Search Documents

By H. J. Engell, W. Frank, A. Seeger

SWISHER and ~urkdogan' have determined the solubility of oxygen in a iron. They found it to lie between 7 and 10.5 at.-ppm at 881°C. Using earlier work on the permeability of oxygen in bcc iron,' they arrived at the following expression for the diffusion coefficient of oxygen in bcc iron (k = Boltzmann's constant, T = absolute temperature): where The present authors3 have estimated the activation energy QD for the diffusion of oxygen in bcc iron in two different ways from various experimental data.2'4"6 In the first method QD + QS (QS = heat of solution for oxygen in bcc iron in thermodynamic equilibrium with solid FeO) was determined either from data on the reduction of FeO with hydrogen4 or from measurements of the internal oxidation of silicon in a iron.5 Using an estimate of QS from investigations of the oxygen solubility in 6 iron2 (in thermodynamic equilibrium with molten FeO) Q = 0.97 ev or Q~ = 1.06 ev were obtained. From the magnitude of these values it was concluded that oxygen migrates interstitially in bcc iron and that consequently the activation energy QD for diffusion of oxygen has to be identified with the migration energy E~ of the oxygen atoms. Therefore, for a second estimate of QD from the diffusion coefficient of oxygen in 6 iron at 1450" ~,~ we used the theoretical expression:3 (a = length of elementary cube edge, m = mass of interstitially diffusing atom, sM = migration entropy), applicable to diffusion via the octahedral interstices in bcc lattices. Taking sM = 3.8 k (migration entropy of carbon in a iron), one gets Q = 0.90 ev. Hence, in Ref. 3 Q = (0.98 *0.1) ev was proposed as a plausible value for the diffusion energy of oxygen in bcc iron. sM + 9 (9 = solution entropy for oxygen in bcc iron) can be determined from permeability measurements.4 Using the above-mentioned estimate for QS , the following expression for the solubility c (atomic concentration) of oxygen (in thermodynamic equilibrium with solid FeO) in bcc iron was derived: From [4] the solubility of oxygen at 881°C in a iron is calculated to lie between 0.6 and 12 at.-ppm. We see that the solubility determined by Swisher and

Jan 1, 1969

By Walter Stern

The self-potential or spontaneous polarization method is one of the oldest in the field of electrical exploration. When applied in prospecting for ore bodies, it is one of the most rapid and inexpensive means of locating indications of ore bodies at shallow depth. Usually, the procedure is to survey the equipotential lines of the electrical field that is generated by the electrochemical activity of the ore near the ground-water level, and to localize the so-called negative centers or points of greatest negative anomaly. Another field procedure involves the measurement of potential differences along potential profiles, generally laid out at right angles to the assumed strike. Again, in such survey, the basis for establishing the presence of ore is the location of negative potential anomalies. The earlier writers on the subject, notably Schlumbergerl and R. C. Wells,2 did much to clarify the fundamental electrochemical phenomena involved. Interpretation of the field data, however, remained largely qualitative. In 1925, A. Petrovsky3 analyzed the relation between the shape of the potential anomaly curve and size and depth of an Ore body by assuming the subsurface body to be a polarized sphere.' Along similar lines of approach, Edge and Laby5 considered the ore body a dipping sheet with limited extent in the direction of strike, while Poldini6 based the theory on the assumption of a dipping bar. The following study endeavors to enlarge upon these earlier investigations and attempts, on the basis of the potential distribution of a polarized bar, to indicate certain characteristics of the anomaly curve that make possible the determination of depth, size and dip of a subsurface body. The Spontaneous Polarization Field Set Up by an Ore Body If a sulphide ore body is subjected to oxidation varying in degree in its upper and lower parts according to the difference in the concentration of oxygen within the surrounding medium, an electrical potential field is set up. The form and distribution of this field will be investigated herein with special reference to its components on the earth,s surface. Under the simplifying assumption that the ore body may be considered as a dipole with the point sources Q1 and Q2 situated at its upper and lower ends (Fig. I), the potential of the spontaneous polarization at point P is given by the following equation:

Jan 1, 1946

NAME AND OBJECT. SEC. 1. This Institute is incorporated under the Membership Corporation Law of the State of New York ; its corporate name is AMERICAN INSTITUTE OF MINING ENGINEERS; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II. MEMBERS. SEC. 1. The membership of the Institute shall comprise four classes, namely (1) Members ; (2) Honorary Members , (3) Associates , and (4) Honorary Associates Only Members and Associates residing within the United States of America, Republic of Mexico and Dominion of Canada shall be entitled to vote at the meetings of the Institute. SEC. 2 All Members, Honorary Members, Associates and Honorary Associates of the American Institute of Mining Engineers as the same existed on the day of the incorporation of this Institute, are Members, Honorary Members, Associates and Honorary Associates, respectively, of this Corporation SEC. 3. The following classes of persons shall be eligible for membership in the Institute, namely, as Members and Honorary Members, all professional mining engineers, geologists, metallurgists or chemists, and all persons practically engaged in mining, metallurgy or metallurgical engineering ; as Associates and Honorary Associates, all persons desirous of being connected with the Institute who, in the opinion of the Council, are suitable. SEC 4. Every candidate for election as a Member or Associate of the Institute must be proposed for election by at least three Members or Associates; must be approved by the Committee on Membership, as prescribed in the By-Laws ; and .must be elected by the Council. Not less than three-fourths of the votes cast shall be necessary to an election Every person so elected shall become a Member or Associate, as the case may be, upon payment of his first dues as herein-after prescribed Each candidate for Honorary Member or Honorary Associate, must be recommended by at least ten Members or Associates ; must be approved by the Council ; and must be elected by ballot at a meeting of the Board of Directors by the unanimous vote of all the Directors present ; provided, however, that the number of Honorary Members and Honorary Associates shall not at any time exceed twenty SEC. 5. If any person elected a Member or Associate does not, within sixty days after notice of his election, accept the same and pay his initiation fee and dues for the current year, his election may be cancelled at the discretion of the Council.

Jan 1, 1917

NAME AND OBJECT. SEC. 1. This Institute is incorporated under the Membership Corporation Law of the State of New York ; its corporate name is AMERICAN INSTITUTE OF MINING ENGINEERS; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II. MEMBERS. SEC. 1. The membership of the Institute shall comprise four classes, namely (1) Members ; (2) Honorary Members , (3) Associates , and (4) Honorary Associates Only Members and Associates residing within the United States of America, Republic of Mexico and Dominion of Canada shall be entitled to vote at the meetings of the Institute. SEC. 2 All Members, Honorary Members, Associates and Honorary Associates of the American Institute of Mining Engineers as the same existed on the day of the incorporation of this Institute, are Members, Honorary Members, Associates and Honorary Associates, respectively, of this Corporation SEC. 3. The following classes of persons shall be eligible for membership in the Institute, namely, as Members and Honorary Members, all professional mining engineers, geologists, metallurgists or chemists, and all persons practically engaged in mining, metallurgy or metallurgical engineering ; as Associates and Honorary Associates, all persons desirous of being connected with the Institute who, in the opinion of the Council, are suitable. SEC 4. Every candidate for election as a Member or Associate of the Institute must be proposed for election by at least three Members or Associates; must be approved by the Committee on Membership, as prescribed in the By-Laws ; and .must be elected by the Council. Not less than three-fourths of the votes cast shall be necessary to an election Every person so elected shall become a Member or Associate, as the case may be, upon payment of his first dues as herein-after prescribed Each candidate for Honorary Member or Honorary Associate, must be recommended by at least ten Members or Associates ; must be approved by the Council ; and must be elected by ballot at a meeting of the Board of Directors by the unanimous vote of all the Directors present ; provided, however, that the number of Honorary Members and Honorary Associates shall not at any time exceed twenty SEC. 5. If any person elected a Member or Associate does not, within sixty days after notice of his election, accept the same and pay his initiation fee and dues for the current year, his election may be cancelled at the discretion of the Council.

Jan 1, 1910

By J. T. Norton, A. L. Mowry

S. J. SINDEBAND*—(1) Discussing the properties of the powders used, Mr. Rostoker mentioned a silicon powder as being between 150 and 325 mesh. We always had much difficulty in measuring particle size of silicon powder by screen analysis, because of its tendency to agglomerate. I would be interested in the method used to measure these particle sizes. (2) Mr. Rostoker maintains that the measurement of magnetic properties is more accurate in determining complete homogenization of an alloy, than is the X ray diffraction technique. I wonder whether this is really true. Even when diffusion is complete, magnetic properties will change during continuation of the heat treatment, due to change in density and pore shapes, as has been demonstrated by Mr. Rostoker himself. Which effect is faster, the diffusion of the alloy components or the attainment of final density, will, in my opinion, depend very much on initial material and sintering conditions used. For magnetic applications, of course, the magnetic measurements are most suited for determining the point at which equilibrium conditions are reached. (3) I was glad to see that Mr. Rostoker had used sample sizes which are similar to those I had used previously, and I believe that ring samples of about 2 in. od will become more or less standard samples for the determination of magnetic properties of powder metallurgy products. I should like to ask how the density was changed for the samples on which the effect of porosity was investi- gated, and, further, why the sintering temperature used for this series of experiments was so low. It is somewhat surprising that a 24-hr treatment at 850°C acts so much more to spheroidize the pores than a treatment for 1 hr at 1100°C. But the effect seems to be indisputable. I have made an investigation of the influence of sintering temperature for longer times on the maximum permeabilities of iron powder compacts which was presented at the International Powder Metallurgy Conference in Graz, in 1948, and I hope that these results will be published here within a short time. The results of this investigation are confirmed by Mr. Rostoker's findings that the change of time from 1 to 24 hr changes the permeability behavior considerably in the direction as indicated by Polder and Van Santen for spheroidiza-tion of pores. I do not quite understand Mr. Rostoker's explanation of the influ-

Jan 1, 1950

By S. F. Reiter, R. W. Guard, J. H. Keeler

DURING the last several years the authors have been conducting tests on a tensile machine that autographically records load-elongation data. In certain tests at elevated temperatures on face-centered cubic, hexagonal close-packed, and body-centered cubic materials (binary alloys of nickel, zirconium, and iron), the load-elongation curve as shown in Fig. 1 reaches a maximum load (Pmax,) at relatively small amounts of strain and a large amount of elongation occurs subsequently with a continuously decreasing load, until finally localized necking and fracture take place. This early maximum load behavior has been found without the accompanying evidence of localized necking as has been assumed by some, or of evidence of cracking as observed by others.' This behavior has also been observed by Nadai and Manjoinez whose results are in good agreement with ours. The prior strain, strain rate, test temperature, and crystal structure affect the observations. The influence of prior strain was observed in tests on unalloyed zirconium at 300°C in which specimens containing large amounts of prior strain (cold work) exhibited the type of curve shown in Fig. 1. No localized necking was observed after strain as much as that of point B. Annealed and recrystallized specimens of the same material showed a load-elongation curve with maximum load occurring after considerable strain hardening and at the beginning of localized necking. Interrupted tests (Fig. 2) show no loss in strength because of recovery or recrys-tallization during an interval at temperature without load. Recovery under stress such as found by Wood and Suiter3 in aluminum is now being investigated as one possible explanation. The strain rate is a contributing variable as shown in Fig. 3, a test on high purity nickel. Here the strain rate was decreased by a factor of ten during a test in which the maximum load was reached at a small strain. The slope of the true stress-true strain curve was positive with the more rapid strain rate and negative with the slower strain rate. In many binary ferrites an added effect of temperature has been observed. Fig. 4 shows the load-elongation plots for a binary ferritic alloy containing 2 pct Mo. The slope of the small portion of the stress-strain curve obtained at a strain rate of 0.01 mhr1 changes sign from negative to positive on going

Jan 1, 1955

By John Henry Harden

THIS shaft, located in the northern anthracite coal-field about 2300 feet southwest from the court-house at Wilkes-Barre, in the County of Luzerne, Pa., is the property of the Lehigh & Wilkes¬Barre Coal Company. The sinking and cribbing to the solid rock (see isometrical view on Plate IX) was conducted by Mr. W. W. Kenrick. Dimensions of the earthwork to the foundation of the cribbing, 51' 1/2" long, 17' 4" wide, 31' deep. Total amount of excavation in cubic yards, 998.5. Dimensions within the permanent cribbing, 45' 4" long, 11' 16" wide, 31' deep, divided into six parts by buttons 8" x 12", each division, 7' x 11’ 16". Permanent cribbing 12" x 12"; temporary cribbing 8" x 10"; backing, 3" thick ; clay puddle to ex¬clude surface water, 12" thick; conductors, 8" x 5"; lining, 1" thick from top to bottom of the shaft. In the latter part of the year 1871, Mr. H. Murray & Son contracted with the company for the continuation of the work at the rate of four hundred dollars per yard in depth, to a point 100 feet below the Hillman seam of coal ; for the succeeding 100 feet the price to be increased twenty-five dollars per yard, and so on until the bottom rock of the Baltimore seam of coal was found. The size of the shaft within the cribbing timbers is 45 feet 4 inches by 11 feet 6 inches, having six divisions of equal dimensions, 7 feet by 11 feet 6 inches, giving room for what is known as the" standard diamond" car, whose capacity when level full is 100 cubic feet, but when loaded by the miner 4 inches above the top contains 112 cubic feet.* Two divisions of this shaft are intended for hoisting coal from the Hillman seam, two from the Baltimore seam, one for ventilation, and one for pumps. The works were planned for two pairs of direct-acting, high-pres¬sure engines, twenty-four boilers, and for an estimated output of 2500 tons of coal per day from the two seams. * Size of the "standard diamond" car, 8' 10” x 4' 3" x 2’ 8” = 100.1.4; loaded 4 inches above the top, 8' 10” x 4’ 3” x 3’ “0"= 112.7.6.

Jan 1, 1877

By S. Shapiro, G. Krauss

We will reply to Dr. Pitsch's discussion by 1) presenting in greater detail the single surface trace analysis which we performed on the reversed austenite plates in a single parent plate of martensite of known orientation, 2) relating the results of our analysis to the conclusions which Dr. Pitsch makes on the basis of our data, and 3) examining the validity of our selection of twenty-nine individual traces from the over 200 austenite plates which were observed in a surface of this single martensite plate. Fig. 7 shows a standard (001) projection of the martensite plate from which the austenite-martensite interface traces were taken. The traces are plotted on the projection as the small solid circles, and the great circles corresponding to the loci of plane normals which could contain each trace or could intersect the surface plane along the measured directions are also plotted. It can be seen that these great circles intersect at a point which corresponds to the normal of the surface plane on which the traces were observed. Also rate which occurred only at particularly low heating rates, see Figs. 1 and 3 in the paper.2 Since in this case the interpretation of Jana and Wayman is plausible and since we have no alternative to this interpretation, we would like to state only that the existence of a diffusion-controlled reversal at low temperatures seems to be not yet proved beyond any doubt. The author wishes to thank Professor G. Krauss for making available his manuscript prior to publication. It is also a pleasure to acknowledge the lively written discussions, which the author has had with Professors G. Krauss and C. M. Wayman prior to this communication. The financial support of the Deutsche For-schungsgemeinschaft for the work on which this communication is based is also gratefully acknowledged. plotted within small dotted circles which represent a i3 deg scatter in each of the twenty-four unit stereo-graphic triangles are our A and B poles7 and the pole P determined by Kessler and itsch.' The data presented in Fig. 7 permit a direct association of the measured traces and the various proposed habit plane poles for the reversed austenite plates in the martensite crystal. If the sample measurements do in fact

Jan 1, 1969

By Oliver B. Hopkins

Peru produced approximately 17,466,620 bbl., of oil during 1937, or slightly less than the record high of 17,593,700 bbl. established during 1936. As in 1936, the entire output of the country was derived from the La Brea-Parinas, Lobitos-Restin and Zorritos fields in the northwestern part of the country. Outside of the proven areas, drilling was 'continued by the Peruvian Government in the northern province of Tumbes on the reserved zone at Zorritos. Drilling was carried out on three locations, two of which are understood to have been abandoned during the year. In southern Peru, further attention was given by Government engineers to the Pusi and Saman districts and plans are being worked out for the commencement of drilling operations in the near future in the vicinity of Pirin. Activities in the montaiia region in eastern Peru were continued by the Compafiia Petrolera El Ganso Azul. This company acquired the interest of the Selden Breck Co., and holds some 90,000 acres along the Pachitea River a few miles above its confluence with the Ucayali. During the year, the preparation of a landing place, the cutting of a 12-km. (71/2-mile) road from the river to the drill site, and the construction of a camp were undertaken. Equipment for drilling on this company's concessions has already arrived in South America. La Brea-Parinas Estate.—Production of crude oil on the La Brea-Parinas Estate of the International Petroleum Company Limited amounted to 14,722,754 bbl. during 1937, a decrease of 403,736 bbl. from the all-time high reached during 1936. The total production from 1890 to Dec. 31,1937, was 178,390,767 bbl. During 1937, a total of 141,653 ft. was drilled, 129,516 ft. in new wells and 12,137 in deepening existing wells. In all, 57 wells were completed, 47 of which produced oil, 2 were gas wells and 8 dry. holes. Twenty-nine wells were cleaned out or deepened during the year. The average depth of new wells completed during 1937 was 2367 ft. compared with 1984 ft. for the new wells completed during 1936. There was an increased use of rotary tools during the year and this method is now used to a greater extent than the cable-tool method, which formerly predominated. Of the 57 wells completed during the year, 31 were

Jan 1, 1938

By B. E. Lindsly

The withdrawal of gas and/or oil in appreciable quantity from a natural oil reservoir causes the pressure within the reservoir to diminish, and if the oil is completely saturated with gas, this dissolved gas begins to evolve from solution. The liberation of gas from solution in oil causes the oil to change in several ways, the principal changes being: (1) reduction in volume or "shrinkage"; (2) increase in specific gravity (decrease in degrees A.P.I.); (3) decrease of energy in the oil; (4) increased viscosity; (5) increased surface tension. As the writer's investigations have been concerned more with the first three items than with changes in viscosity and surface tension the following discussion relates particularly to the volumetric shrinkage of the oil, to the increased specific gravity, and to the decreased energy in the oil, each caused by the liberalion of dissolved gas. One of the most surprising facts that have developed in the study of high-pressure well-head and "bottom-hole" samples is the great reduction in volume that occurs in some oils when the naturally dissolved gas is liberated. High-pressure samples taken from well heads in the Oklahoma City, Kettleman Hills and Ventura, Calif., fields decreased in volume from 11.2 to 40.5 per cent when the dissolved gas was liberated in reducing the pressure on the sample to atmospheric. The amount of shrinkage an oil undergoes when gas is liberated depends upon the quantity of gas liberated and also upon its composition. A given volume of the heavier gases, propane and butane for example, will occupy more space in the oil than an equal volume of methane. The reason for this probably is that the molecules of the heavier gases are larger than those of the lighter gases. When gases are not in solution, and particularly when they are at low pressures, the distance between the gas molecules is so much greater than the dimensions of the molecules themselves that the mere size of the molecules has little effect upon the space occupied by the gas, Avogadro's hypothesis, which in effect states that all gases under the same conditions have the same number of molecules per unit volume, relates to this phenomenon. The fact that the heavier gases occupy more space than the lighter gases in the oil, and

Jan 1, 1934

By William P. Mason

FoR reasons unnecessary to enter into here, I was called upon to contradict the statement that " closed metallic vessels, partly filled with water and heated, do not become shattered by violent explosion, but simply rupture by over-pressure;" and the following experimental results were obtained in support of my position : A piece of drawn brass tubing (telescope-tubing) 1 1/2 inches in diameter and 15 inches long was closed at both ends by screwing on heavy caps of bronze. Before closing the second end the vessel was half filled with river water, the cap was then screwed on, and the closed vessel was supported upon two iron anvils, and heated in the interval between the supports by a large Bunsen lamp. The resulting explosion (which was doe to over-pressure only and not to any more occult cause) was exceedingly violent. No small damage was done to the room in which the experiment was undertaken; and the noise was like that of a cannon. Those of the pieces which could be recovered are shown in Fig. 1. Upon examining the wreck, it was noticed that one of the heavy bronze end-caps had preserved its circular section and still contained that portion of the barrel of the tube which had been screwed into it, while the other end-cap contained no portion of the tube, and was moreover sprung into a shape more or less elliptical, as if from excessive lateral strain. It was also observed that the large pieces of the shattered boiler predominated towards the end which had been closed by the un-sprung end-cap. The reasonable explanation, in view of the facts, was, that over-pressure had caused the boiler to yield through the screw-threads at A B, Fig. 2, and the righthand end-cap had blown off, thus leaving the boiler half filled with water, greatly super-heated for the new (atmospheric) pressure to which it was suddenly reduced; that this water had consequently sprung instantly into steam with dynamite effect, shattering the tube and springing the remaining end-cap. The large pieces would be expected at the open end of the boiler, as at that point the "tamping "would have been that of the atmosphere only. This explanation assumes a rupture to have been caused by gradually increased pres-

Jan 1, 1893

Although the 71 Minerals operation is now closed down and the operating data presented is almost five years old, it is well worth describing since it was the first heap leaching operation conducted on a primarily silver ore. Tombstone was discovered in 1877 by Ed Schieffelen; and it became one of the most famous mining towns in the West through the stories connected with Wyatt Earp, Doc Holliday, and the Clanton brothers. Like many silver deposits .in the western United States, the Tombstone ores were relatively shallow. Several million ounces of silver were recovered in the relatively few years the camp was active; but mining virtually ceased by the early 1900s and was only continued in a small way until the 19409, a history similar to that of Tuscarora. The 71 Minerals operation was started in May 1975 and continued until late 1978 within the city limits of Tombstone on waste dumps; one was the' Lucky Cuss, Schieffelen's discovery, which had accumulated from the old underground operations. This waste material was mostly less than 50 mm (2 in.) in size, although there was some larger lumps. The grade was about 34 g Ag and 0.5 g Au per mt (1.0 oz Ag and 0.015 oz Au per st). The Tombstone dumps contained approximately 1,000,000 tons. The dumps and patented claims were held by a single owner, Tombstone Development Company, thus sufficient leaching material could be acquired from one source rather than dealing with a number of individuals, as is usual in putting together leaching ventures in old mining camps. 71 Minerals Ltd. was formed and a lease of the properties obtained. A site was selected close to the major mine dumps not far from down- town Tombstone. Pads approximately 90 m (300 ft) wide and 180 m (600 ft) long with an 8-degree slope were prepared using compacted old mill tailings as a base sealant on the pads. Mining was done at a rate of about 2,000 tons per day with a dozer, two scrapers, a front-end loader, and 30 ton trucks. The ore was dumped by the scrapers as it came from the dumps with no screening or crushing in 460 mm (18 in. ) layers and trimmed with the loader. Based on bulk sampling and laboratory testing, the majority of thegold and silver values were recovered within 30 days of leaching.

Jan 1, 1981

By V. Balasubarmanian, Rajendra Kumar

ISOTHERMAL formation of martensite in a copper-aluminum-nickel alloy was previously reported by Hull and Garwood.' In the present work an attempt has been made to investigate some of the character- istics of the formation of isothermal martensite in binary copper-aluminum alloys containing 14.00 and 14.50 pct Al, respectively. Chill-cast alloys were prepared from OFHC copper and aluminum of greater than 99.5 pct purity. They were homogenized for 24 hr at 950° C. Polished samples were soaked at 1000°C and quenched in water to retain the p phase untransformed; martensite did not form during the quench. The surface was then repolished for isothermal microscopic studies at room temperature. The salient features of the martensitic transformation in copper-aluminum alloys observed in this investigation are: a) The transformation progresses (i) by nuclea-tion at new sites and (ii) by simultaneous slow isothermal growth of existing martensite plates. Slow isothermal growth of martensite has previously been observed by Holden2 in an uranium-chromium alloy and by Hull and Garwood in copper-aluminum-nickel alloy. b) Martensite plates nucleate preferentially at the pin holes formed during the casting of the specimen, Fig. 1. c) Some of the martensite plates pass right through other plates lying in their path, Fig. 1. d) Martensite plates cross grain boundaries without any change in the direction of growth. e) An irregular network of markings, Fig. 2, appears simultaneously with the formation of martensite. It was less prominent in the case of 14.5 pct alloy. The markings may arise due to spontaneous deformation under the lattice strains of the martensitic transformation. Crossing of martensite plates was first observed by Kulin and cohen3 when a high-nickel steel was cooled to 77°K. They suggested that the rapidly advancing plates atquire considerable kinetic energy and strike the obstructing plate with a momentum so as to nucleate the process on the other side of the plate. This, however, fails to explain the present observation where the slow isothermally growing martensite plates cross each other. Such plates would not possess large momentum to bodily displace the obstructing plate. Fig. 1 shows the martensite plates crossing each other without body displacements. This should be contrasted with Fig. 3 of Kulin and Cohen's paper where crossing of plates is accompanied by shearing or body displacements of the plates. The present observations can, how-

Jan 1, 1961

NAME AND OBJECT. SEC. 1. This Institute is incorporated under the Membership Corporation Law of the State of New York ; its corporate name is AMERICAN INSTITUTE OF MINING ENGINEERS; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II. MEMBERS. SEC. 1. The membership of the Institute shall comprise four classes, namely (1) Members ; (2) Honorary Members , (3) Associates , and (4) Honorary Associates Only Members and Associates residing within the United States of America, Republic of Mexico and Dominion of Canada shall be entitled to vote at the meetings of the Institute. SEC. 2 All Members, Honorary Members, Associates and Honorary Associates of the American Institute of Mining Engineers as the same existed on the day of the incorporation of this Institute, are Members, Honorary Members, Associates and Honorary Associates, respectively, of this Corporation SEC. 3. The following classes of persons shall be eligible for membership in the Institute, namely, as Members and Honorary Members, all professional mining engineers, geologists, metallurgists or chemists, and all persons practically engaged in mining, metallurgy or metallurgical engineering ; as Associates and Honorary Associates, all persons desirous of being connected with the Institute who, in the opinion of the Council, are suitable. SEC 4. Every candidate for election as a Member or Associate of the Institute must be proposed for election by at least three Members or Associates; must be approved by the Committee on Membership, as prescribed in the By-Laws ; and .must be elected by the Council. Not less than three-fourths of the votes cast shall be necessary to an election Every person so elected shall become a Member or Associate, as the case may be, upon payment of his first dues as herein-after prescribed Each candidate for Honorary Member or Honorary Associate, must be recommended by at least ten Members or Associates ; must be approved by the Council ; and must be elected by ballot at a meeting of the Board of Directors by the unanimous vote of all the Directors present ; provided, however, that the number of Honorary Members and Honorary Associates shall not at any time exceed twenty SEC. 5. If any person elected a Member or Associate does not, within sixty days after notice of his election, accept the same and pay his initiation fee and dues for the current year, his election may be cancelled at the discretion of the Council.

Jan 1, 1910

By J. R. Cahoon, W. V. Youdelis

In a previous communication by one of us,1 a theory of inverse segregation was presented by which the maximum segregation and segregation distribution throughout a unidirectionally solidified, binary-alloy ingot could be calculated. The theory, which is based on the mechanism of volume contraction and interdendritic flow, quantitatively accounts for the observed maximum segregation in the A1 (rich)-CU' and Al-Zn2 alloy systems, and for the segregation distribution along the ingot lengths for the A1-Cu system.''4 One of the drawbacks to a more extensive use of the segregation equations is their complexity, particularly for the calculation of the segregation distribution throughout the length of the ingot, involving long tedious numerical calculations to obtain the segregation. Computer pro- grams, written in Fortran II for use on an IBM 1620 computer, have been developed by the authors (and are available from them), providing quick and accurate methods for the determination of the theoretical maximum segregation in any binary-alloy system, and also for the segregation distribution in any unidirectionally solidified binary-alloy ingot. The segregation distribution is controlled by the lengths of the various solidification zones'74 which are in turn controlled by the cooling rate, and are determined from temperature-distribution curves obtained during solidification. The theoretical segregation distributions shown in Fig. 1 illustrate the effect of the zone lengths on the distribution Curve 1, indicative of a slowly cooled ingot, represents an ingot having long solidification zones, while Curve 2, indicative of a rapidly cooled ingot, represents an ingot having relatively short zones. Although these distributions are calculated for an A1-10 pct Cu ingot, the shape of the distribution would be similar for any binary-alloy ingot. These curves show clearly why early workers obtained results which indicated that the maximum (chill-face) segregation approached zero at very fast cooling rates.3 Actually, the maximum segregation is independent of cooling rate,' but even at short distances from the chill face the amount of segregation drops considerably, particularly in a rapidly cooled ingot, making it very difficult to establish the amount of segregation occurring at the chill-face. The authors would like to thank Dr. J. A. Goldak for his assistance in the preparation of the programs. The financial assistance of the Steel Co. of Canada and of the National Research Council of Canada in the form of Scholarships to one of us (J. R. Cahoon) is gratefully acknowledged.

Jan 1, 1964

By Gerald Edmunds, R. K. Waring, E. A. Anderson

Brass is liable to failure under the combined influence of stress, certain corrosion media, and time, a phenomenon commonly termed season cracking or stress-corrosion cracking. The consequences of this are serious in applications of brass generally, including the important field of cartridge cases. Cartridge cases (70 Cu: 30 Zn) that fail from this cause may allow the escape of gas from the gun breech, a hazard to the shooter, and may not eject, thus temporarily putting the gun out of action. In loaded cartridge cases, the stress present is partly residual from the, drawing and necking operations and partly applied by the insertion of the projectile. Ammonia, present as a decomposition product of smokeless powder, air and moisture constitute corrosive media. The prevalence of season cracking has been reduced considerably, but not eliminated, during the past quarter of a century by low-temperature annealing to relieve stresses residual from fabrication, a method suggested by Diegel 38 yr. ago(I).2

Jan 1, 1945

By William C. Alden

A great landslide occurred on June 23, 1925, in the valley of Gros Ventre River, about 35 miles south of Yellowstone National Park (Fig. 1). The relations of the north-easterly dipping rock formations of the slide scarp and of the dam formed by the slide are shown in the diagrammatic cross-section of the valley (Fig. 2). This generalized section is based on unpublished maps and notes by Eliot Rlackwelder, in the files of the IT. S. Geological Survey. Heavy rains and melting snow in the Gros Ventre Mountains had saturated clay layers in the Carboniferous strata, which dip toward the valley at angles of 18" to 21°, consequently an enormous mass of rock at the end of the north spur of Sheep Mountain became loosened and, on the afternoon of June 23, slid suddenly down into the valley. Within a few minutes this mass of debris—estimated as 50,000,000 cu. yd.—carrying

Jan 1, 1928

By J. T. Burwell

As is well known, the alloys of iron containing 18 ± per cent chromium, 8 ± per cent nickel and less than 1.2 per cent carbon exhibit the same allotropic modifications as iron. The face-centered cubic or gamma phase is stable at high temperatures and the body-centered cubic or alpha ferrite is presumably stable at room temperature. The transformation from the gamma phase to the alpha phase in alloys of the above composi-tion (18-8 or stainless steel) is sluggish; even moderately rapid cooling permits the retention of the gamma phase. Cold-work, however, causes the transformation from gamma to alpha to occur at room temperatures. It is difficult, nevertheless, to induce complete transformation regardless of the method of cold-working. Since metallographic polishing is very effective in transforming the surface austenite to ferrite, as indicated by the magnetic studies of Buehl and Wulff, 1 it was decided to investigate the phenomenon by electron diffraction methods.

Jan 1, 1939

Although copper production established a new record, lead and zinc registered gains, and iron production held steady, the mixed trend in metallic and nonmetallic mining and generally lower prices in 1961 resulted in a net decline in the total value of domestic mineral production. According to preliminary estimates from the U.S. Bureau of Mines, the value of metals produced in this country during the year was approximately $1.9 billion, a decrease of $117 million from 1960; the value of nonmetallics was about $3.7 billion, a $14 million decrease. The following report of mining and mineral developments during 1961 is based on USBM and industry sources. Aluminum Output Dips from 1960 Record Government reports indicate that the domestic primary aluminum industry produced approximately 1,880,000 tons, equivalent to 77% of this nation's capacity. This production is about 6% below the 1960 record output of 2,014,498 tons. Shipments of primary metal ingot slightly exceeded the quantity produced.

Jan 2, 1962

By D. W. Smith

THE beta solid solution phases of the systems copper-zinc, copper-aluminum, copper-tin and silver-zinc are structurally analogous.1 R. F. Mehl and 0. T. Marzke2 have shown that the a phase upon segregating from the 0 phase in the system copper-zinc takes the form of needles lying parallel to a [111.] direction or some similar direction, such as [556], of the parent solid solution, and that the a phase upon segregating from the ß phase in the system copper-aluminum also takes the form of needles. By analogy they assume that in this case also the segregate needles lie parallel to the [111] or [556] direction in the ß lattice. The purpose of this investigation is to determine whether the structures resulting from segregation of the a phases from the respective 0 phases of the systems copper-tin and silver-zinc are analogous to those obtained by Mehl and Marzke in the systems copper-zinc and copper-aluminum.

Jan 1, 1932