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By A. D. Schwope, L. R. Jackson, A. M. Hall

In the course of an extensive investigation of the comparative properties of several types of copper, data were obtained on the cold working and subsequent recovery and recrystallization of the copper. In this paper, relations between the degree of cold work and the course of re-crystallization are developed. In particular, it is shown that the course of recrystallization over long periods of time and at low temperatures can be predicted with reasonable accuracy from short-time high-temperature recrystallization data. Materials Used in The Investigation Three types of copper were used in this investigation; these were tough pitch, OFHC, and OFHC copper with 15 oz per ton of silver added identified herein as Lots C, D, and F, respectively. The material was supplied by the American Metal Co. Ltd., and processed by the Rome Cable Co. The analyses of the three types of copper are given in Table I. Originally, it started as wire bars 4 X 4 X 54 in. These bars were heated to 871° C in air and hot rolled to % in. rod. This rod was cold drawn to 0.204 in. rod (70 pct reduction) in three passes and annealed at 427°C for 4 hr. A portion of the 3/8 in. rod was saved for more detailed cold-drawing experiments. Starting with the annealed 0.204 in. rod, hard-drawn wires were produced by cold drawing to 0.081 in. wire in 7 passes (84.4 pct reduction in area). Half-hard wires were made by cold drawing the 0.204 in. rod to 0.102 in. wire, (75 pet reduction) in 6 passes and annealing at 427'C for 4 hr. This annealed wire was then drawn to 0.081 in. wire, (37.1 pet reduction) in 2 passes. Square rod was made by hot rolling wire bars to Re in. rod in 8 passes. This rod was then cold drawn to 0.445 in.-diam rod and annealed for 346 hr at 538°C. It was then cold drawn to 0.325 in. rod and again annealed at 538°Cf or 3 1/2 hr Hard square rods were then made by cold rolling this material to 0.257 X 0.257 in. rod, a reduction in area of 20.5 pct. Half-hard square rods were made by cold rolling to 0.268 x 0.268 in. square, annealing for 3 1/4 hr at 538°C and cold rolling to 0.257 x 0.257 in., a reduction of 8.5 pct. Soft wire or rod was made from all types of copper by annealing the hard-drawn material at 343°C for 3 hr in steam. The grain size of the annealed 0.081 in. wire varied slightly among the three lots: from o.o15+.oz5 mm in the silver-bearing OFHC to 0.035-0.045 mm in the OFHC copper. The annealed 0.257 in. wires were more uniform in grain size, averaging about 0.035-0.045 mm. Representative structures are shown in Fig I. Effect of Cold Drawing and Tensile Strain on Strength of Copper Conventional tensile tests were performed on the three types of copper in the various degrees of hardness described above. Results of these tests are tabulated in Table 2. The results in Table 2 are 6

Jan 1, 1949

By Robert L. Akre

When Marco Polo visited China in the 13th century, no one knew what black powder was except the Chinese: they knew enough to make dazzling fireworks with it. But the realization that black powder could also do useful work came much later and, like all important discoveries, it altered the course of history. It was in the 14th century that black powder was first used to break rock in a very crude way: there were no drills and the powder was simply poured into cracks and exploded by setting it afire. Because its energy value was pretty low, the need for something more powerful was felt when the industrial revolution arrived.

Jan 6, 1976

By Arnulf Muan, W. C. Hahn

Activities of "FeO" in "FeO"-MgO solid solutions have been determined in the temperature interval 1100" to 1300"C by equilibrating oxide samples with pure metallic iron in atmospheres of known oxygen partial pressures. The end members "FeO" and MgO form a complete solid solution series. The system shoztls a considerable positive deviation from Raoult's law. A large amount of data has been accumulated during the past 50 years on stability relations existing among various crystalline and liquid phases in oxide systems of importance in metallurgical processes. By comparison, very little is known about the thermodynamic properties within the various homogeneous phases present in the systems, particularly the crystalline phases. The present paper deals with determination of activities as a function of composition in solid solutions of wüstite ("FeO") and periclase (MgO). Such solid solutions ("Magnesiowustites") have simple sodium chloride structure and are known to be continuous between the end members at elevated temperatures (> 1000°C) and strongly reducing conditions such as prevail in contact with metallic iron. Wiistite has a defect structure in which the ratio of oxygen to iron varies and never has as low a value as 1:1 corresponding to the simplified formula FeO. Within the range of stability of this phase, the composition changes between a maximum oxygen content of approximately 25.6 wt pct (corresponding to the formula FeO.83O) and a minimum oxygen content of approximately 23.2 wt pct (corresponding to the formula Fe0-96O). The activity data to be reported in the present paper are based on using as standard state the wüstite which is in equilibrium with metallic iron at a particular temperature, i.e., "FeO" of minimum oxygen content at each temperature. For sake of simplicity, the formula FeO will be used to represent the wustite phase in the remainder of this paper. Consider the reaction 2 FeO solid solution = 2 Femeta1 + Ozgas in which FeO dissolved in another oxide dissociates to metal and gas. The activity of FeO in the solid solution, relative to "pure FeO" in equilibrium with metallic iron as a standard state, is then expressed as Here Po, and po2 * are the partial pressures of oxygen of the gas phase in equilibrium with metallic iron and the oxide solid solution or "pure FeO", respectively. The equation holds only if the metal phase is essentially pure Fe. The oxide combinations used in the present investigation fulfill this requirement. Magnesia is so much more stable than FeO that for all practical purposes aFe = 1 in the metal phase present in all mixtures used in this investigation. I. EXPERIMENTAL METHOD 1. General Procedure. The experimental method used was analogous to that developed by Foster and Welch1 and used recently by Hahn and Muan.2 It consisted of four steps: a) Determination of the equilibrium between FeO and Fe. b) Determination of d-spacing change with composition in oxide solid solutions (FeO-WO). c) Equilibration of various members of the solid solution series with a metal phase and a gas phase of known oxygen partial pressure. d) Determination of compositions of solid solutions resulting from step (c) by means of data obtained in step (b). 2. Starting Materials. General Aniline and Film Corp. carbonyl iron powder, type HP, was used as the source of metallic iron. A representative analysis was as follows: Fe, 99.6 pct; C, 0.01 to 0.04 pct; 0, 0.1 to 0.3 pct; N, 0.00 to 0.05 pct. Other elements were present as traces only. Wiistite was prepared from "Baker Analyzed" Reagent grade Fe2O3 of reported analysis as follows: Assay (Fe2O3), 98.8 pct; insoluble in HC1, 0.02 pct; not precipitated by NH,OH, 0.02 pct; Zn, 0.003 pct. Production of wüstite was achieved by a two-step

Jan 1, 1962

By K. I. Savage, S. C. Sun

This paper describes a process developed to recover coal, clays and pyrite from coal wastes. The process consists of fine grinding followed by coal and pyrite flotation which leaves the clays in the flotation pulp. A bituminous coal refuse containing 10% sulfur and 30% carbonaceous material was treated by this method to yield a coal product containing 4% sulfur, 10% ash; a pyrite product containing 45% sulfur (84% FeS2), 1% carbonaceous material; and a clay product containing 2% sulfur (3.5% FeS2). The coal yield was about 89%. The pyrite yield was about 77%. The process steps may be entirely flotation, or gravity separation (hydrocycloning) may be used to increase the pyrite : coal ratio in the flotation feed. Cost estimates for the process show a profit of $2.28 per ton of low pyrite grade refuse, but these do not include labor, maintenance, overhead and plant depreciation. The development of this process consisted of three parts: (1) exploratory tests, (2) op-timazation tests and (3) confirmatory tests. The objectionable qualities that sulfur imparts to coal have been commented upon from early times, and they have become more objectionable as the uses of coal have grown. In whatever form coal takes — raw, carbonized or gasified —the sulfur content remains objectionable, and therefore its compounds are removed as completely as possible. It has long been known that sulfur occurs in coal in different forms. In 1861, sulfur was said to exist in the state of sulfuric acid in combination with a base; in combination with iron as iron pyrites; as bisulfides of iron; and in combination with the organic elements of coal.' Pyritic sulfur is a term loosely used to cover the sulfur associated with iron in its various forms. The mineralogically recognized forms are pyrite (FeS2), pyrrhotite (Fe 1-x S) and marcasite (FeS2). The particle sizes of pyrites vary widely. Isolated grains of marcasite smaller than 15 microns have been found disseminated through coal.2 Hair-like "veins" of pyrite filling cracks in vitrain have been found. At the other extreme, lumps or nodules of pyrites large enough for removal by hand picking have been encountered. Organic sulfur, unlike pyritic sulfur, does not exist as discrete particles, but is instead intimately associated with the coal structure and thus it is impossible to remove it or reduce its concentration by physical or mechanical means.2 In the preparation of coal for its various markets, the pyrite minerals (pyrites) are separated from the raw coal feed. This separation process concentrates the pyrites in the tailings or other waste products. It would be desirable to recover these pyrites for three reasons: (1) Pyrites are potential sources of sulfur and iron. In 1967, for the fifth consecutive year, Free World consumption of sulfur exceeded production.3 Propelled by the shortage, the domestic price of sulfur has risen from $24 to $38 per long ton (bright). (2) The refuse, when placed in piles, becomes ignited. The pyrites (FeS2) bum, giving off SO,. Thus, the pyrites are a cause of air pollution. (3) Also, the pyrites undergo chemical reaction when exposed to air. The refuse is leached by waters which result in stream pollution due to the water-soluble iron and acidic reaction products. Coal refuse also contains coal minerals and clay minerals. Therefore, any process for recovering the pyrites must successfully separate them from the coal and clay minerals. In the study discussed here, ten different bituminous coal refuse samples were successfully upgraded in pyrite content. These samples represented a wide variety of coal waste materials from Pennsylvania and other states. The variabilities of the sulfur and coal contents are shown in Table I. The extremes are Sample J, a high sulfur-low coal, and Sample B, a low sulfur-high coal. Definitions of some of the symbols or terms used in this report are given below: Mesh size—Tyler standard mesh screen sieves with an opening based on the square root of two. Fe —Indicates iron, as determined by a stannous reduction-dichromatic oxidation method. S—Indicates sulfur, as determined by the ASTM "Eschka" method for sulfur in coal.

Jan 1, 1969

By J. Kittl, D. Arias

THE decomposition on cooling of the high-temperature ß bcc phases in copper- or silver-based binary systems usually takes place by a martensitic. massive, bainitic, or pearlitic reaction depending upon the particular conditions of each system. The AgAl system is one of these systems in which a massive or a martensitic transformation can occur upon cooling from the 3 phase field. Recently Hawbolt and Brown1 observed both massive and martensitic transformation products in a 22.7 at. pct A1 alloy. In the present work the massive and the martensitic transformations were investigated in a number of alloys for the composition range between 23.2 and 27.9 at. pct Al. The alloys were prepared using high-purity silver, 99.999 pct, supplied by ASARCO and aluminum, 99.999 pct, supplied by ALCOA. The metals were melted using a graphite or a sintered alumina crucible which was sealed in quartz tubes under an argon atmosphere. The alloys Were remelted to reduce segregation and homogenized in the 13 phase field for 24 hr. The weight of the alloys after homo-genization compared with the initial weight indicating the alloy composition to be within k0.1 pct of the in- tended composition. Chemical analysis of several samples confirmed the estimated alloy composition. All metallographic observations were performed on samples electropolished with ac current using a 10 pct solution of KCN and a stainless-steel electrode. The samples were cut into -1-mm-thick slices, polished, heat-treated in the ß phase field, and quenched in air, ice water, or iced brine. Some heat treatments consisted of a 2-min anneal carried out in air to allow maximum quenching speeds. Other samples were heat-treated in a vacuum of 10"4 torr and quenched using a helium blast in a quenching apparatus described elsewhere.&apos; In both cases, no appreciable losses of silver or aluminum were noted at the sample surface by sectioning and electropolishing. Table I summarizes the microstructure resulting from the various quenching treatments. The composition of the alloys investigated is also indicated on the equilibrium diagram in Fig. 1. The <, hcp phase, typical of a massive ß — cm, transformation, was observed in all alloys. A minimum temperature of 450°C was estimated for this transformation based on preliminary cooling experiments. the results being included in Fig. 1. In these

Jan 1, 1970

By K. H. Adams, T. Vreeland

The basal stress-strain behavior, dislocation density, and strain vale sensitivity of the flow stress uqere measured at room temperature on single crystals oj-zone-refined zinc , 99.999 pct Zn, and zinc containing 0.0025 and 0.02 wt pct Al. No significant change in the stvain rate sensitivity of the flow stress occurs with the addition of aluminum. Changes in dislocation substructure and nonbasal dislocation density were obserrled with the addition of aluminum. The effect of aluminum on the basal slress-strain behavior is explained in terms of changes in nonbasal dislocation density which determines the separation distance of junctions between basal and nonbasal dislocations. The onset of basal slip is associated with the breaking of attractive junctions. The chunge in basal dislocation density was found to be proportional to the one-third power of the plastic shear strain, indepedent of purity. THE effect of impurities in solid solution on the stress-strain behavior of single crystals has been the subject of many theoretical studies. These studies have generally concentrated on the interactions between impurities and dislocations to explain the hardening effeet of impurity additions. The theories that have been proposed include those of yott and Nabarro,&apos;l&apos; Cott-re11; Suzuki; and Fisher. In practice, it is generally difficult to predict the relative importance of the vari- ous effects due to impurities. In addition, secondary effects of impurity additions such as induced changes in dislocation density and substructure in the as-grown crystals have received little attention. Many experimental investigations have been conducted on the effect of impurities on the stress-strain behavior of fcc crystals. Hcp crystals have not received much attention except for the extensive work of Levine et a1.= on magnesium alloy crystals. Stuwe~&apos;&apos; has studied the effect of copper impurity on the critical shear stress of zinc crystals and has interpreted the results in terms of the impurity atmosphere model of Cottrell and Jaswon. This report presents the results of an experimental study of the effect of aluminum additions to zinc on the basal stress-strain curve and the strain rate sensitivity of the flow stress. Etch pit techniques were used to measure and characterize the dislocation density and substructure in the zinc alloy crystals. EXPERIMENTAL PROCEDURE Specimen Preparation. Compression test specimens of four different purities of zinc were prepared from CP grade zinc of 99.999 pct purity obtained from the New Jersey Zinc Co. An analysis of this material furnished by the supplier indicated the following impurities in wt ~ct: Pb = 0.0002; Fe = 0.0002; Cd = 0.00005; other <0.60011. A quantity of material of this grade was further purified by zone refining. Zone refining was carried out under a helium atmosphere by passing a double &apos;One furnace Over a 6-ft-10ng charge at the rate of 2 in. Per hr. * total of ten double zone passes were made before the charge was removed from the furnace. The first one third of each charge was used to grow single crystals. Quantities of two

Jan 1, 1969

By C. van Dijk

In Sept., 1960, a steam-drive project was started in the solution-gas drive area of the Schoonebeek field. A part(ern of three five-spots and one four-spot was selected covering an area of 65 acres. The pay in the project area has good lateral continuity and dips slightly to the northeut; it is about SO ft thick and permeability increases from 1,000 and at the bottom to approximately 10,000 md at the top. The oil originally in place was 12.6 X 10&apos; bbl. The oil has an in situ viscosity of about 180 cp. At the start of the steam drive the cumulative primary production due to. solution-ga.7 drive amounted id 4 Percent of the oil originally in place. Reservoir pressure had dropped about 120 psi and no significant primary re-.serves remained. Some 11.3 million bbl of steam (all steam quantities are expressed in barrels of water vaporized) have been injected, resulting in production of an additional 4.1 X I0 9bl of oil, or 33 percent of the oil originally in place. This corresponds to a cumulative oil-stearn rario of 0.37 bbllbbl. It appears that the steam preferentially moves r updip while liquids are produced mainly from downdip wells observations indicate that tile steam flows through only the upper part of the formation. The lateral steam distribution in the pattern is satisfacrory since several prodriction wells hardly reacted and, hence, cori tributcd little to the oil production. Production performance and results from material balance calcutlations agree satisfactorily with the results of large-,scale laboratory experiments. On the basis of these experirmental results the .steam drive, together with a cold water follow-up. is expected to bring ultimate recovery to a value of crt leas: 50 percent of the oil originally in place. No serious production problems have been encountered. However, due to mechanical fuilure, two old prodriction wells and one injection well had to be replaced. An extension of the. steam drive in this area is under connstruction. Introduction The Schoonebeek oil field, discovered in 1943 and developed after World War 11, is situated in the eastern part of the Netherlands. The main oil reservoir in this field is the Valanginian sand. A completely sealing fault divides this reservoir into two areas (Fig. 1): the southwestern part of the sand body where primary production is ob- tained by means of a solution-gas drive, and the remain. der where edge-water drive is the production mechanism. In the greater part of the field the reservoir consists of a single, unconsolidated sand body. The net thickness ranges from 30 to 100 ft and the top is between 2,400 and 2,800 ft below sea level. Formation permeability varies from approximately 10,000 md at the top to values of the order of 1,000 md at the bottom, and porosity is about 30 percent. The reservoir contains a paraffinic oil of 25" API gravity with an in situ viscosity of 160 to 180 cp. Initial oil saturation was high (85 to 90 percent). The relatively large quantity of oil in place (more than 10&apos; bbl), and the low ultimate primary recoveries expected from this field — approximately 15 percent stock-tank oil initially in place (STOIIP) for the water-drive area and 5 percent STOIIP for the solution-gas drive area — clearly indicate ample scope for secondary recovery. Because ies-ervoir and crude characteristics made this field suitable for thermal secondary recovery, a hot-water drive project was started in the water-drive area about 10 years ago. A few years later a steam drive and an in situ combustion project were started in the solution-gas drive area. This paper deals with the performance of the steam-drive project, which was started in Sept., 1960, and which is still in operation. Design of Steam-Drive Project, An experimental investigation of the steam-drive process carried out by schenk in 19561 indicated that under schoonebeek conditions steam injection could be an attractive secondary recovery method. the findings and encouraging results of a pilot test in the Mene Grande field in venezuela,i led to the design of a steam-drive project in the schoonebeek field, Pruject Site and Pattern In 1958 the reservoir pressure in the solution-gas drive area had decreased to about 120 psi, and oil production rates of wells in this area had dropped to 7 to 10 B/D. The cumulative primary production was about 4 percent STOIIP, leaving an oil saturation of approximately 85 percent. In view of the large amount of oil left behind in the reservoir, the solution-gas drive area was selected for the planned steam-drive project. The area in the vicinity of Well S1 3 (Fig. 2) was considered to be suitable since it is at least partly isolated from the rest of the field by faults and the sand is relatively thick (about 80 ft).

Jan 1, 1969

By AIME AIME

THIS journal is fully indexed-every issue, as soon as published-in a set of card?, which thus brings ready to your hand any article on any subject in this journal or in any one of 1700 other journals in all languages. This Engineering Index Service, instituted in January, 1928, is to be found in the Public Libraries of Newark, Cleveland, Bridgeport, Baltimore and the John Crerar Library, Chicago. Engineers in any field who live or work in New Jersey will find this mammoth index to the latest engineering literature in the Public Library of Newark, N. J.

Jan 1, 1929

By John D. Meahin

THE use of digital methods for generating crystallo-graphic data is well-established and many programs are now available. Transmission electron microscopy usually requires a knowledge of the electron diffraction pattern which is obtained by plotting a planar section through reciprocal space. With cubic symmetry these sections are very easily produced, but with hexagonal and lower symmetry systems considerably more labor is involved. Johari and Buchanan1 have written a Fortran program for generating standard projections and along similar lines we have produced a short but completely general program for generating any section through reciprocal space. The required inputs are the lattice parameters and angles for the real crystal. The Miller indices of the direction [U, V, W] parallel to the electron beam are then specified and the program will generate the Miller indices of the plane normals perpendicular to [U, V,, W] up to some specified integer. A subroutine can be inserted to test for forbidden reflections if desired. We have used such routines for fct and hcp crystals. As each permitted index is generated it is printed or punched out and no storage arrays are utilized in the computer. The normal diffraction pattern corresponds to the zero-order Laue zone, but with thin crystals or crystals of large lattice parameters the higher-order Laue zones may contribute to the diffraction pattern. Accordingly the program will generate successive Laue zones and project them onto the zero-order zone. The output of the program first lists the zone axis [C, V, W] and the Laue zone, and then gives a list of permitted reflections and the corresponding XP and YP coordinates of the reciprocal lattice point in angstroms-&apos;. In addition, ZP, the perpendicular distance of the reciprocal lattice point from the (U, V, Ur) plane in reciprocal space is given, as is the reciprocal interplanar spacing. In the case of the zero-order Laue zone ZP is zero. A diffraction spot from the higher-order Laue zones will be very slightly displaced from the computed coordinates as its position in an actual pattern is given by projection along the diffracted beam2 and not along [u, V, w]. For any given electron wavelength this correction could be readily incorporated into the program, but as it only amounts to -1 pct it was decided to leave the program in its most general form, i.e ., a computation of points

Jan 1, 1970

By G. C. Wallick, W. R. Foster, J. G. Savins

A comprehensive review of the salient features of the differentiation method of rheological analysis in Poiseuille flow from its inception circa 1928 is presented. Here no initial assumptions regarding the nature of the function relating rheological parameters to observed kinematical and dynamical parameters are required in the data-analysis process. In contrast, the integration method involves interpreting flow properties in terms of a particular ideal model. It is shown that, although both methods represent modes of solution of the same integral equation, being relatively bias-free, the differentiation method offers a more discriminating procedure for rheological analysis. The application to problems involving plane Poiseuille flow is also described. INTRODUCTION In most instances, the approach to the problem of interpreting the rheological properties of various compositions as they are affected by changes in chemical or physical environment, assaying the characteristics of a particular constituent of a suspension, analyzing flow behavior in terms of interactions between components in a system, to cite but a few examples, has been in terms of what Hersey1 terms the integration method. Briefly, it consists of interpreting flow properties in terms of a particular ideal model. The usual practice of the integration method is to choose a model with a minimum number of parameters because, other things being equal, it is desirable to use the simplest model which will describe the behavior of a real material and yet be mathematically tractable for the requirements of data analysis. This expression is then substituted into an equation which relates observed kinematical and dynamical quantities, such as volume flux Q and pressure gradient ], and angular velocity and torque T, in a capillary and concentric cylinder apparatus, respectively. The rheological parameters appear on integrating, in an expression relating the pairs of observable quantities such as those just given. In many instances a particular model provides a good representation of rheological behavior over a reasonable range of compositional and environmental changes. Just as often, however, it is obvious that the interpretation of rheological changes by the integration method is not providing realistic information about changes in flow behavior. A more general method of interpreting rheological data for a given material is to make no initial assumptions regarding the nature of the function relating rheological parameters to observed kinematical and dynamical quantities, e.g., flow rate and pressure drop in capillary flow or angular velocity and torque in a rotational viscometer. This general method Hersey1 terms the differentia-ation method. Instead of integrating, one differentiates the integral equation with respect to one of the limits, i.e., one of the boundary conditions; the resulting expression contains the same observable quantities just given, their derivatives, and the rheological function evaluated at that boundary. By obtaining these derivatives from experimental data, graphically or by a computer routine, they can be substituted into the differential equation and a graphical form of the function derived. THEORY OF THE DIFFERENTIATION METHOD FOR POISEUILLE-TYPE FLOWS In this introductory paper, two flow cases which are important in viscometry are considered (one for the first time) from the differentiation method of analysis, flow in a cylindrical tube and flow between fixed parallel surfaces of infinite extent, the basic integral equations being formulated in a manner analogous to the way they originally appeared in the literature. In addition, the following ideal conditions will be assumed: (1) an absence of anomalous wall effects, (2) isotropic behavior everywhere, and (3) steady laminar flow conditions. Before proceeding it would seem appropriate to preface the analysis of these flow geometries with the comment that the basic philosophy of the differentiation method could be said to stem directly from the efforts of Herzog and weissenberg2 to indicate systematically the various ways of using

By J. P. G. Farr, R. Brownsword

THE role of solute segregation in the formation of cellular solidification substructures in tin and its dilute alloys is well-established, see, e.g., Ref. 1. Segregation has been shown to persist during cooling, enabling solidification structures to be studied from sections taken at some distance behind the interface. In the present work, a single crystal of commercial nickel, 99.965 pct, was examined in this way. The crystal was cut from the center of a rod given a single pass in an electron beam floating zone melter. Polished sections of a nickel specimen taken normal to the growth direction showed a very fine precipitate phase, the distribution of which varied over the section. The identification of the phase proved difficult because of the small amount present and the small particle size, about 1 p: but it was shown by probe microanalysis to contain only nickel and oxygen in detectable concentrations and was probably nickel oxide, NiO. Bulk analysis of the material before melting showed there to be only 3 to 4 ppm of oxygen present, thus demonstrating a very considerable segregation concentration effect. In some areas of the section the precipitate formed a discontinuous hexagonal network suggesting decoration of the cellular boundaries known to be present in the sample2 whereas in a restricted region the precipitate formed small clusters. Occasionally it could be seen that the clusters were at the intersections of an hexagonal network of cellular dimension. It was suggested3 that this was the result of enhanced segregation to the cell boundary intersections whereas general cell boundary segregation was insufficient to give a precipitate. Enhanced nodal segregation has since been demonstrated in a number of systems.1, 4-8 The development of a suitable electrolytic etching technique (perchloric acid 20 pct v/v; ethyl alcohol 70 pct; glycerol 10 pct; current below electropolishing plateau; 1 to 2 sec etching) suggested the association of the phase with regions of solute segregation (where ko < 1); in these regions anodic attack produced grooves or depressions. In a study of the variation of solidification substructures with degree of constitutional supercooling, Biloni et a1.&apos; appear to have used standard growth conditions and varied the solute concentration. They were able to produce in a series of individual tin crystals examples of substructure ranging from planar interface through various cellular structures to den- Fig. 1—Electroetched section taken normal to the rod axis; the center of the rod lies to the left and the periphery to the right of the micrograph. The variation of structure across the section is evident. Magnification 60 times. drites. It was possible in the present nickel crystal to observe a continuous range of substructures varying with degree of supercooling across a single section as shown in Fig. 1. Growth rate, 13 mm per min, and temperature gradient were essentially constant; the variation in structure is thought to be due to a radial gradient in solute concentration ahead of the solid interface. The liquid at the interface is likely to have been richer in solute toward the periphery of the zone, the result of curvature of this interface. The type of substructure was seen to vary with increasing constitutional supercooling as follows: a) region free of precipitate. top left, Fig. 1: 6) region of nodal precipitates which became arranged in hexagons on passing from the center of the rod: c) irregular hexagonal cells with incomplete boundary precipitation; d) regular hexagonal cells of decreasing size with complete boundary precipitation. Fig. 2 shows the transition from stage 6 and Fig. 3 shows the structure in stage d. Within stage 0, the range of conditions over which irregularly positioned nodes occur appears to be small and the nodes are soon recognizable as taking up positions at the intersections of an hexagonal network as the supercooling increases.

Jan 1, 1970

By Robert M. Grogan, Gill Montgomery

Fluorspar, the commercial name for fluorite, is a mineral composed of calcium fluoride, CaF,. Its valuable properties are due to its content of fluorine, and it is the principal commercial source of that element. The name is derived from the Latin word "fluere," to flow, because the mineral has a low melting point and is used in metallurgy as a flux. Cryolite is a sodium aluminum fluoride, Na,AlF,. It is a rare mineral which has been found in commercial quantities in only one place in the world, Greenland. Small amounts of it are shipped from stock in that country, and its place in industry has been taken over almost completely by synthetic cryolite. Because of the relative unimportance of cryolite, discussion of it has been relegated to a short section at the end of this chapter, which is principally concerned with fluorspar. History Fluorspar was used for ornamental purposes by the Greeks and Romans, who fashioned such things as vases, drinking cups, and table tops from it. Various peoples including the Chinese and the American Indians carved ornaments and figurines from large crystals. Its usefulness as a flux was known to Agricola (1564), who wrote about it in 1546. Mining began in England about 1775 and at various places in the United States during the period 1820 to 1840. Production became substantial following the development and widespread adoption of the basic open hearth method of making steel, in which fluorspar is used as a flux. After that, production and usage were stimulated by growth in the steel, aluminum, chemical, and ceramic industries and were accelerated by World Wars I and II. Fluorocarbons entered the picture in 193 1 and the use of anhydrous hydrogen fluoride (HF) as a catalyst in the manufacture of alkylate for high octane fuel blends began in 1942. The development of the froth flotation process in the late 1920s, a differential flotation scheme for separating fluorspar from galena, sphalerite, and common gangue minerals in the 1930s, and the application of heavy-media concentrating methods to the treatment of low grade ores in the 1940s were outstanding technological contributions that enabled increased production of fluorspar concentrates. In recent years the development of pelletizing and briquetting processes for making flotation concentrates into gravel-size particles for use in steel furnaces and the development of more efficient and selective flotation schemes for treating crude ores containing abundant dolomite and barite have been major improvements in the industry.

Jan 1, 1975

By CHARLES M. SCHWAB

THE ENGINEERS have placed this great country of ours in a preeminent position with everything pertaining to manufacture, metallurgy, and the kindred arts. We are second to none in the world. We have a country which, another speaker has said, God has endowed with such riches in coal and natural resources as no other country in the world. But rich as these are, there is one thing greater; the sturdy character, energy, and integrity of its people, which will make these great resources an influence in the world&apos;s developments. Great as are these resources and the energy and integrity of our people, there is one problem of our .engineering, which I term human engineering, that is of far more importance than the creation of machines and methods, with which you have been so successful in the past. Of what value is the skillfully devised machinery, the complex process, unless manned and operated by people whose heart and soul are in sympathy with the work they are doing and who have before them the giving of a complete day&apos;s work for a day&apos;s pay?

Jan 1, 1920

By N. F. Fiore, M. F. McGuire

THIS communication describes a series of experiments in which dislocation etch pitting was used to ascertain the depth of damage in crystals which were mechanically polished or which were cut with either a commercial metallographic cut-off wheel,* a com- All specimens were cut from single crystals of American Smelting and Refining Co. 99.999+ pct pure copper which were grown from the melt by the Bridge-man technique. The test specimens were disks, with faces being (111) planes and the disk axis a (111) direction. The disks were annealed in a vacuum of 10-5 Torr for 24 hr at 950°C prior to cutting or polishing and were given a light electropolishing in an ortho-phosphoric acid bath before etch pitting. Both Youngs1 and Livingston&apos;s2 reagents were used for etch pitting and the reagents gave identical quantitative results; however Livingston&apos;s reagent produced less staining and so all photomicrographs shown are of {111) surfaces etched with this solution. The surface of the annealed crystals showed well-defined subboundaries and a density of dislocations of about 1 X 106 per sq cm excluding those present in subboundaries, Fig. 1. The depth of cold work produced during mechanical polishing was determined after an annealed specimen was mounted in a paraffin holding block to protect it from extraneous damage. The exposed (111) surface was ground on metallographic papers and then polished on billiard cloth through 0.05-p alumina abrasive. It was necessary to remove about 0.3 mm (-0.01 in.) to obtain a structure representative of the annealed sur- face, indicating that the crystal was damaged to this depth during mechanical polishing. The cold work caused by standard cutting methods was measured in another series of tests in which cuts

Jan 1, 1967

By J. J. Ormsbee

Attempts at coal-washing have been made in the southern states during the last twenty years; but it is only within the last four or five years that the practice has become at all general. It might perhaps be claimed as one of the blessings derived from our departed " booms;" for, during their sway, the supply of coal of all qualities, good and bad, could not equal the demand; but, with the subsidence of the inflated demand, came imperative calls for fuels of better quality; and washers, previously regarded as luxuries, became necessities. Among those now in use in this section are representatives of the following types or classes: the trough washer; the jig washer; the percussive table; and those washers in which a constant upward current of water effects the separation. Without having full statistics, it is safe to say that there are in successful operation in the South more washers of the last class than of any of the others. The purpose of these notes is to present data with regard to the constructiOn, operation, and results of one of these current-washers, based mainly on the plant at No. 2 Slope, Pratt Mines, Alabama. The coal is mined from the well-known Pratt seam, having here an average thickness of 3 feet 6 inches. It has distinct cleavage-planes, and breaks in cuboidal lumps; is bright black in color, firm in structure, and air-slacks only after considerable exposure. It burns freely, leaving a gray or buff-colored ash. The lump- and nut-coals are used for domestic and steampurposes (chiefly, however, for locomotive firing), and the slack for making coke. The specific gravity is 1.272. Analyses of Pratt Coal. I. 11. 111. IV. Min. Resources Authority. Phillips. McCalley. of U. s.,1892. Lupton. Fixed carbon,. . 67.90 61.600 64.30 63.82 Volatile material,.. 29.80 31.480 32.08 31.85 Moisture,.,...... 1.508 1.07 1.02 Ash,.... 2.30 5.416 2.08 3.31 Sulphur,. .. 0.83 0.918 0.47 0.70

Jan 1, 1896

By Charles Catlett

Probably no one has had occasion to examine an undeveloped coal property without hearing some hopeful or interested party insist that the bed will improve when opened some distance under cover. When the bed is already in good condition, the opinion is usually advanced that the same character may be expected, at least to the bounds of the hopeful individual&apos;s holdings. My attention has been called in this way to the extent to which a bed is affected by its outcrop at the surface ; and having had opportunity to examine a number of openings immediately at the surface, and also a short distance under cover, I submit some observations bearing on this question. Whatever may have been the original variations, we may assume that coal-basins presented in comparatively modern times approximately parallel beds interstratified with fire-clay, slate, sandstone, etc., as represented by Fig. 1. Under the effect of erosion, Fig. 2 would be formed. It is obvious that along the line A, B, C, in Fig. 1, the beds exist under conditions differing from those at A&apos;, B&apos;, C&apos;, or again at A", B", C", in Fig. 2, in their exposures to atmospheric agencies, pressure and erosion. The effect of the first is to decompose and soften many of the strata; of the second, when presented unequally, to cause the movement of such material as was at all plastic towards the point of least pressure ; and of the third, to remove the strata in whole or in part. It

Jan 1, 1901

By F. P. Bullen

Empirical relationships between fracture stress, orientation angle, and diameter of crystal have been determined at 77°K. Orientation ranges of markedly different behavior were found—a law of constant normal stress&apos; of value a (diameter)-1/2 for the fracture of ductile crystals, and a condition of shear stress (or strain) for more brittle crystals. The observations are not consistent with current theories. An interpretation is advanced which is also applicable to observations on the effect of prestrain at room temperature on the subsequent fracture stress at 77°K and to the effect of cyclic stressing on the cleavage strength.&apos;&apos; The law of constunt normal stress&apos; and the brittle ductile transition are also explained. The interpretation is more consistent with the initiation of cracks by intersecting dislocations than with theories based on stress -concentration by dislocation arrays. ZINC single crystals are particularly suited to the study of cleavage because fracture occurs on the basal plane over a wide range of crystal orientations. Analysis of the conditions of stress and strain at fracture in crystals of different orientations should indicate which parameters control the cleavage process. Unfortunately, controversy has arisen over the correct empirical relationship between tensile fracture stress and orientation. Schmid&apos;s observations1,2 favored a &apos;law of constant normal stress&apos;, as observed in other materials.2 For zinc, however, the observed values are far below the theoretical strength and cannot represent the true limit of cohesion between neighboring atomic planes. Hence, the interpretation of such a &apos;law&apos; is not straightforward. Deruyttere and Greenough3,4 found a complex variation between tensile fracture stress and orientation; this variation did not agree with a &apos;law of constant normal stress&apos;. Two theories have been advanced to account for their observations: a) the propagation of cracks from low-angle boundaries,5 and b) the release of energy from piled-up dislocations during crack-propagation.4 The present work resolves the apparent discrepancy between the observations and shows that neither of the above theories are applicable to the tensile fracture of zinc single crystals. A phenomenological explanation, along the lines suggested by Gilman,&apos; is advanced and successfully applied to previously unexplained effects. EXPERIMENTAL DETAILS &apos;Crown Special&apos; redistilled zinc was used, except for one comparison series op tests using &apos;Tadanac&apos; electrolytic zinc. Crystals of 1 mm diam, subsequently called &apos;1 mm crystals&apos;, were grown from the melt in vacuo in precision-bore Pyrex tubes internally coated with graphite. Several specimens 1 in. long were cut from each crystal and chemically polished. Jigs were used to minimize handling strains, and crystals were mounted in the Polanyi machine the day prior to testing to allow recovery from any such strains. One-mm crystals were chemically polished for long periods to obtain 0.1 mm (approx) crystals. One-mm crystals were cemented into miniature gimbals by &apos;Araldite&apos; casting resin. The Appendix gives the reasons for using gimbals and the results obtained by other methods. More complete details of all techniques are given elsewhere.7 The symbols and terminology used are as follows: X = orientation angle (angle between tensile axis and line of greatest slope in the basal plane). T = tensile stress (on true cross-section) S,N = shear and normal stress (components of T with respect to the basal plane) ? = shear strain D = crystal diameter. The subscript &apos;f&apos; will be used to denote values at fracture. PART I-ANNEALED CRYSTALS EXPERIMENTAL OBSERVATIONS One-mm crystals were used to establish the variation of fracture stress at 77°K with orientation at fracture (Xf), Fig. 1. For 18 deg = Xf = 55 deg, a &apos;law of constant normal stress&apos; was observed. For Xf > 55 deg, the fracture condition approximated to a constant shear stress. At Xf< 18 deg, twinning occurred before fracture so that the results were not typical of homogeneous single crystals,4,8— such specimens will not be considered herein. The dependences of fracture stress upon Xf were of similar type for 6 mm,* 1 mm, and 0.1 mm crystals,

Jan 1, 1963

By Alfred R. Powell

LATE in 1944 a group of petroleum and coal technologists was organized in Wash¬ington under the sponsorship of the Petroleum Administration for War and the U. S. Bureau of Mines. This group, known as the Technical Oil Mission, was placed under the authority of the Technical Industrial Intelligence Committee of the Joint Chiefs of Staff, which was then promoting the organization of other missions to be sent to Germany to obtain technical information regarding various industries in that country. The objective of the Technical Oil Mission was to obtain technical data on German production of synthetic oil from coal and all other commercial practices and research projects connected with the oil industry. The primary purpose was to obtain such data as were immediately essential to assist the war against Germany and Japan, with secondary emphasis on technical information that would assist American industry after the end of the war. Since oil-production facilities in Ger¬many and the occupied countries con¬trolled by Germany were the top targets for strategic bombing, the Technical Oil Mission was the first group under the Technical Industrial Intelligence Com¬mittee to enter Germany. A few members of the group flew to London in February 1945 and the majority of the remainder followed in March. In London they were joined by an equal number of British investigators and the combined, mission was then sent into Germany under the authority of the Combined Intelligence Objectives Subcommittee (CIOS). A sum¬mary of the more important information gained by this combined British and American mission is presented below. GERMAN OIL PRODUCTION The oil available to Germany, both natural and synthetic, and including pro¬duction from occupied countries, reached a peak in late 1943 and early 1944. Pro¬duction at this time was at the rate of 1,200,000 metric tons per month, equiva¬lent to i00,000,000 bbl. per year, or about 7 per cent of the wartime production in the United States. Of this production, 50 per cent was crude oil from Romania and Hungary, 12 per cent was crude oil from Germany itself, including Austria, 9 per cent com¬prised coal-carbonization products, that is, tar and light oil, and only the remaining 29 per cent was synthetic liquid fuel made from coal or tar. Synthetic liquid fuel made in Germany was equivalent therefore to less than 2 per cent of war¬time production of crude oil in the United States. The success of the strategic bombing campaign against German oil-production facilities is demonstrated by the fact that by September 1944 the Ploesti fields of Romania and much of the syn¬thetic oil production had been eliminated, so that the amount of oil available to the German war machine was only 25 per cent of the peak quantity mentioned above. By early 1945, when the combined British and American oil mission was entering

Jan 1, 1946

By J. B. Conway

Stress-vuptuve data for several of- the refractory metals are frequently found to yield a linear relationship between the Larson-Miller parameter and the logarithm of the applied stress. In such cases linear stress-rupture isotherms result with slopes bearing a definite relationship to the temperature. It also follows that the stress to produce rupture in a certain period of time will be linear in temperature. Data for several refractory metals have been reviewed and excellent linearity is shown in this type of isochronal plot. In addition, the af ore - mentioned lineavity leads to a linear relation between the log of the stress to produce rupture in a certain time and the homologous temperature. This has been illustrated for the Group VI-A metals, tungsten and molybdenum. EXTENSIVE use has been made of the Larson-Miller&apos; parameter in the interpolation and extrapolation of stress-rupture and creep data. In those cases where this particular parametric approach is applicable a convenient and fairly straightforward procedure is made available for the correlation of experimental stress-rupture data. It is quite common to employ this parameter in the form of a master rupture plot in which the parameter, T(C + log tr), is expressed as a function of log stress. In many cases this functional relationship in log stress is linear within acceptable accuracy and hence the following relation results: where P is the parameter, C is the Larson-Miller constant, T is the absolute temperature, t~ is the rupture time, a is the stress, and a and b are constants. Examples of such a relationship are contained in the work of Green, Smith, and 01son2 dealing with high-temperature rupture behavior of molybdenum and in the work of Green&apos; dealing with the high-temperature behavior of tungsten. In addition, pugh4 has shown a similar linearity for some fairly low-temperature data for molybdenum. It can be shown that when the relationship in Eq. [I] is exhibited certain generalizations can be made concerning the form of the stress-rupture isotherms. For example, rearranging yields: For a given material (constant C) at a given temperature the first term on the right-hand side of Eq. [2] is a constant and hence this equation defines a straight line when log stress is plotted as a function of log-rupture time. This is recognized as the standard form usually employed in this type of data presentation. Such linearity then suggests the linear form of the Larson-Miller parameter. Or, in other words, the linear parametric relationship in Eq. [2] results only when the stress-rupture data are linear on a log-log plot of stress vs rupture time. Another interesting observation can be made in regard to Eq. [2]. It can be noted that the slope of the stress-rupture isotherms is given by - T/b and hence a direct calculation of the constant b is available. It also follows that since the value of b is the same for all temperatures the slopes of the various isotherms on the log-log stress-rupture plot cannot be the same. Indeed, the existence of the relationship in Eq. [2] precludes a system of parallel lines on this common stress-rupture plot. As a matter of fact it further specifies that in addition to being nonparallel the slope of these isotherms must decrease (i.e., become more negative) with increasing temperature. Such a condition is indeed found to exist in the case of the stress-rupture data reported for molybdenum.&apos; As a corollary to the above, it may be stated that stress-rupture data which do not lead to a linear log-log stress-rupture plot or whose isotherms do not exhibit a decrease in slope as the temperature increases will not yield the linear relationship of Eq. [I]. Applying Eq. [2] to two different temperatures and solving for C yields: Eq. [3] affords a simple and rapid method for calculating the Larson-Miller constant from the log-log stress-rupture plot. The slope of a given linear isotherm is measured and the value of "b" calculated based on Eq. [2] as: slope = - -Tb Then at an abscissa value of 1.0 hr (making log tr in Eq. [3] equal to zero) read the stress corresponding to rupture for two different temperatures. Substitution in [3] yields: A value of the Larson-Miller constant can thus be calculated from a few simple mathematical procedures employing data read directly from the log-log plot of the stress-rupture data. Of course, it is not to be overlooked that the above reasoning has been based on the linear relationship of Eq. [I] being applicable. However, if as mentioned above the log-log plot is

Jan 1, 1967

By N. Jaffee, J. E. Dorn

An activation energy of 27,400 5 1000 cal per mole was obtained for the creep of poly crystaLline aluminum over the temperature range of 273° to 350°K, at strains varying from 0.003 to 0.230. Stresses varied fronz 2250 to 6000 psi, strain rates from 0.1145 x 10-5 to 29.5 x 10~s min.-1. A strain temperature-compensated time correlatzon was oblained indicating that the structure was depedent solely upon the strain at a given stress; X-ray diffraction analyses and tensile tests on precrept specimens verified this. PREVIOUS investigations1 have revealed that the apparent activation energies for creep of high-purity polycrystalline aluminum are insensitive to the applied stress, strain, and strain rate. On the other hand, the apparent activation energy is dependent on the temperature1,2 as shown by the data reproduced in Fig. 1. Each plateau of this curve is associated with a unique rate-controlling dislocation mechanism for thermally activated creep. It is now very well-established that over the high-temperature range, where the activation energy is about 35,500 cal per mole, the creep rate is controlled by the dislocation climb mechanism. 3 Over the intermediate range of temperatures, from about 260° to 370°K, another unique activation energy, namely 28,000 cal per mole, is obtained. Current evidence strongly supports the contention that cross slip is the rate controlling mechanism for creep in this case: 1) Crystal recovery can occur by a number of mechanisms prominent among which are climb and cross slip. Astrom,4 using the Borelius micro-calorimeter, reported rapid crystal recovery of cold-worked polycrystalline A1 at 340° to 370°K giving an activation energy of 28,000 cal per mole and additional recovery at 455° to 478°K giving an activation energy of 3 6,000 cal per mole. Whereas the latter recovery process was clearly associated with the dislocation climb mechanism, the former, 28,000 cal per mole process could have arisen as a result of the cross-slip mechanism. 2) Single crystals of high-purity A1 favorably oriented for octahedral glide exhibit an activation energy for creep of about 3400 cal per mole over the range from 0° to 400°K and that of about 28,O:O cal per mole over the range from 600° to 775°K . Whereas the lower activation energy process is accompanied by the development of sharp slip-band traces, the 28,000 cal per mole process was uniquely characterized by extensive cross slip. 3) Theoretical calculations by Seeger and schoeck6 suggest an apparent activation energy for cross slip in A1 of about 24,000 cal per mole and another theoretical estimate by Friedel 7 gives the observed 28,000 cal per mole as the theoretical activation energy. It is therefore consistent with this evidence to, at least tentatively, ascribe the 28,000 cal per mole creep process in A1 to the operation of cross slip as the rate controlling mechanism. Although creep has been rather well-explored in the dislocation climb range, very little, excepting perhaps the activation energy, is known about creep in the cross slip range. This investigation was undertaken, therefore, to reconfirm the activation energy for creep in polycrystalline A1 in the intermediate temperature range and to study the strain-time relationship for creep at a constant stress in the cross slip region. EXPERIMENTAL PROCEDURE AND TECHNIQUE The three types of high-purity A1 alloy specimens described in Table I were used in this investigation. Specimens were milled from 0.100 in. thick cold-rolled sheets with their tensile axes in the rolling direction following which they were given a recrys-tallization and grain growth heat treatment at temperatures well above those which were subsequently employed in the creep tests.

Jan 1, 1962