mrs. L. D. Andros, S. 0. Appleby, W. R. Archer, R. S. Armitage, Paul Arobb, Alden D. Arthur, Walter Ashman, A. 0. Atkinson, R. H. Aupperle, J. A. Austin, D. F. Avery, G. E.

Jan 11, 1919

By Alexander L. Holley

Jan 1, 1879

Page Foreword—H. Foster Bain........................ 9 Letter of Transmittal—F. Julius Fohs...................11

Jan 1, 1927

The 116th (New York) Meeting of the Institute will be held in the third week of February, 1918. The Committee on Papers and Publications has set Dec. 1, 1917, as the closing date for the receipt of .manuscripts intended for this meeting. Manuscripts must be received by the Secretary on or before this date. If they are sent through members of the technical committees they must be sent to those committees enough in advance of the time to be forwarded and in the. hands of the Secretary by the time specified.

Jan 11, 1917

By Just G. D

The results of a geostatistical analysis of geochemical data obtained from field measurements are described in the paper. Q values derived from seismic signal rise times for different travel paths in the rock masses were used in the study. Cross-hole seismic measurements made at surface and underground sites formed the basis for the work. Geostatistical estimation of average l/Q values for area of the rock were compared with geological interpretions of rock type distributions. Reasonable correlations were obtained between the two methods of rock quality estimation.

Jan 1, 1988

By J. B. Ackerman, C. S. Bucans

The Sunshine Mining Co. has recently started up its new silver refinery in Kellogg, ID. The new plant recovers silver anc copper values from a high grade tetrahedrite concentrate using hydro- metallurgical processes. The plant and process are both new and have gone through the initial startup phase during the first six months of 1985. The full scale plant was developed from laboratory test work. While the metallurgy of the process worked as expected, the material handling problems were difficult to over-come. As might be expected, those parts of the plant that represented available technology started up easily, while the parts that represented new technology presented the most difficulty. Topics covered in this paper include: 1) insufficient type and amount of agitation in the leach vessels, 2) discharge of a non- homogeneous slurry from the leach vessels, and 3) problems associated with very low flow rates in slurry lines.

Jan 1, 1987