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By Charles Wert

THE diffusion and precipitation of carbon and nitrogen in a iron have previously been investigated using the internal friction as a measuring tool.' Most of this work has been done on rather pure iron; no effect was observed which would indicate that either of these phenomena is affected by the rather small amounts of impurity found in these samples of iron. Fastz observed, however, that both the diffusion rate and the aging properties of nitrogen in iron were sensibly changed by the addition of Vz pet Mn. The diffusion rate at a given temperature is reduced and the nucleation of nitrides is apparently changed somewhat. He observed no such changes for carbon in this alloy. Later Dijkstra and Sladek" extended these observations on nitrogen to other alloys of iron. They found that metals other than manganese also influence the behavior of nitrogen in iron; chromium, molybdenum and especially vanadium affect the diffusion and precipitation of nitrogen even more than manganese does. Their results have been verified in all essential details by this author, who finds in addition that small additions of nickel have about the same effect on the diffusion of nitrogen as the same amount of manganese. The present work was undertaken to study the effect on carbon in iron of these alloying elements. The alloys used had two sources. The material used as a "standard" (designated Fe in this paper) in the measurements was some iron supplied by J. K. Stanley, of Westinghouse Electric Corp., who reported 0.01 pct 0, as the only major impurity. He also made up an alloy of 0.26 pct Ni and one of 0.9 pct Mo using this same iron as a base. They were supplied by him in 2 lb billets, which were sawed into rods and cold formed into 0.030 in. wires for measurement. The alloys of chromium, manganese, and vanadium were prepared by the metallurgy section of the Institute for the Study of Metals, University of Chicago, by adding these metals in turn to vacuum melts of National Research Corp. iron. The small castings prepared in this way were also cold formed into 0.030 in. wires. After these wires had been prepared they were decarburized for 30 min at 730°C in wet Hz. After this treatment, no trace of carbon (as measured by internal friction) could be found. All specimens were then carburized for about 15 min at 710°C and water quenched. By this treatment the internal friction at 40°C was raised to a Q-' ~ 0.015. The diffusion of carbon in these alloys was studied by observing the shape and position of the internal friction peak at 0.9 cycles per sec. These measurements were made using a torsional pendulum in a manner described earlier.' The data are plotted in Fig. 1. It is seen that there is no apparent difference in internal friction between the various alloys. This is in marked distinction to the broadening and shift-

Jan 1, 1953

By Richard J. Borg

The vapor pressure of Cd in equilibrium with CdSb in the presence of excess Sb has been measured using the Knudsen effusion method over the temperature range 276° to 379°C. The free energy of formation of CdSb is given by AF° = -1.58 + 1.53 x l0-4 T, kcal per mole. The enthalpy and entropy are obtained from the temperature coefficient of the .free energy. CADMIUM and antimony have almost imperceptible mutual solid solubility but form a single stable intermediate phase, CdSb. This phase, according to Han-sen,l extends from about 49.5 at. pct to 50 at. pct Cd at 300°C and has the orthorhombic structure. The free energy of formation of CdSb can be calculated from the vapor pressure of Cd for compositions which contain less than 49 at. pct Cd. The appropriate reaction and formulae are given by Eqs. [I] and [2]- CdSb(s, ~ Cd(g)-, +Sb(s) [1] Since Sb is in its standard state, Af - N,,AF'-,, = NcdRT In a,, = NcdRT InP/PO [2] In Eq. [2], P, is the vapor pressure of Cd in equilibrium with the alloy, and Po is the vapor pressure in equilibrium with pure solid Cd. It is implicit in this calculation that the free energy only slightly changes within the narrow limits of the single phase field. Thus, the value obtained from the antimony-rich boundary is truly representative of the stoi-chiometric compound. The results reported herein are obtained from a mixture near the eutectic composition, i.e. 59 at. pct Sb. Only two previous investigations" of the free energy of formation of CdSb have been made. Both relied upon the electromotive force method, and measurements were made over relatively narrow temperature ranges which strongly influences the reliability of the values of AH and aS. EXPERIMENTAL The eutectic composition is prepared by fusing reagent grade Cd and Sb by induction heating in vacuo with the starting materials held in a graphite crucible having a threaded lid. The material obtained from the initial melt is pulverized, sealed under high vacuum in a pyrex capsule, and annealed at 420°C for two weeks. X-ray analysis"gives the following lattize parameters: a = 6.436A, b = 8.230& and c = 8.498A using Cu Ka radiation with A = 1.54056. These values are in fair agreement with the result? previously reported by Al~in:4 i.e. a = 6.471A, b = 8.253A, and c = 8.526A. Vapor pressures are measured using an apparatus which has been described elsewhere,= however, with a single important modification. Knudsen effusion cells are made of pyrex with knife-edged orifices made by grinding the convex surface of the lid on #600 emery paper. Photographs taken at known magnifications using a Leitz metallograph enable the determination of the orifice area. Numerous calibration measurements of the vapor pressure of pure Cd give close agreement with values previously reported5,= thus indicating that no significant error can be ascribed to the substitution of glass cells for metal cells used in previous work. Because the vapor pressure of Cd is reliably established and because it is difficult to obtain Clausing factors for the glass cells, the final values used for the orifice areas are calculated from the calibration measurements of the vapor pressure of pure Cd. Effusion runs are started in an atmosphere of purified helium which is quickly evacuated as soon as the cell attains thermal equilibrium. Less than one minute is necessary to obtain high vacuum after evacuation begins, and the temperature seldom varies by more than 0.5oC from the value obtained prior to pumping out the helium. RESULTS The results of this investigation along with other pertinent data are tabulated in Table I. Fig. 2 is the familiar graph of log P against T-10 K. At least mean squares analysis of the data presented in Table I yields the following equation: log1DJP = 8.790 - 6472 x T"1 [3] The deviations of the individual measurements from the values calculated with Eq. 131 are given in column six of Table I; the average deviation is 4.0% of the calculated value. Although the partial molal properties change significantly with composition within the single phase region, the integral thermodynamic value should remain relatively constant. Hence the results of the following calculations, which use the data obtained for the eutectic composition, are probably representative of the equi-atomic compound. Eq. [4] describes the vapor pressure of pure Cd as a function of temperature and may be combined with Eq. [3] to

Jan 1, 1962

By Eugene Stephenson

IN most instances the fluids produced from underground reservoirs have been described as they appear at the surface, and usually it has not been necessary to distinguish between surface and reservoir phases. More recently it has become imperative to recognize the fact that changes in phase may occur between the reservoir and the receiving unit. The simple terminology of "wet" and "dry" gases and "crude petro-leum oil" served our needs fairly well in the shallow, low-temperature and low-pressure fields. It has been left to the legislatures, regulatory com-missions, and courts to decide whether a field is or was a gas field, an oil field, or both. This they have done by direct definition and also by implication. For example, in Texas:1 (d) The term "gas well" is any well (a) which produces natural gas not associated or blended with crude petroleum oil at the time of production, or (b) which produces more than one hundred thousand (100,000) cubic feet of natural, gas to each barrel of crude petroleum oil from the same producing horizon, or (c) which produces natural gas from a formation or producing horizon productive of gas only encountered in a well bore through which crude petroleum oil is also produced through the inside of another string of casing. (e) The term "oil well" is any well which produces one (1) barrel or more of crude petroleum oil to each one hundred thousand (100,000) cubic feet of natural gas.

Jan 1, 1938

By W. L. Austin

AT the Steptoe metallurgical plant, where ore of the Nevada Consolidated Copper Co. is beneficiated, a small copper-leaching annex has been in operation treating flue dust from roasting-furnace dust chambers, together with a siliceous oxidized ore. This leaching plant was designed to obviate smelting low-grade siliceous flue dust, which interfered with the operation of the reverberatories by forming a blanket on the charge The major portion of the copper content of the flue dust accumulating in the upper chambers of the. roaster flue, and at the stack, is water soluble, and also contains much free sulphuric acid and soluble sulphate It was found that sufficient acid could be obtained by mixing this material with water to provide a lixiviant for leaching the siliceous copper o mentioned. This was the sole source of the lixiviant used in the operatic to be described. An analysis of the flue dust showed it to be composed as follows: Per Cent. Copper 3.00 SiO2 23.41 Fe : 4.08 CaO + MgO : 2:72 Al203 6.07 Free H2SO4 19.94 S03 combined as sulphate 25.10 H2O combined With the sulphates 10.67 0 2.50 Total 97.49 Copper soluble in dilute H2SO4 2,56

Jan 7, 1914

By J. G. Balkestein, J. W. R. Baerts

During an attempt to develop a method for accurate, rapid, continuous analysis of ash content of wal, the Dutch State Mines Laboratory found that the absorption coefficient for X-rays was related to ash content. This relationship was utilized in the development of an apparatus called CendreX, used to measure the absorption and in turn the ash content. The principle, procedure, accuracy, and applications of the CendreX automatic determination of ash in coal are discussed in detail. Until recent years coal preparation research was concentrated on the possibilities and efficiency of preparation equipment. Ever increasing demands for quality in coal, however, have caused researchers to become concerned with quality control. One of the characteristics strongly influencing quality (calorific value) and, consequently, the price of coal is ash content. Both customer and producer require that the ash content be controlled. To make this possible it is necessary for the producer to collect samples from the coal stream in the washery and to determine their ash content. On the strength of the results obtained the production process can then be adjusted, if required. Until recently incineration was the only method for determining ash content. When coal is incinerated with oxygen, it takes at least 15 min to determine the ash content. Even then some time may be lost in passing on the data. Therefore, this discontinuous and time-consuming method does not make a suitable starting point for checking, re-adjusting, or modifying the production process. Since it was not possible to accelerate incineration by mechanization and automation, another type of rapid continuous analysis had to be found. This would have to depend on some coal characteristic closely linked with ash content. At the Central Laboratory of Dutch State Mines, Dijkstra and Sieswerda found that the absorption coefficient for X-rays was suitable for this purpose. An apparatus based on the measurement of this characteristic was developed. Named CendreX,* this patented equip- *A Stamicarbon N. V. registered trademark. ment, used in combination with a sampler and conditioning apparatus, permits continuous determination of ash content with satisfactory exactness to within 3 min.t At the American Mining Congress meeting of May 1961, Log A. Updegraff, surveying aspects of continuous analyaia, reported on the CendreX appartus (Mining Congress Journal, August 1961). Since the first Condition for correct ash determination, whatever the method used, is always a sample taken in the right way, some practical aspects of sampling will be discussed first. SAMPLING In coal handling operations, each grain has its characteristic properties. In both the cross-sectional and longitudinal direction of the product stream the mixture of these grains is imperfectly blended. The elimination of the factor of segregation between the cross-sections from the direction of the stream is the principal aim of continuous analysis. Therefore, the samples to be analyzed are withdrawn in various places from the segregated product stream in such a way that they form a semi-continuous flow. In order to be truly representative of the product stream, the sample flow must fulfil two conditions: 1) The sample flow must be sufficiently large to insure that adventitious differences between the composition of the product stream and sample flow will be as small as possible. 2) All grains through the entire cross section of the product stream must have an equal chance to get into the sample flow. Since there is always a segregation through the cross section the sample flow will have a bias if the sampler collects only part of this section. In order to prevent the volume of the sample flow from becoming too large, the cross sections are taken discontinuously. However, this discontinuity gives rise to the adventitious differences that arise between the composition of product stream and the sample flow, and these differences become greater and are more deranging as the fluctuations follow each other more quickly. Moreover, the intervals between the morrnents of sampling mean a delay in the analysis. The aim will, therefore, be to collect small samples, or in other words thin cross-sectional increments, taken at sufficiently high frequencies. The following points should also be taken into account: 1) The smallest dimension of the openings in the sample collector must be equivalent to at least 3 d in

Jan 1, 1962

By P. S. Kotval, H. Hahell

PRECIPITATION of M23C6 carbides at grain boundaries in austenitic steels and nickel base superalloys has received considerable attention. Hatwell and Berghezan,1 in a study using carbon extraction replicas, observed that dendritic growth of the M23C6 carbide phase occurred at grain boundaries in austenitic steels. Merrick and Nicholson2 have observed that in thin foils of "Nimonic 75" alloy the precipitation of M23C6 carbide was discontinuous at grain boundaries. Lewis and Hattersley3 have suggested that the type of M23C6 precipitation observed in Ni-Cr austenites represented the early stages of discontinuous precipitation. In a more recent study, Singhal and Martin4 have concluded that grain boundary M23C6 precipitation involves the migration of an austenite grain boundary by a mechanism very similar to that proposed by Tu and Turnbull.5 Tu and Turnbull's suggestion essentially involves grain boundary migration under the driving force arising from the difference between the surface free energies of the opposite sides of the plate. Thus, Singhal and Martin's observation4 implies that the first stage of discontinuous precipitation has taken place and that the grain boundary has provided a diffusion short circuit for the sub-stitutional solute atoms (principally chromium) which assist the preferential growth of the M23C6 plate in contact with the grain boundary. However, no evidence of the characteristic cellular morphology typical of discontinuous precipitation was found in Singhal and Martin's studies. Presumably, this is due to the low volume fraction (i.e., low supersaturation of solute) of the precipitating carbide reported by Singhal and Martin.4 Recently, Raymond6 has studied precipitation of the M23C6 carbide in Incoloy alloy 825 and shown that the growth of this phase is perpendicular to grain boundaries at 1400°F and in the plane of the grain boundary at 1700°F. The former aging condition resulting in discontinuous or "cellular" precipitation. Raymond has suggested an explanation for this behavior based on the relative rates of chromium diffusion by volume and grain boundary diffusion at the two different aging temperatures. In the course of a recent investigation on precipitation behavior in several ' strengthened superalloys, precipitation of M23C6 carbide at grain boundaries was studied. Under conditions of a high degree of supersaturation, the M23C6 carbide precipitates in the discontinuous or cellular morphology in Waspalloy (Ni-18.51 Cr-2.0 Fe-3.53 Mo-1.16 Al-2.78 Ti-0.09 C). This note presents electron microscopy observations of this mode of precipitation and its effect on mechanical properties. Specimens of Waspalloy after "solution" heat treatment at 1950°F show essentially single phase matrix with a few residual particles of "primary" MC carbide. In normal commercial heat treatments, precipitation of Ni3(Al,Ti) ordered fcc r' phase occurs throughout the matrix and M23C6 precipitates as globular particles at the grain boundaries. In these commercial heat treatments the degree of supersaturation during precipitation is low. However, if specimens of Waspalloy are quenched from the solution heat treatment temperature of 1950°F and then aged at an aging temperature where the degree of supersaturation is high, discontinuous precipitation of M23C6 occurs. Figs. 1 and 2 show thin foil micrographs of Waspalloy, solution heat treated at 1950°F, water quenched, and aged at 1292° and 1598°F, respectively, for 500 Fig. 1—Thin foil of Waspalloy, solution heat treated at 1950°F for 1 hr, water quenched, and aged for 500 hr at 1292°F. Magnification 15,500 times. Fig. 2—Thin foil of Waspalloy, solution heat treated at 1950°F for 1 hr, water quenched, and aged for 114 hr at 1598° F. Magnification 13,000 times.

Jan 1, 1970

By Parviz Montazer, Robert King, William Ubbes, Gideon Chitombo

This paper describes the results of a detailed study that was undertaken to define the spatial distribution of permeability within a five meter thick envelope around the CSM/ONWI room. Detailed fracture orientations and distribution were determined through mapping of the walls of the opening, logging of oriented core, and visual examination of borehole walls with a borescope and a T.V. camera. Over 3,500 measurements were made from which the three dimensional distribution of fractures was determined. Two principally different testing equipment designs and various methods of air injection tests were used in all boreholes to identify and characterize conductive fractures. Through analizing the distribution of permeability and fracture index around the room a zone of blast damage of approximately .5 m thickness was delineated. The effect of stress modification seems to extend farther into the host rock to approximately 3.5 m depth.

Jan 1, 1982

THE activity of the principal oil fields of Rumania followed the same course as in 1939. It was marked by (1) collaboration between the various companies, particularly in exploiting oil at great depths with a view to rationalizing the exploitation and decreasing the difficulties inherent in very deep drilling; and (2) economy in the exploitation of the older pools in reducing to a minimum the cost of the extraction and working over of wells by the concentration of productive wells in groups. The pooling arrangement continued at Tintea as a measure of conservation, and exploitation of the unitized region went forward on the basis of the norms established in 1939. The same methods were applied in the fields of Liesti, Ceptura and Boldesti. The petroleum industry had some difficulty in providing the necessary material and the hands for work. Importation of material and machines from the United States was virtually stopped. Substitutes were provided from Germany but particularly useful were certain dispositions made by the local metallurgical industry. Despite the higher cost of the production of local material and machines, they were superior to the German product, the difference in quality justifying the higher price charged as the materials were found to be particularly adapted for the purposes of the petroleum industry. The cost of production was still further raised by the work that was imposed for national defense. The rise in costs per meter drilled was 50 per cent over those of 1939. According to bimonthly tables furnished by the Moniteur du Petrole Roumain, the deepest well completed in 1940 was an exploratory well, No. 201 of the Concordia company, drilled at Tintea and suspended at 3338 meters. This depth was reached toward the close of 1939 and the well was not deepened in 1940 became of large deviation from the vertical. The record for productive wells had been held by No. 429 at Tintea, drilled by Unirea to a depth of 3200 m., and in 1938 well No. 317 Cocorasti-Mislea, of the Colombia company, but these records were passed in 1940 by well No. 613 Liliesti of the Con-cordia company, which reached a depth of 3294 m. and had an initial production of 10 tons per day. In 1940, the same number of wells, II, had been drilled to a depth of over 3000 m. as in 1939. Five of these wells are at Tintea and six at Liliesti. Table I lists these very deep holes in the order of their depth. Table i.—Deep Wells Drilled in Rumania in 1940 Initial No. Produc- of Company Field Meters tion, Well Meters Tons per Day 405 Colombia......... Liliesti 3,001 10 629 Unireu............ Tintea 3,005 73 426 Unirea............ Tintea 3,050 48 410 Colombia. ........ Liljesti 3,055 30 627 Concordja (Unirea). Liliesti 3,072 75 430 627ConcordjaConcordia (Unirea). (Unjrea 3,II9 30 618 Colombia......... Liliesti 3,168 70 24 Steaua Romana. . . Tintea 3,184 18 412 24Unirea............ Tintea 3,211 23 613 Concordia......... Liliesti 3,294 10 Production in Rumania in 1940 reached 5,813,000 tons, in contrast to 6,~40,0oo tons in 1939, a decline of 427,000 tons, or 6.8 per cent. Drilling reached 241,500 m., in

Jan 1, 1941

THE activity of the principal oil fields of Rumania followed the same course as in 1939. It was marked by (1) collaboration between the various companies, particularly in exploiting oil at great depths with a view to rationalizing the exploitation and decreasing the difficulties inherent in very deep drilling; and (2) economy in the exploitation of the older pools in reducing to a minimum the cost of the extraction and working over of wells by the concentration of productive wells in groups. The pooling arrangement continued at Tintea as a measure of conservation, and exploitation of the unitized region went forward on the basis of the norms established in 1939. The same methods were applied in the fields of Liesti, Ceptura and Boldesti. The petroleum industry had some difficulty in providing the necessary material and the hands for work. Importation of material and machines from the United States was virtually stopped. Substitutes were provided from Germany but particularly useful were certain dispositions made by the local metallurgical industry. Despite the higher cost of the production of local material and machines, they were superior to the German product, the difference in quality justifying the higher price charged as the materials were found to be particularly adapted for the purposes of the petroleum industry. The cost of production was still further raised by the work that was imposed for national defense. The rise in costs per meter drilled was 50 per cent over those of 1939. According to bimonthly tables furnished by the Moniteur du Petrole Roumain, the deepest well completed in 1940 was an exploratory well, No. 201 of the Concordia company, drilled at Tintea and suspended at 3338 meters. This depth was reached toward the close of 1939 and the well was not deepened in 1940 became of large deviation from the vertical. The record for productive wells had been held by No. 429 at Tintea, drilled by Unirea to a depth of 3200 m., and in 1938 well No. 317 Cocorasti-Mislea, of the Colombia company, but these records were passed in 1940 by well No. 613 Liliesti of the Con-cordia company, which reached a depth of 3294 m. and had an initial production of 10 tons per day. In 1940, the same number of wells, II, had been drilled to a depth of over 3000 m. as in 1939. Five of these wells are at Tintea and six at Liliesti. Table I lists these very deep holes in the order of their depth. Table i.—Deep Wells Drilled in Rumania in 1940 Initial No. Produc- of Company Field Meters tion, Well Meters Tons per Day 405 Colombia......... Liliesti 3,001 10 629 Unireu............ Tintea 3,005 73 426 Unirea............ Tintea 3,050 48 410 Colombia. ........ Liljesti 3,055 30 627 Concordja (Unirea). Liliesti 3,072 75 430 627ConcordjaConcordia (Unirea). (Unjrea 3,II9 30 618 Colombia......... Liliesti 3,168 70 24 Steaua Romana. . . Tintea 3,184 18 412 24Unirea............ Tintea 3,211 23 613 Concordia......... Liliesti 3,294 10 Production in Rumania in 1940 reached 5,813,000 tons, in contrast to 6,~40,0oo tons in 1939, a decline of 427,000 tons, or 6.8 per cent. Drilling reached 241,500 m., in

Jan 1, 1941

By John T. Norton, Matthew J. Donachie

Residual lattice strai?zs were produced in 2024 aluminum and ingot iron by uniaxial tensile deformation. These strains were rneasured on the original surface and ulith depth below the surface. The strains conformed approximately to those from a macroscopic stress distribution but they were not truly macroscopic in nature. The exact mechanism which apparently causes the coherently difi9,acting region of each grain to behave as if macroscopically stressed was not determined. MACROSCOPIC stresses in metals produce strains in the lattice which result in X-ray line broadening and line displacements. The latter effect can be utilized in a technique for determining stresses in metals as first shown by Lester and born.' Subsequent advances in technique have enabled the X-ray method of stress measurement to be satisfactorily applied to many problems involving residual stresses of a macroscopic nature, such as those due to welding, grinding, shot-peening, and so forth. In the case of stresses such as those described above, the correlation of X-ray- and mechanically determined data has been generally good. However, plastically extended polycrystalline metals have sometimes been reported2 to show line displacements upon release of the applied tensile load, yet the nature or origin of the residual lattice strains, rls, producing these displacements has never been clear. As will be pointed out, this lack of clarity regarding the macroscopic or microscopic nature and origin of these stresses casts doubt on the validity of results achieved by the commonly accepted techniques of X-ray stress measurement. This anomalous behavior requires clarification to remove the doubts concerning X-ray stress measurement. The present paper is the result of an investigation of the interesting behavior of such plastically extended polycrystalline metal bodies. The studies were originated to carry out the following tasks: 1) Observe whether a residual lattice strain is produced as a result of plastic extension and show whether any residual lattice strains produced can be related to the usual concept of a macrostress. 2) Examine the origin of any residual lattice strains observed. 3) Consider the implications or consequences of the existence of such residual lattice strains on the problem of X-ray stress measurement. THEORY 1) Lattice Strains. The theoretical developments necessary for the treatment of lattice strains and their relation to stresses follow from the classical theory of elasticity and have been adequately covered by arrett. For an isotropic solid under homogeneous deformation, it can be shown that, for uniaxial stresses where Dl is the macrostress acting in the longitudinal direction; E$L is the lattice strain in the plane defined by the surface normal and the longitudinal direction at an angle, , from the surface normal; ET is the similar strain in the transverse plane; E is Young's modulus; and v is Poisson's ratio. Eq. [2] is independent of angle + and Eq. [I] is a linear function of sin2, see Fig. 1, and can be solved analytically for DL if E and u are known and EL is measured. Thus, a uniaxial macrostress will be indicated by a linear E,L vs sinZ plot and a

Jan 1, 1962

By F. E. Pawlek, J. K. Gerlach

The chloridizing roasting of ores is applied when metal sulfides and oxides are to be converted into soluble or volatile compounds. The chlorine required is either obtained from the admixed chlorides of sodium or calcium or added in the gaseous state. In the first part of the investigations the reaction rate of the chlorides of sodium or calcium with gas mixtures of SO,-0, or SO ,-O2 ,-SO , was measured. The rate for reactions with gas mixtures SO2-O2 is ThE chloridizing roasting of ores is applied when metal sulfides and oxides are to be converted into soluble or volatile compounds. At present the process is mainly applied to produce nonferrous metals which occur in pyrite cinders in small concentrations. Thereby the nonferrous metals are converted into water-soluble, acid-soluble, or volatile compounds whereas all the iron remains as insoluble oxide. The chlorine required is either obtained from the admixed chlorides of sodium or calcium or added in the gaseous state. The reactions occurring during the roasting process can be divided into two groups: solid-solid reaction and gas-solid reaction. The reactions between solids proceed by means of solid-state diffusion and are therefore of low velocity. The heterogeneous reactions between solids and gases of the roasting atmosphere5 are high-velocity processes and determine the velocity of the chloridizing roasting. These gas-solid reactions shall be the subject of the paper presented. In order to investigate the still little-known processes which occur during the chloridizing roasting 6-' the complex reaction is split into several partial steps. First the reactions of NaCl and CaCl, with gas mixtures of SO2 and 0, have been investigated at temperatures between 500" and 600°C by measuring the weight increase of the samples. The gas mixtures used in this series of experiments had first variable compositions, then the amount of SO 2 had been increased. Furthermore the influence of Fe 2 O3 admixtures upon these reactions, the behavior of pure Fe 2 O3 with the gaseous reactants, and the chlorination of the sulfides of lead, copper, nickel, and zinc have been investigated. FORMATION OF GASEOUS CHLORINE Pyrite cinders are never completely roasted and therefore contain still a small amount of sulfide sulfur. When heated again in air, this sulfur is converted into SO,. Accordingly the formation of chlorine can first be described by the reactions: dependent on the composition of the gas phase. If more than 1 pct SO 3 is added to the roasting gas, the reaction rate is determined only by the concentrations of the SO,. In the second part the reactions between chlorine and metal sulfides are discussed. The rate of formation of gaseous chlorine is higher by me order of magnitude than is the reaction rate between ZnS and chlorine. The reaction rate of NiS and PbS lies considerably below that of ZnS. The conversion rate of both pure Fe 2 O 3 and Fe 2 O 3 containing NaCl or CaCl2 when reacting with SO2-O2, mixtures with and without SO3 portions was measured at temperatures of 500", 550°, and 600°C. The weight increase of pressings was determined by means of a spiral balanceg and the reaction rate calculated therefrom according to Eqs. [ll to [31 and [5] to [7]. The prepared samples were suspended on a platinum filament in a vertically mounted tube of mullite (ID 4 cm, length 110 cm) which could be heated by a resistance tube furnace. The platinum filament was tied to the lower end of the spiral balance. A supremax glass tube (length 70 cm) was mounted gas-tight on top of the reaction tube. The unit was sealed up at its top by a ground-in stopper which was holding the spiral balance with the sample. The spiral balance therefore hung outside the high-temperature region of the furnace. Fig. 2 shows the experimental arrangement schematically. While lowering the sample into the reaction tube pure nitrogen was flowing through the reaction zone providing a protective atmosphere. After the sample had reached the reaction temperature within approximately 1 min, the protective gas was replaced by the sulfur dioxide-oxygen reaction mixture. It took about 30 sec until the mixture filled the tube homogeneously. A Ni/NiCr thermocouple placed in the center of the furnace where the sample hung during the measure-

Jan 1, 1968

By E. C. W. Perryman

The recovery of X-ray line broadening, hardness, and electrical resistivity from cold worked AI-Mg alloys has been investigated. The results, together with those from density measurements, suggest that magnesium atoms freeze in the excess vacancies formed by cold working, and that this affects the climb of dislocations during the recovery process. PREVIOUS work1, " has shown that while 1 pct Mg increases the activation energy for recrystalliza-tion, it decreases the activation energy for the recovery of mechanical properties and decreases the subgrain size both after cold working and annealing. A similar result has been reported by Varley2 for an A1-2 pct Mg alloy. With plastic deformation at high temperatures, McLean and Farmer' and Rachinger have found that magnesium appears to retard the motion of dislocations and, furthermore, they find little or no effect of magnesium on the size of subgrains formed during high temperature deformation. In view of the apparent contradictions as to the effect of magnesium on subgrain size, the recovery process in Al-Mg alloys has been investigated more thoroughly by studying the annealing out of X-ray line broadening, hardness, and electrical resistivity from alloys cold worked at room temperature. Material Used—The chemical analyses of the alloys are given in Table I. Fabrication—The material used was cold rolled 20 pct at room temperature, the grain size prior to the last cold rolling operation being similar to that used in previous work; i.e., 230. The experimental procedure for annealing, determination of X-rav half-veak breadth. hardness measurement, electEica1 resistivity, and density and metallographic examination was exactly the same as previously described." Variation of X-Ray Half-Peak Breadth with Annealing Time—Isothermal annealing curves at 100°, 200°, and 250°C were obtained for material cold worked 20 pct. The half-peak breadth of the (333) Ka, line directly after cold working is shown as a function of magnesium content in Fig. 1. Only with the 2.87 pct Mg alloy was overlapping of the a, and n.. reflections observed to any appreciable extent. To separate these, Rachinger's method' was used. Typical isothermal annealing curves are shown in Figs. 2 and 3 for 100" and 200°C, respectively. These curves are similar to those obtained previously for super-purity aluminum except that the

Jan 1, 1957

By H. C. Casey, M. B. Panish

The roles of the phase diagram and the diffusion and solubility analyses in the selection of sources for the diffusion of zinc into GaAs are discussed. Isothermal sections of- the phase diagram are described at 1000°, 775°, 744°, and 700°. Below 744° the three solid phases, Zn3As2, GaAs, and ZnAsz, may be in equilibrium. In the composition regions where the three solid phases are in equilibrium, the partial pressures of the components do not vary with composition and there is no liquid phase. A diffusion source composition within that region containing 5, 50, and 45 at. pct Ga, As, and Zn was selected to yield reproducible diffusion profiles without surface damage. The 5/50/45 ternary source Provides a significant improvement in the reproducibility and planarity of- the zinc diffusion as compared with other zinc diffusion sources that result from starting with elemental zinc, dilute solutions of zinc in gallium, or various combinations of zinc and arsenic. Several experimental diffision profiles for the 5/50/45 diffusion source have been determined. The profiles are very steep in the region of the junction and produce devices that exhibit step junction behavior. The junction depth varies as the square root of time. Diffusion at 700°C for 4 hr gives a 5-µ junction depth and a surface concentration of 2.4 x1020 cm-3. The surface concentration is enhanced by a factor of three and the junction depth decreased by a factor of ten as compared with diffusion with a starting source 01- elemental zinc. The differences in dijyusion behavior with these two sources are due primarily to the approximately 10' greater equilibrium As4 partial pressure for the 5/50/45 source. ThE most common technique for the preparation of GaAs p-n junctions for diverse applications ranging from switching diodes to injection lasers has been to diffuse zinc into the solid from the vapor phase. The zinc impurity has generally been provided by introducing into a diffusion ampoule elemental zinc, dilute solutions of zinc in gallium, or various combinations of zinc and arsenic. For the purpose of eliminating surface deterioration, zinc has been diffused into GaAs through SiO2 films1 and from zinc-doped SiO2 films.2 During a study of the injection and recombination mechanisms in GaAs junctions, we found that these diffusion techniques either resulted in nonreproducible diffusion profiles and nonplanar junction interfaces or were extremely inconvenient to use. An unpublished report by Allen and pearson3 emphasized that an understanding of diffusion requires relating the diffusion conditions and system compositions to the ternary phase diagram. Recent studies have made it possible to relate the effect of starting source composition on the GaAs sample surface and diffusion profile reproducibility and, in addition, to estimate the expected surface concentration and zinc diffusivity. These studies include the Ga-As-Zn phase diagram,415 the determination of the incorporation reaction for zinc as a substitutional impurity,6 and the analysis of the concentration dependence of the diffusion coefficient.' In this paper the role of the phase diagram in the selection of the starting diffusion source composition is illustrated, and an application of the diffusion and solubility analyses is used to demonstrate their utility in the estimation of surface concentration and diffusivity for various starting source compositions. Consideration of the isothermal sections of the ternary phase diagram shows that below about 744° C a composition region exists where the three solid phases Zn3As2, GaAs, and ZnAs2 are in equilibrium without a liquid phase. In this region the partial pressures of the components do not vary with composition, and thus the surface concentration and diffusivity depend only on temperature. A diffusion source composition within that region containing 5, 50, and 45 at. pct Ga, As, and Zn was selected. As will be described in detail, this diffusion source yields reproducible diffusion profiles without surface damage, planar junction interfaces, and steep profiles that result in devices with step junction behavior. Only closed diffusion systems are considered. Open or flowing vapor systems require the maintaining of constant vapor pressures in the flowing gas and represent control problems outside the scope of this discussion.

Jan 1, 1969

By E. J. Dulis, G. V. Smith

AS reported several years ago,' nitrogen may be taken up from the atmosphere by austenitic Cr-Ni steels during creep or creep-rupture tests. This was indicated by chemical analysis and by the appearance of a new microstructural phase, or phases, tentatively identified as chromium nitride (S), at the surface or at the intergranular cracks associated with fracture. The nitrogen pickup was observed to be dependent on time, temperature, and deformation. In a more recent investigation, a sample was obtained in which there was sufficient of the precipitate to suggest that it could be readily identified by X-ray diffraction. This sample had been taken from a 1/4 in. diam creep-rupture specimen of annealed, type 304L stainless steel of the following initial composition: C, 0.03 pct; Mn, 0.65; P, 0.010; S, 0.019; Si, 0.54; Cr, 19.50; Ni, 12.02; N, 0.031; and Al, 0.005. The specimen had ruptured after 10,470 hr at 1500°F (2000 psi). In this case nitrides were distributed across the whole section of the sample, Fig. 1. The precipitate occurred both at the grain boundaries and within the grains; the latter precipitate had in some cases the appearance of pearl-ite, and in others was distinctly Widmanstatten. Chemical analysis of the sample after test showed 0.64 pct "soluble" nitrogen (soluble in 1:1 hydrochloric acid: water) and 0.18 pct "insoluble7' nitrogen (insoluble in the hydrochloric acid solution but dissolved by fuming sulphuric acid). For identification of the precipitate by X-ray diffraction, the matrix in the surface layer of the specimen was dissolved by prolonged attack in an alcoholic solution of picric and hydrochloric acids. The appearance of the specimen surface after such etching is shown in Fig. 1c. The diffraction pattern of the surface-concentrated precipitate was obtained with a recording spectrometer in both the forward and back-reflection regions (the latter by adapting a special fixture to the conventional X-ray unit). The observed X-ray diffraction lines, Table I, show the presence of Cr,N and CrN; the agreement with interplanar spacings calculated from reported data2,3 is quite good. Since it has been suggested' that CrN dissolves only in concentrated sulphuric acid, whereas Cr2N dissolves in dilute hydrochloric or sulphuric acids, an effort was made to distinguish between the two nitrides. This proved possible, inasmuch as etching in a dilute solution of hydrochloric acid gave a sample in which microscopic examination showed that much of the Widmanstatten-pearlitic precipitate within the grains had been eaten out, leaving the grain boundary precipitate in relief, and which, when examined by X-ray diffrac-

Jan 1, 1953

By E. Maxwell, C. J. Bechtoldt, H. C. Vacher

IN the course of an investigation of the properties of metals at low temperature there was occasion to determine the constitution of four iridium-osmium alloys. There is very little information in the literature1 on the constitution of synthetic Ir-0s alloys. Zvyagintzev' s has made a comprehensive study of different natural Ir-0s alloys and concludes that alloys containing more than 32 pct 0s have the close-packed hexagonal structure of osmium, whereas those containing less than 32 pct 0s have the face-centered cubic structure of iridium. The alloys studied in this work were prepared by the American Platinum Works, Newark, N. J., and were received in the form of fragments approximately 1.5 mm average diameter. The fragments had been obtained by crushing ingots made by fusing charges of iridium and osmium under an arc and air cooling. The ingots were not given a homogenizing heat treatment. Sample fragments Table I. Results of X-Roy Diffraction and Microscopic Examinations Phases Present as Determined by X-ray Diffraction Osmium Alloy Close- Iridium Face- Packed Centered Osmium, Iridium, Hexagonal Cubic Mlcro- WtPot Wt Pct Structure Structure scope 0 99.9 None Present 1 23.6 76.4 None Present 1 38.7 61.3 Present Present 2 59.4 40.6 Present Present 2 79.0 21.0 Present Not detected 2 99.9 0 Present None 1 Note: Chemical analyses of the iridium, osmium, and alloys were furnished by the American Platinum Works. of the iridium and osmium used in making the alloys also were included. Several fragments of each metal and alloy were examined microscopically and by X-ray diffraction. For the X-ray method the fragments were crushed further to pass a 270-mesh screen, then sealed in evacuated fused-silica tubes, heated to 1100°C for 18 hr, and allowed to cool in the furnace. Powder X-ray diffraction patterns were obtained from the annealed fragments by means of a Norelco camera having a diameter of 114 mm, and unfiltered cobaIt radiation. For the microscopic examination several fragments in the as-received condition were mounted in Melmac, (American Cyanamid Co.) and ground using the conventional series of abrasive papers. The polishing was done with 0-2 diamond abrasive on a Microcloth (Buehler Ltd.) lap, wet with xylene. After polishing, the surface was etched electrolytically in a 10 pct solution of chromic acid or in a 10 pct solution of potassium cyanide. Both reagents attacked the osmium-rich constituent, whereas the iridium constituent was attacked slightly by the chromic acid reagent and not noticeably by the potassium cyanide reagent. The results of the X-ray diffraction and microscopic examinations are summarized in Table I. Fig. 1 shows the microstructure of a 21 pct Ir-79 pct 0s alloy. The results indicate an appreciable solid-solu-bility range of osmium in iridium as was reported by Zvyagintzev.' The solid-solubility range of iridium in osmium is more restricted, apparently less than 21 pct Ir. This implies a large range of composition in which two phases can coexist that was not reported by Zvyagintzev.

Jan 1, 1955

[For the year ending February, 1936 PRESIDENT AND DIRECTOR HENBY A. BUEHLER3 ROLLA, Mo. PAST PRESIDENTS AND DIRECTORS FREDERICK M. BECKET1 NEW YORK, N. Y. HOWARD N. EAVENSON2 PITTSBURGH, PA.]

Jan 1, 1936

Secretary's Note.—M. Beutter's introductory remarks, being simply a resume of Prof. Hone's paper, with a disclaimer of the intention to criticise it, have been omitted, and the remainder of this contribution lias been somewhat condensed, without omitting any essential statements. M. Beutter, St. Etienne, France* (communication to the Secretary†):—Professor Home observes in $ 47 of his paper that the fluid-compression of steel diminishes piping by forcing the liquid and viscous metal, while the pipe is forming, or after it has formed, into the space so produced, and proceeds to study the different systems of compression, alluding to the four principal ones: Whitworth, Illingmorth, Williams, and Harmet. Having now for many years had in use the last-named process, that of M. Henri Harmet, I shall attempt to explain the difference between it and the three other processes named. The Harmet process does not diminish or close the pipe after it has formed, but prevents it from forming; and I may add that it is the only one of the four which produces this result. It is true that the Whitworth process diminishes the interior hollow by localizing it around the central axis of the ingot, which is afterwards removed by trepanning the hollow forg-ings for which this process has been, I believe, always exclusively used. The Illingworth and Williams processes, which, in my opinion, are applicable only to small ingots, of necessity allow the pipe to form, or (to use the expression of Professor Howe) they allow the surface of the lake of liquid steel to sink into the interior of the ingot, since they involve waiting a certain time before compression, so that (in the case of the Williams process) the ingot-mold can be opened without danger, or (in the case of the Illingworth process) so as to avoid the risk that the steel may enter the grooves produced by the removal of the distance-bars. During the time required for

Jan 1, 1908

By Stanley C. Herold

A few hates on the occurrence and significance of mud volcanoes in Colombia may be of interest at the present time, owing to the renewed activity in geological exploration of the coastal regions bordering the Caribbean Sea. The best-known volcanoes are found a few miles from the seacoast. One is situated to the south of Puerto Colombia; the second, to the east of Cartagena near the village of Turbaco; and the third, near the village of Puerto Escondido south of the Sinu River. Others are reported in more inaccessible localities. Usually they stand 2 1/2 or 3 ft. (0.762 or 0.914 m.) above the surrounding ground at the crater, though several craters from 10 to 20 ft. -(3.04 to 6.09 m.) "apart will often build up an extensive mound at low gradient. The shallow mound may cover 1/2 or 3/4 acre (0.2 to 0.3 ha.) with an elevation of 12 or 15 ft. (3.65 or 4.57 m.) at the, center. The craters are formed of hardened blue clay; the inside diameters vary from 14 to 24 in. (35.56 to 60.96 cm.). The rim is continuous, except on one side where there is usually a cut 3 or 4 in. deep, thus allowing an overflow. The craters are filled to the' rim-cut with a thick mixture of blue clay mud and water, which is kept in agitation by escaping gas. Fig. 1 shows the bubble in the act of bursting and Fig. 2 the appearance of the surface of the viscous fluid a second or so later. The frequency of the explosions is determined by the weight of the column of fluid in the neck of the volcano, consequently, such explosions are not synchronous in a group of craters. Ordinarily, there arc two or three explosions in about 3 minutes. The supply of gas is small but steady and sufficient pressure must accumulate before the bubble can enter the column of fluid. The water is derived from the surface and enters the scdirnentary strata not far distant from the volcano. During long dry seasons, as the supply of water fails the volcano dries and geyser action ceases. The temperature of the muddy fluid is normal; the gas is dry and inflammable. - No petroleum products come with the gas. On the surface of the fluid, there is sometimes a dark brown streaky scum, which

Jan 1, 1920

Question 1—1s Structural Deformation of Some Character Always Necessary for the Migration of Mineralizing Solutions. Especially in Limestone or Other Dense Rocks Discussion by: A. M. Bateman.........120 S. F. Kelly........... 125 C. H. Behre. Jr........118.123 G. B. Langford......... 123 T. M. Broderick.........121 H. E. McKinstry......... 116 R. H. Clarke.......... 123 D. H. McLaughlin........ 118 J. D. Forrester for M. H. Gidel . . 11.4 W. H. Newhouse......... 123 G. M. Fowler......112. 116. 121 R. H. Sales.......... 116 L. C. Graton..........121 Edward Sampson......... 122 R. D. Hoffman.........120 J. 8. Stevenson.......... 117 I. B. Joralemon.........121 L.B.Wright........... 112 Question 2—What Are Some of the Chemical and Physical Characteristics in Certain Beds within a Limestone Formation that Determine Their Favorable or Unfavorable Aspects as Reservoirs for Ore and Other Introduced Minerals? Drscussion by: G. W. Bain....... 127 G. M. Fowler....... 131 C. H. Behre, Jr. ..... 131 L. C. Graton....... 128 J. S. Brown. ...... 126 G.. F. Loughlin...... 128 E. L. Bruce ....... 129 R. H. Sales........ 129 R. H. Clarke...... 130 A. K. Snelgrove....... 130 Question 3—Are There Any Criteria by Which One Can Determine When Mining Operations Have Reached the Roots of an Ore Deposit? Discussion by: J. M. Boutwell...... 139 G. B. Langford..... 139 T. M. Broderick..... 138 . G. F. Loughlin...... 135 E. Y. Dougherty..... 137 R. H. Sales...... . 134 G. M. Fowler....... 132 F. A. Thomson..... 136 I. B. Joralcmon...... 132 Edward Wisser:..... 140 General s. F. Kelly................. . ...........145 References...............................146

Jan 1, 1941

Question 1—1s Structural Deformation of Some Character Always Necessary for the Migration of Mineralizing Solutions. Especially in Limestone or Other Dense Rocks Discussion by: A. M. Bateman.........120 S. F. Kelly........... 125 C. H. Behre. Jr........118.123 G. B. Langford......... 123 T. M. Broderick.........121 H. E. McKinstry......... 116 R. H. Clarke.......... 123 D. H. McLaughlin........ 118 J. D. Forrester for M. H. Gidel . . 11.4 W. H. Newhouse......... 123 G. M. Fowler......112. 116. 121 R. H. Sales.......... 116 L. C. Graton..........121 Edward Sampson......... 122 R. D. Hoffman.........120 J. 8. Stevenson.......... 117 I. B. Joralemon.........121 L.B.Wright........... 112 Question 2—What Are Some of the Chemical and Physical Characteristics in Certain Beds within a Limestone Formation that Determine Their Favorable or Unfavorable Aspects as Reservoirs for Ore and Other Introduced Minerals? Drscussion by: G. W. Bain....... 127 G. M. Fowler....... 131 C. H. Behre, Jr. ..... 131 L. C. Graton....... 128 J. S. Brown. ...... 126 G.. F. Loughlin...... 128 E. L. Bruce ....... 129 R. H. Sales........ 129 R. H. Clarke...... 130 A. K. Snelgrove....... 130 Question 3—Are There Any Criteria by Which One Can Determine When Mining Operations Have Reached the Roots of an Ore Deposit? Discussion by: J. M. Boutwell...... 139 G. B. Langford..... 139 T. M. Broderick..... 138 . G. F. Loughlin...... 135 E. Y. Dougherty..... 137 R. H. Sales...... . 134 G. M. Fowler....... 132 F. A. Thomson..... 136 I. B. Joralcmon...... 132 Edward Wisser:..... 140 General s. F. Kelly................. . ...........145 References...............................146

Jan 1, 1941