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By S. E. Maddigan, B. R. Zimmerman

Most metallurgists are well acquainted with the contributions already made to the study of metals by the use of X-rays. On the one hand, the radiographic method is constantly becoming of increasing importance as a nondestructive testing procedure, while on the other hand the techniques of X-ray diffraction have made important contributions to the fundamental knowledge in studies of phase diagrams, stress conditions, and so forth. A new, and as yet insufficiently appreciated, tool exists in the application of microradiography to alloy structures. This new procedure in many respects bears the same relation to microscopic investigations as does macroradiography to the gross inspection of metal surfaces. However, where macroradiography is used ordinarily to determine the soundness of the metal structure, this new method can be used not only to investigate micro-un-soundness but also to examine the distribution of the constituent elements within the body of the alloy. When combined with the normal procedures of microscopy, this offers a technique of great potential power. It is intended in this paper to present a few examples of copper-base alloys demonstrating the additional knowledge obtained from the microradiographic method. The detection of micro-unsoundness is demonstrated in Fig. I for a sample of cartridge brass as cast. The sample ap- peared quite sound when viewed under the microscope, but in reality was thickly populated with minute voids. This application of the method conforms in every way to conventional large-scale radiography and has been used to facilitate production of metal for vacuum devices.' The true potentialities of the technique are revealed by comparison of Figs, 2a and 2b, which are respectively a photomicrograph and a microradiograph of a cast alloy of 80 per cent Cu, 10 per cent Sn, 10 per cent Pb. The remarkable difference in appearance provides some concept of the additional information this method may yield when used as an auxiliary to microscopic studies. Fig. 2a shows two phases of the copper-tin system plus segregated_ lumps of lead. Fig. 2b, on the other hand, shows with exceptional clarity the actual dendritic growth of the metal crystals during solidification. The practice of microradiography depends upon the laws of absorption of X-rays. This subject has been reviewed thoroughly in recent papers,l,2,3 but for clarity a brief resume will be given here. As is well known, when a beam of X-rays is transmitted through a, layer of homogeneous material, the intensity is reduced according to the relation: where Il is the transmitted intensity, I0 is the incident intensity, µ1 is the linear absorption coefficient of the material, t1 is the thickness of the material.

Jan 1, 1944

By M. Duclos, A. Sawatzky

A simple model has been developed which describes the steady-state solute distribution in Ti-H type systems above the eutectoid temperature in the presence of a temperature gradient. The solute distribution is dependent on the shape of the phase boundaries. An interesting result, and one that is not observed at steady state in thermal diffusion below the eutectoid temperature, is the existence of a two-phase region. The heat of transport for hydrogen in a titanium, Q*a, over the temperature range 275" to 650.C is determined to be 4500 * 230 cal per mole. The heat of transport for hydrogen in B titanium, QB* over the temperature range 320" to 590.C is found to be 630 ± 200 cal per mole. It is also shown that thermal diffusion provides a method by which phase bounduries above the eutectoid may be determined in Ti-H type systems. IN modern technology materials are being used at constantly increasing temperatures under greater temperature gradients. Thus atomic migration in metal alloys due to a temperature gradient (thermal diffusion) may in some cases occur to an observable extent. The thermal diffusion of hydrogen in zirconium has in recent years received considerable attention1-' because of the use of zirconium alloys in nuclear power reactors. The thermal diffusion kinetics below the eutectoid (547°C) are fairly well understood. At steady state the solid solution, a, and hydride, 6, phases are completely separated with the hydride precipitating at the lower temperatures. No experimental work has been carried out in the a + B region although Droege4 suggested that a complete separation of the two phases, as observed at temperatures below the eutectoid, might not always occur. In the present investigation a simple model has been used to determine the steady-state solute distribution under a temperature gradient in Zr-H type systems heated above the eutectoid temperature. The solute distribution is shown to be dependent on the shape of the phase boundaries in the constitutional diagrams and several typical cases are discussed. The model has been applied to Ti-H. This system was chosen in preference to Zr-H because of its much lower eutectoid temperature (-300°C as compared with 547.C), thereby reducing experimental errors due to oxidation and hydriding. The heats of transport for hydrogen in the a and B phases of titanium also have been determined since they were required to compare the proposed thermal diffusion model with experiment. THEORY In the presence of a temperature gradient the atomic flux in a single-phase region of a two-com-ponent system of which the atoms of only one component are diffusing is given by:' J = - U\dx + RT3 dx) which can be written as: j-D(dn/dt +Q*n/RT2)dt/dx [11 J - -D\dT + RT2)dx [1] where D = diffusion coefficient, n = solute concentration, T = absolute temperature, R = gas constant, dT/dx = temperature gradient, and Q* = heat of transport. At steady state (J = 0) Eq. [I] leads to the solute distribution: n = noexp Q*/RT where no = a constant depending on total solute content. The heat of transport Q* can be experimentally determined from the steady-state distribution. In the present paper we shall determine the solute distribution in systems having the constitutional diagram exemplified by Ti-H shown in Fig. l.' As shown, N,(T) and NB(T) are the equilibrium solute concentrations in the a and 0 phases at temperature T. Lines AA' and CC' define the region of interest to us. The following assumptions are made: 1) Steady-state conditions prevail. 2) In a single-phase region all points on an isotherm have the same thermodynamic potential so that the composition over an isotherm is uniform. If a two-phase region exists, thermodynamic equilibrium is found only at phase interfaces. However, we assume the component of the concentration gradient along an isotherm to be small so that the composition in each phase is approximately the same as at the interface and is given by the constitutional diagram, Fig. 1. 3) There is appreciable diffusion of only one component. 4) We shall consider only the case where Qa*, QB*, and Qg*, the heats of transport for solute diffusion in the a, B, and 6 phases, respectively, are positive. This has been observed for the thermal diffusion of hydrogen in zirconium3 and titanium.10 We will show that the steady-state solute distribution above the eutectoid is primarily determined by the heats of transport and the temperature dependence of Na(T) and Np(T). It may be quite different from the steady-state distribution below the eutectoid. For example, we will see that, under certain conditions,

Jan 1, 1970

By Albert Hill Fay

IN giving a sketch of the geology and mining of the tin-deposits of Cape Prince of Wales, a short description of the geographic and climatic conditions may be of special interest on account of this being a part of the world of which very little is known, even by the reading public. As shown in Fig. 1, the location of the Cape is lat. N. 65° 35' and long. W. 168°. It is bounded on the north by the Arctic ocean ; on the west by Bering strait and on the south by Bering sea. It is the western-most point of the mainland of North America, and to the west, across the strait, one can see East Cape, Siberia, which consists of a rugged, steep coast of granite cliffs. The climatic conditions are of interest because of the part they have had in the surface geology, and also because they affect mining from an economic standpoint. In connection with the climate and geography, it does not seem out of place here to quote a few lines from the prologue of The Wandering Jew, written by Eugene Sue, under the caption '1 The Land's End of Two Worlds."

Sep 1, 1907

By Richard H. Siller, Rex B. McLellan

A model for interstitial solid solutions has been considered in which a repulsive Potential exists between interstitial atoms in the solvent lattice. It has been shown that this model is consistent with the thermodynamic Properties of certain interstitial solid solutions. The model is then applied to the calculation of the variation of the diffusivity of carbon in au-tenite with composition. Although the energy levels at the saddle point, and thus the absolute values of dif-fusivity, cannot be calculated, it is shown that by taking the repulsive interactions between the diffusing atoms into account the functional form of the dependence of diffusivity on solute concentration can be derived. ThE composition dependence of the diffusivity, D, of carbon in austenite at a given temperature is well-known.'-3 smith3 tried to reconcile the observed composition dependence of D at 1000°C with the previously observed4 composition dependence of carbon activity using equations for D derived by arken5 and Fisher, Hollomon, and Turnbull,6 but was unsuccessful. In this paper we shall modify the approach of Fisher et al. by considering the "blocking" model7 for interstitial solid solutions, based on concept due to Speiser and Spretnak,' in which a repulsive potential exists between interstitial solute atoms in the solvent lattice, causing a certain number of interstitial sites to be "blocked" from occupancy by further solute atoms. We shall thus be able to describe the intimate relationship between the composition dependence of carbon diffusivity, a kinetic phenomenon, and the composition dependence of carbon activity in austenite. THEORY Consider for convenience one-dimensional interstitial diffusion in an fcc lattice in the [loo] direction. Fig. 1. Assume that solute atoms occupy octahedral sites only.7,9'10 These octahedral sites are located on {lOO} planes a/2Å apart. A solute atom, A, occupying an octahedral site on a {100 } plane denoted by 2, has twelve nearest-neighbor octahedral sites: four on plane 1, four on plane 2, and four on plane 3. Diffusion occurs when there is a net flux of solute atoms, through an imaginary plane shown with dashed lines, from plane 2 to plane 3. Fisher et al6. use the concept of activated complexes, as given in the theory of absolute reaction rates." They show that the number of solute atoms per cubic centimeter per second which pc — Fig. 1-Diagram showing the arrangement of octahedral sites (x) in the fcc lattice. pass in the direction of diffusion from activated to new interstitial position is: ?where C is the concentration of the solute in atoms per cubic centimeter, l/m + is the fraction of new interstitial positions corresponding to motion in the forward diffusion direction (transmission coefficient), ?F* is the free-energy difference between the activated complex and the reactants when each is in its standard state at the temperature of the reaction (independent of temperature and composition in the case of carbon in austenite), y is the activity coefficient of the solute species, and, finally, ym is the activity coefficient of the activated complex (assumed constant). The flux of atoms moving in the forward direction through an area of 1 sq cm perpendicular to the direction of diffusion is therefore: m+ Ym l ' atoms per second where is the distance between planes. The blocking model states that a nearest-neighbor octahedral site of a given solute atom has a probability, f, of being inaccessible to other solute atoms. The number of available sites for diffusion on a given plane will, therefore, depend on f, which is constant, and Nu, the number of solute atoms on that plane. The effect is to have more available sites in the diffusion direction, thereby increasing the net flux of solute atoms. This is reflected in the transmission coefficient, l/m. To calculate the transmission coefficient for solute

Jan 1, 1970

Abdul-Ahad. A., Student, Montana School of Mines, Residence Hall Butte, Mont. '39 Abramovits, Charles, Student, Case School of Applied Science Cleveland, Ohio. '37 Abreu, Ovidio M., Student, Univ. of Nevada Reno, Nev. '38 Acker, Voscoe, Student, Agricultural & Mech. College of Texas College Station, Tex. '39 Adams, Albert, Student, New Mexico School of Mines Socorro. N. M. '38 Adams, Charles W., Student, Michigan College of Min. & Tech Houghton, Mich. '39 Adams, Hugh T., Jr., Student, Univ, of Oklahoma Norman, Okla. '39 Adams, Jack L., Student, Univ. of Oklahoma Norman, Okla. '39 Adams, Jack M., Student, Univ of Alaska College, Alaska. '39 Adams, Lewis J., Student, Agricultural & Mech. College of Texas, Box 2514, College Station, Tex. '39 Adams, Robert E., Research Engr., Battelle Memorial Inst Columbus, Ohio. '38 Adamson, George M., Jr.. Student, Univ. of Utah Salt Lake City, Utah. '39 Adkisson, J. F., Jr., Student, Agricultural & Mech. College of Texas, Box 1003, College Station. Tex. '38

Jan 1, 1939

By David T. Day

IN 1897 I published a proposed explanation t for the variation in color and specific gravity of Pennsylvania oils. A resume of this subject was also presented at the First International Petroleum Congress, in Paris, in 1900. Since that time much experimental work bearing upon this explanation has been carried on by myself, in the United States Geological Survey, and under my direction, by Dr. J. Elliott Gilpin, Marshall P. Cram, and 0. E. Bransky, at the Johns Hopkins University. The experimental results thus accumulated seem to throw considerable additional light upon the variations in color and specific gravity of petroleum, as found in different parts of the world, and also upon the variations in chemical composition. Therefore, it seems as if a, summary of the evidence thus obtained might be of value to those members of the Institute who are interested in the examination of oil-fields. The summary is here presented for that purpose. The phenomenon has often been observed in many oil-fields that oils of different color, specific gravity, and chemical composition may be found within short distances of each other. A conspicuous example of this is the occurrence at Jennings, Welsh, and Anse la Butte, La., of petroleum chemically somewhat similar to Russian petroleum; that is, characterized by the presence of naphthenes. Another characteristic is the presence of considerable percentages of asphaltic compounds, sufficient in quantity to disguise the presence of solid paraffin wax, and perhaps also to render that paraffin wax more soluble * Published by permission of the Director of the United States Geological Survey. 1 Proceedings of the American Philosophical Society of Philadelphia, vol. xxxvi., No. 154, pp. 112 to 115 (January, 1897).

Jun 1, 1910

By R. F. Burdyn

The inadequate use of centrifugation to economically recover solids from weighted drilling fluids reflects the need for better equipment and techniques for this putpose. Laboratory studies in the development of an improved separator are described in which an operating equation is derived and tested. Results show that the concentric cylinder geometry employed effectively separates bnrite from a suspension and that the operating equation provides a good approxinmtion for scale-up. INTRODUCTION Our current drilling technology frequently requires a high-density drilling fluid obtained by addition of barite. In the course of drilling, formation solids which are too fine to be removed either by screening or settling become suspended in the drilling fluid and gradually the volume of solids in the mud increases. The volume fraction of solids must be limited (if a satisfactory set of rheological parameters are to be maintained). A centrifugal separatorprovidesan economical way of accomplishing this. The barite recovery process can be considered as a separation of two solids. One, the light solids, composed of formation and added solids, has a specific gravity of 2.6 to 2.7; the other, barite, has a specific gravity of 4.2 to 4.3. This density difference, plus the fact that the average light-solids particle size is much smaller than the average barite particle size, permits separation by a centrifuge. In drilling fluids some of the coarse particles of the light-solids-range will settle faster than fine particles of the barite-particle range. As a result a complete separation of the two species is not possible. since the object of the process is not merely recovering the maximum amount of barite but includes as well removing the maximum amount of light solids, an optimum barite recovery efficiency exists. From a practical standpoint this optimum cannot be determined in the field for each drilling fluid system, and in practice the separation is less than optimum, with some sacrifice of barite. Drilling technology has included centrifugal separators for barite recovery for more than a decade. Results have been reported by a number of investigators indicating that the process is practical and economica1. l-4 The decision to use a centrifuge is based on economics in which direct cost savings and the indirect benefits in rig time derived from improvement of the drilling fluid are important factors. One would expect that centrifugal separation of barite from drilling fluids would significantly affect barite consumption; however, this is not the case. The Minerals Yearbook shows an annual domestic barite consumption in the drilling industry of nearly 1 million tons.5 By rough estimate there are perhaps 80 separators presently in field use. Assuming half of these in use at any one time, operating an average of four hours per day, at recovery rates averaging 3,000 Ib of barite per hour, total annual recovery is about 90,000 tons. This is less than 10 per cent of he total barite used. I conservatively estimate that barite consumption in drilling operations can be reduced by 30 per cent through greater utilization of centrifugal separators. To encourage more widespread acceptance of centrifugal separators in the drilling industry, improved equipment and techniques would be very desirable. The present paper, covering theory and results obtained from a laboratory model, is the first in a series on he development of an improved mud separator for field use. THE CONCENTRIC CYLINDER GEOMETRY AS A SEPARATING DEVICE Consider the geometry shown in Fig. 1, consisting of two concentric cylinders separated by an annular space. These are arranged so that the outer cylinder is fixed and the inner one can be rotated about its axis on shafts sealed against the ends of the outer cylinder. If the outer cylinder is fitted with openings at either end, the inner

Jan 1, 1966

By George C. Branner

STATE geological surveys have had an interesting development in this country. They first appeared more than a hundred years ago. The fact that they have persisted and are now an important part of most state governments indicates the basic need for state departments con-cerned with mineral problems. The number of state surveys in 1941 (43) is at an all-time high, as is the aggre¬gate appropriation for their support for the fiscal year 1940-'41 ($1,600,708). The first surveys, those of North and South Carolina (see Fig. 1), made their appearance in 1820-'30, but neither survived that period. During the next two decades surveys were created in twenty states, but only three survived. In fact, it was not until the decade 1900-'10, when eighteen surveys were created and only five abolished, that these agencies became firmly established.

Jan 1, 1941

By Charles Fettke

The deposits described occur in a belt starting 1 ½ miles east of Juncos and extending 6 miles in a southeasterly direction. They are of the contact metamorphic type, being associated with a limestone and calcareous tuff that is interbedded with andesite tuffs and andesites which have been invaded by a quartz diorite intrusion. Of the fire occurrences examined, the largest can be traced for a horizontal distance of 2000 ft. No mining has, been done, but some of the outcrops lead to the belief that deposits of commercial size are present. IN CONNECTION with the gathering of data for a report on the geology of the Humacao district of southeastern Porto Rico during the summer of 1916, under the auspices of the Scientific Survey of Porto Rico and the Virgin Islands, conducted by the New York Academy of Sciences, the writer had an opportunity to make a brief examination of the magnetite deposits of the eastern portion of the island. Inasmuch as these deposits have attracted some attention as possible future sources of iron ore, and as there is only scanty reference made to them in literature,1 a short description based on this reconnaissance survey was deemed to be worthy of record. The magnetite deposits of eastern Porto Rico occur in association with a belt of limestone, trending approximately S 53° E, which begins 1 ½ miles east of Juncos and can be traced for about 6 miles toward the coast. Four outcrops of magnetite were observed, which are designated

Jan 2, 1924

By E. J. Horwood

The varying physical character and large extent of the Broken Hill lode necesarily involve the employment of a variety of underground methods. The lode had its origin in an extensive fault plane traversing metamorphosed schists conformably, as a rule, with their beds of stratification. The underground waters carrying minerals in solution deposited their contents in the original cavities formed by the faulting action, and in the enlargements of these cavities due to dynamic forces brought to bear on the rocks, more especially on the hanging-wall side of the fault. This deposition was supplemented by metasomatic replacement of a portion of the original rock contents by the argentiferous sulphides of lead and zinc which form the staple products of the district. Although the orebody is practically continuous throughout the mines, its width varies greatly, ranging from a few feet to about 350 ft. The widest portions occur in conjunction with huge folds in the inclosing country rock, almost exclusively on the hanging-wall side. The ore in these folds pitches to the south in the southern half of the field, and to the north in the northern half; there are, however, undulations in these ore channels evidently due to compression of the rocks in the direction of the channels. In the earlier days, before the orebodies had been opened up, vertical cross-sections across these bulges in the hanging wall gave the lode the appearance of the "saddle formation," so well exemplified at Bendigo in Victoria; but subsequent development of the ore channels has long since proved that the formations in the two districts are entirely different. The depth reached by the zone of complete oxidation of the sulphides varies from about 259 to 550 ft, from the original outcrop, while partial oxidation extends in places below the 1,000-ft. level. The result of oxidizing influences has been the production of ore of every grade of cohesive-ness, from that of dry sand to that of hard compact rock. The methods of mining followed in this field, and even in individual mines, are varied in accordance with the character of the ore. The general practice of the field is to sink vertical shafts, generally on the foot-

Jan 1, 1916

By John Fritz

THE John Fritz Medal was presented to Ambrose Swasey of Cleveland, Ohio, in the Auditorium of the Engineering Societies Building, in New York, on April 23. Charles F. Rand, Chairman of the Board of Award, presided and, after speaking very briefly of Mr. Swasey, whose friend he has been for a great many years, ,introduced Gen. William Crozier, formerly Chief of Ordnance, U. S. Army, who spoke most entertainingly of, Mr. Swasey's accomplishments in designing and manufacturing instruments of precision, particularly for the use of artillery in range finding: Dr. William Wallace Campbell, Director of the Lick Observatory, and President of the University of California, described Mr. Swasey's, contribution to astronomical advancement by his notable development of the largest telescopes in this country.

Jan 1, 1924

By AIME

A present the colleges and universities are struggling to meet the responsibilities placed upon them by the return of the veterans from the armed forces to the educational institutions as well as the youth graduating from the high schools. The problems of meeting these responsibilities are complex and upon the shoulders of the educational administrators lies much of the burden. One of those educators who is in the midst of this situation is James Rowland Cudworth, dean of the College of Engineering of the University of Alabama and Chairman of the Mineral Industry Education Division, AIME, both for 1946 and 1947. He was born at Norwich, Conn., on Sept. 23, 1897, and like his father before him went to the Massachusetts Institute of Technology where he received his Bachelor's degree in 1921. His studies at MIT were mainly in the fields of geological and mining engineering. Why a New Englander studies mining is anybody's guess, but it may be due to a love of traveling to far places which so many New Englanders do. After graduating tinder the famed Waldemar Lindgren. Jim trekked to Mexico where he worked at Pachuca for the Cia. Real del Monte and at Charcas with the American Smelting and Refining Co.

Jan 1, 1946

By C. H. Li, R. J. Stokes, T. L. Johnson

The effect of alumina particles on the nucleation and growth of cracks through a silver- chloride matrzx has been investigated. It has been found possible to promote fibrous cracking in dispersion-strengthened silver, chloride under notch-impact conditions at temperatures at which silver chloride alone cleaves brittlely The modification) of fracture beIzavzor is thought to be due to the relaxation of hydrostatrc stress beneath a notch by the nucleation of cavities near alumina particles. In recent years, composite or dispersion-strengthened materials have been studied primarily to understand their high resistance to plastic flow particularly at elevated temperatures. Dislocation models have been developed with which it is possible to deduce with fair success the effects of interparticle distance, particle size, temperature, upon yielding and creep behavior.l-4 Much less attention has been paid to the fracture behavior of these materials (with the notable exception of common structural steels) and little is known experimentally about the manner in which inclusions affect the nucleation and growth of cracks through a matrix. Nevertheless a beginning has been made in connection with fibrous cracking in ductile matrices where inclusions appear to play an essential ro1e.5-7 During the severe localized plastic deformation which accompanies necking in a tensile test, cavities are believed to develop at inclusions; these cavities subsequently grow and coalesce by plastic flow until separation is complete. It is of interest to consider whether inclusions can affect fracture behavior under loading conditions which restrict the plasticity of the matrix itself (for example, cleavage under conditions of a high imposed strain rate at low temperatures). It is particularly interesting to study these effects in a solid which shows a spectrum of behavior ranging from fully ductile to semi-brittle behavior. Such a solid is silver chloride whose mechanical behavior depends sensitively upon temperature and strain rate.'," The present paper is concerned with a study of the influence of inclusions (in the form of alumina particles) on the fracture behavior of silver chloride loaded uniaxially at low strain rates at room temper- ature and also under notch impact conditions over a wide range of temperature. In particular, it will be shown that the alumina particles can exert a startling effect on the ductile-brittle transition temperature of notched silver chloride and that the magnitude and nature of the effect depends upon both the quantity of alumina and the shape of the alumina particles. 1. EXPERIMENTAL PROCEDURE 1.1 Materials Used. Silver chloride powder of analytical reagent (AR) quality having an average particle size 6 was supplied by the Mallinckrodt Chemical Works (st. Louis, MO.). Acid washed 900 mesh alumina powder, designated A38-900, was supplied by the Norton Co. (Cambridge, Mass.). This powder was added to silver chloride in two forms: a) the as-received condition in which the individual particles were of random irregular shape; their statistical average size was 7; b) in a condition in which each particle was spherically shaped by a fusion technique. In this case, the statistical average particle size determined with the optical microscope was approximately the same (about 5p) but electron micrographic evidence indicated that many ultra fine particles were present in the spheroidized powder. 1.2 Preparation of Composite Materials. Silver chloride-alumina composites containing 2.5, 5, and 15 pct by volume of alumina were produced by the extrusion of mechanically mixed powders blended in a ball mill for 24 hr at room temperature. The mixtures were compacted at 50,000 psi at room temperature in the form of billets 3/4 in. in diameter and 1 in. long which were then extruded with a 16:l reduction ratio at 370°C through a radius-type steel die having a 5 deg lead-in angle. An extrusion temperature of 370°C was selected to ensure that all composites had sufficient plasticity to be extruded. Apart from this general requirement, the choice was arbitrary. 1.3 Microstructure of Composites. Attempts were made to check the distribution of alumina metallo-graphically by polishing transverse and longitudinal sections of the extruded rod. Specimens were wet-ground to 600 emery paper and lapped successively with 5 and 0.25-p grades of diamond paste. They were etched for 10 sec in 10 pct sodium thiosulfate solution and lightly polished in concentrated ammonium hydroxide. The most effective way to render the alumina particles and grain boundaries visible was to radiate the surface with intense white light to decorate the grain boundaries and the particle-matrix interfaces photolytically.

Jan 1, 1962

By Henry M. Rowe

Professor Ruff's most illuminating paper' describing his extremely valuable investigation of the carbon-iron equilibrium diagram assigns definite temperatures to certain very important lines in the diagram, viz.: the eutectic temperature EB (Fig. 1) and the " near-eutectic " temperature E'B', but without indicating clearly enough the reasoning which warrants these assignments. These temperatures are of such primary importance that it is well to indicate the apparent gaps in the reasoning, in the hope that they may be filled in. In his diagram, Fig. 1, the point X and the liues B'D'lII represent the experimental results reached by Ruff and Goecke;a AB, AEB, and SE represent the liquidus, the solidus, and the solubility of the carbon in solid austenite in the absence of graphite according to Gutowsky,3 AB being also in accordance with Spiecker's data; S'E' the solubility of carbon in solid austenite in the presence of graphite according to Ruer and Iljin;5 GS the line A3 after Ooerens and Meyer; 6 and EBC the true eutectic line as inferred by Prof. Ruff from Gutowsky's data. B'D' is the carbon content found in cast-iron which had apparently saturated itself with carbon in the presence of the graphite of the enclosing graphite crucibles in which the determinations were made. From its straightiiess and its sharp inflection near 6.67 per cent. of carbon, the carbon content of

Jan 1, 1913

By W. L. Dennen, V. H. Wilson

THIS paper is a description of the opera¬tion and results of a Humphreys Spiral Silt Cleaning Plant at the Powderly Colliery of The Hudson Coal Co. during the first nine months of operation and follows a pre¬liminary description given at the Anthracite Institute in May, 1947, in a paper titled "Preparation of Anthracite Sift for Boiler Fuel in a Humphreys Spiral Test Plant" by H. H. Otto, V. H. Wilson and W. L. Dennen. This plant is considered a full size operating test plant and, like all new plants, numerous minor changes in the methods of operation have been made from time to time to secure the results desired. Views of the silt preparation plant and of the screening house are given in Fig 1 and 2. This plant consists of 48 spirals in 8 batteries of 6 spirals each, 36 of which were to be operated as primary spirals and the remaining 12 as secondary spirals. A brief description of the plant and its operation follows. The only material cleaned at the plant during 1947 was that carried in the underflow from the Thickener which handles the Breaker waste water. This underflow, amounting to approximately 2000 gpm of water and containing 12.6 pct of solids, is pumped .to vibrating screens where the plus 316-in. material is removed. (Fig 3). This oversize material drops into a pocket from which it is trucked to the run-of-mine

Jan 1, 1948

By T&apos Ke, ing-sui

NUMEROUS investigators have observed that internal friction accompanies cold-working of metals and the effect of annealing is to reduce this internal friction.1,2 However, - most of the experiments were made at high stress amplitudes and the principal purpose was to study the increase of internal friction as a result of the applied cyclic stress during measurement. In order to study the internal friction introduced by cold-working applied prior to the measurement, the stress level applied during the measurement of internal friction must be sufficiently small. The results of measurement are significant and can be used for a base of comparison only when the applied cyclic stress is so small that the internal friction is independent of stress amplitude. Internal friction of cold-worked metals under small stress level has been studied by a number of workers8 -" he internal friction was measured around room temperature with a frequency of vibration of the order of kilocycles per second. The purpose of this paper is to report a study of the change of internal friction when severely cold-worked aluminum was annealed at successively higher temperatures until it was completely recrys-tallized. The measurements of internal friction were made over a range of temperature extending from room temperature up to the temperature of prior anneal. The frequency of vibrations used was about one cycle per second. The apparatus used for the internal friction measurements to be reported in this paper was a torsion pendulum with the specimen in wire form as the suspension fiber. The description of this apparatus and the method of measurement have been previously given.7,8 The applied stress was sufficiently small SO that the magnitude of internal friction is independent of stress level at each temperature range concerned. Corresponding to this stress the maximum shearing strain on the surface of the specimen is of the order of l0-5 and lower. The in- ternal friction (Q-1) is reported as 1/p times the logarithmic decrement. Internal Friction Versus Temperature of Anneal: Fig. 1 shows the internal friction measurements performed upon 99.991 pct aluminum subjected to 95 pct reduction in area. The final diameter of the wire is 0.033 in. This figure gives a general survey of the effect of temperature of anneal and of temperature of measurement. The internal friction of the cold-worked specimen was first measured at room temperature. It was then annealed at 50°C for one hour and the internal friction measured at 50°C and at room temperature. The same wire was successively annealed at higher temperatures for one hour and measurements were taken at the annealing temperatures and lower temperatures as before. Such a procedure was followed in order to stabilize the internal friction at the temperature of measurement so that during the measurement which generally takes about half a minute, there is no detectable change in internal friction. This series of measurements .was made up to 450°C. After each annealing a short test piece of the specimen, which had received the same past thermal and mechanical treatments, was taken out for metallographic examination. It is seen from fig. 1 that up to the annealing temperature of 250°C we have the following observations: for any given temperature of measurement, the internal friction is lower the higher the temperature of prior anneal. When the annealing temperature is 290°C or higher, the internal friction at the annealing temperature drops abruptly to a value which is much smaller than that for the previous curve. Metallographic examinations showed that the recrystallization of the specimen was completed after the annealing at 290°C. Fig. 1 shows that, as far as internal friction is concerned, there is no abrupt transition between the processes of recovery and recrystallization. Averbach has also reached the conclusion that recovery may be a process analogous to recrystallization on the basis of X ray extinction measurements in brass." The effect of annealing temperature upon the internal friction at room temperature is shown by curve I of fig. 2. In this figure the internal friction at room temperature was plotted as a function of annealing temperature. It is seen that the internal friction decreases rapidly at first with an increase

Jan 1, 1951

By John K. Kennedy

ThE basic equations describing continuous zone-melting via the zone-void method were reported by Pfann. Using these equations, a theoretical study was undertaken in this laboratory on the effect of the variation of the significant parameters of the zone-void system. These parameters are the zone length, 1, the heater length, h, and the effective distribution coefficient, k. The object of this study was to determine the effect of these parameters on and (where a = Cp/Cf and ß = Cw/Cf, Cp, C,, and Cf being, respectively, the solute concentration in product, waste, and feed) so that, in future application of this technique to the ultrapurification of materials, the effect of 1 and h would be predictable regardless of the value of k. The basic assumptions made by pfannl were, for the purposes of this study, assumed to hold. For k < 1, the steady-state solute distribution in the stripping section and the shift in this distribution brought about by passage of a void is shown in Fig. 7 of Ref. 1. In this section the definition of k and ß precludes the possibility of ß assuming values less than unity when k < 1. In the course of this investigation it was found that computations based on Pfann&apos;s equations gave values of ß less than unity in the region 1 > k > l/h for almost all values of Ls, where Further computations showed that 6 assumes negative values when k > 1 for many values of L,, 1, and h. A check of the derivation of the stripping-section equations showed that an error had been

Jan 1, 1964

By Franz Wever

The importance of the Widmanstätten structure to structure theory in metallography has been recognized by many writers.l It is a structure produced by the precipitation of a, new phase from a solid solution upon cooling as a result of changing solid solubility, and displays a characteristic appearance indicating a crystallographic relationship between the new phase and the original solid solution (Fig. 1). First discovered in 1808 by Alois de Widmanstätten2, the structure has been traced by analogy through many alloy systems. Particularly is this true of the steels. Sorby&apos;s classic work3 on the microstructure of iron and steel was in essence an attempt to explain the origin of this characteristic structure in meteoric iron. He observed in a Ressemer steel and in a cast-steel ingot structures which we now recognize as typical Widmanstatten figures.4 Osmond Observed structures in a steel ingot analog-ous to those found in meteorites. Arnold and Mc William6 obtained (and recognized) a

Jan 1, 1931

By Frederick Prime

AT the last meeting of the Institute, Mr. A. L. Holley read a paper on "Steel," in which he proposes for it a definition so opposed to the one generally received, as to call for some remarks. Until within the last five or six years there has been no dispute on the subject, and it seems worth while to investigate the matter. For not only does a proper tax on all importations depend on a proper appreciation of the term steel, but it is necessary to know whether steel, or wrought-iron, or homogeneous iron are requisite in all processes of manufacture in which malleable iron is employed, on account of cost, strength, etc. Karsteu* says : " Iron may be obtained, either as an unforgeable, unweldable metal, which melts at a high heat, termed cast-iron; or as a ductile, weldable, soft metal, which can only be melted at the * Karsten, Handbuch der Eisenhüttenkunde, 3d ed., vol. i, p. 6. Berlin, 1841.

Jan 1, 1876

By W. J. Rude

LARGEST of the known commercial deposits of pebble phosphate are those found in Polk County, Florida. The phosphate bed, commonly known as the matrix, will consistently average 6 to 9 ft. in depth, and is found under 3 to 60 ft. of over-burden. The phosphate pebbles, white and black in color, varying greatly in grade, are found imbedded in a matrix of sand and clay; and range in size from the fines to pebbles 1 1/2 in. in diameter, although the average coarse size is approximately 1/2 in. in diam¬eter. On some of the washers all material under 14 mesh is lost. High-grade phosphate (75 per cent plus of bone phosphate of lime, CasP2Oa) is generally soft, the pebbles breaking up during the mining operation and in pumping; low-grade phosphate, 67 to 69 B.P.L., is black in color with hard pebbles with no loss encountered in pumping.

Jan 1, 1941