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By J. D. Miller, P. J. McDonough, H. Q. Portillo

Previous investigations have demonstrated the catalytic effect of silver additions in the ferric sulfate leaching of chalcopyrite [ ] The enhanced rate of leaching was found to be due to the formation of an intermediate Ag S film which forms on the Cures2 surface by an exchange reaction Under these conditions, unlike the uncatalysed ferric sulfate leach, the elemental sulfur forms a nonprotective reaction product on the Ag S crystallites As a result, the rate appears to become limited by an intermediate electrochemical reaction in {he Ag2S film rather than by transport through the elemental sulfur reaction product [ ] The reaction rate was found to have a complex dependence on the Ag+, Fe++ and Fe+3 concentrations, but independent of the Cu concentration Electrochemical measurements with a Ag,S-coated chalcopyrite electrode provide further information regarding the nature of the reaction mechanism The kinetics of the rate limiting, intermediate electrochemical reaction are analyzed in terms of the Butler-Volmer equation

Jan 1, 1981

By L. P. Teas

Although 1927 in the Arkansas-Louisiana territory will probably pass into history as a year of small profits and little new production, nevcrtheless during this period two large gas fields were developed; two new oil fields were discovered, and two new oil horizons, hitherto of minor annual production Fig. 1.—Production of North louisiana and ARkansas by fields, for 1926 and 1927. (Upper blocks represent 1926 production; lower blocks, 1927 production ) importance, were developed. In spite of the "hard times" some of the leading supply houses did more business this year in this district than in any year since 1920.

Jan 1, 1928

By G. G. Gunther, C. L. Boeke

THE zinc deleading processes at the Parral and Santa Barbara mills are described separately to provide a basis for comparison. Although the two procedures are fundamentally alike, there are some differences in application to meet specific conditions. The Asarco mill at Parral in the State of Chihuahua is a flotation plant treating 1450 metric tons per day of complex sulphide copper-lead-zinc ores. In general, the procedure used for selective separation of the minerals into a copper, a lead, and a zinc concentrate follows the usual practice. First, a bulk copper-lead concentrate is floated and then separated into a final copper and a final lead concentrate by the sulphurous acid process. A small tonnage of high grade gravity lead concentrate is tabled from the bulk copper-lead cleaner tailing before it is reground so as to avoid undesirable over-grinding and sliming of this portion of the lead mineral. Next, a zinc concentrate is floated from the lead rougher tailing and, as described later, is separated into a final lead product and a final zinc concentrate. Finally, the zinc rougher tailing receives a strong scavenger float to remove all recoverable middling values for regrinding and return to the flotation circuits. The slime is separated from the scavenger flotation product, and only the sand portion goes to the regrind section. The minerals in the separated slime are extremely resistant to all methods of selective separation and pose one of the major problems awaiting solution. Nevertheless, the slime shows a profit when mixed with either the lead or the zinc concentrate, except when metal prices are very low, so it is accepted as a final product for lack of a more profitable method of handling it. In contrast, the minerals in the reground sands of the

Jan 1, 1953

By S. R. B. Cooke, R. O. Huch, C. S. Chang

IN the flotation of iron ores laurylamine derivatives have been used for considerable time.12 To effect satisfactory separation of the gangue, predominantly silica, from the iron oxide minerals, the addition of specific depressants for the iron oxides has been found necessary. Starches and starch products have been used for this purpose. 3 There is, however, very little published information on the effects of these materials and other variables on this process. In some cases it has been found that prior acid scrubbing and desliming are essential, 4 and depending upon the efficiency of the subsequent washing step, there will be accompanying changes in pH. It was the object of this investigation to test and observe the effects of the above factor as well as to examine and compare the action of various starches and starch products.

Jan 12, 1953

By G. W. Jones

THIS paper describes experiments in which eight test samples of gelatin dynamite were fired in three different types of apparatus and the quantity and composition of the gaseous products of detonation determined. The special dynamites were so prepared that the oxygen balance of the samples varied from -35.0 to +6.0 g. per 100 g. of explosive, including the wrapper. By means of this graded series of explosives, the relation between oxygen balance and gaseous products of detonation could be studied explicitly. The effect of varying oxygen balance on explosive strength has-been discussed in another paper.1 The apparatus employed in the work described in the present paper included (1) the Bichel gage, a steel bomb of 15-1 volume; (2) the Crawshaw-Jones confined detonation apparatus, a steel cannon from which the explosive is fired into a pipe of 904 volume; and (3) the Hercules tank, an apparatus in which the explosive is confined in a quartz block which is placed in a steel tank of about 4500-1. volume. A full description of the apparatus is given later. VARIABLES AFFECTING COMPOSITION OF DETONATION PRODUCTS The character of the detonation products of commercial explosives is governed in part by the same factors that affect the combustion products from explosive mixtures of air with gases or vapors. In either case, combustible materials-namely, carbon, hydrogen, and sometimes sulfur-are present and combined variously. In an exploding gas mixture the combustibles are oxidized by oxygen in the admixed air, whereas with explosives the necessary oxygen is provided by oxygen-carrying materials in the explosive ingredients.

Jan 1, 1928

By B. M. Andreas

PRIOR to 1934 all haulage of ore and stripping on the Mesabi Range was by rail. Early rail systems had small narrow-gage locomotives with correspondingly small dump cars. These trains were replaced with larger standard gage rail systems powered by steam locomotives ranging up to 224 tons in weight, which have in turn been replaced by diesel electric locomotives. Along with this development cars have been increased to 30-cu yd capacity. Improvement of cars includes alloy steel construction for lower over-all weight and use of roller bearings to decrease rolling resistance. Despite all of these developments, the total material hauled by rail on the Mesabi Range has decreased every year. Yet, this is no reason to believe that rail haulage is becoming obsolete. Its adaptation to small mine operation has become impractical, but in large mines where normal railroad grades are possible or where hauls to plants or dumps are long, rail haulage is still one of the most economical methods of transporting large quantities of material.

Jan 1, 1954

By J. H. Bucher

The effect oj strengthening by the precipitation of CbC on the toughness offerrilic steel (0.11 pct C, 0.74 pct Mn, 0.02 pct Cb) was stlrdierl. A g-veater degree of pvecij~itatiotz strengthning is ohtaznable by aging the so11ution-treated steel rtt velaticely Low temperature was (1050" to 1l0O3F) than at higher temperatures (I150" to 1200°F). Tlzis ),eslrlts because a finer dispersion of CbC is obtained. However, the ductile-brittle transition te~ripertltlo.e is raised approximately tlzjeee tirues as IFLIIC~ perv a given yield stress increase) by aging in the lower tempareture range, as opposer1 to the Irigher temperaturee range. This is proposed to result pl-iir~avily because different precipitation distributions ar-e associated with the different aging -treaments. For tile steel aged at 1050" and 1100 F, heavy: precipitation on disloccctions occurs resulting in a high degree of rlislocution pinningh tl~us lowevirzg- the toilguiess. in tll c(.rise of the steel aged at 1150 'a?zd 1300"F, Pvecipitatiol~ is irzove g-enerally distributed throughout the matrix rather limn preferentially on dislocations.; and Ike detlsitj, oj mobile dislocations is not sttyong-ly affected. THE most effective means of strengthening hot-rolled ferritic steels are grain refinement and precipitation hardening. It is well-known that grain refinement increases both the strength and the toughness. However, the upper limit of yield strength obtainable by grain refinement alone is about 60,000 psi,'12 i.e., without the formation of acicular structures of lower toughness. The most economical means of obtaining higher strengths is the addition of small amounts of elements such as columbium, vanadium, and titanium which form carbonitrides. These precipitates are very effective in increasing the strength, but the ductile-brittle transition temperature is is Although it is agreed upon that precipitation decreases the toughness, there has been little effort to isolate the causative aspects of embrittlement. The purposes of this research are to assess quantitatively the embrittlement associated with different precipitate distributions and morphologies, and to correlate the degree of the embrittlement with the microstruc-ture. In this manner, a more fundamental insight into the mechanism of embrittlement may be gained. The steel selected for this purpose was a low-carbon, columbium-bearing steel which, after solution treatment, was aged in various time-temperature cycles while attempting to hold all other microstructural variables constant. MATERIALS AND PROCEDURE The composition of the steel used in this investigation is given in Table I. Starting with commercially hot-rolled material 0.074 and 0.280 in. thick, tensile blanks were cut from the thinner material and sub-size Charpy blanks from the thicker stock. The steel had been rolled using a low finishing temperature and rapid cooling after hot rolling to produce grain refinement. Also, chemical-extraction analysis and electron-microscopic examination revealed that the cooling was rapid enough to suppress any significant precipitation of CbC. Therefore, the as-rolled steel is essentially in the solution-treated condition in terms of the precipitation reaction, and it was used as the base material in this investigation. The room-temperature tensile properties of the as-rolled steel aged at 1100", 1150", and 1200°F for various time intervals were determined, see Table 11. The ductile-brittle transition behavior was studied for smooth and notched tensile specimens, and longitudinal half-size (0.200 in. thick) Charpy V notch specimens aged at 1100" and 1150°F for various times, also Table 11. In addition, tensile specimens aged for single times at 1050" and 1200°F were evaluated with respect to their ductile-brittle transition. Only one 1050°F treatment was used because of the extremely slow kinetics of precipitation at this temperature and because no significant difference between 1100°F aging was observed. Only one treatment at 1200°F was used because aging at this temperature alters the shape of the grain boundary cementite particles present in this steel and complicates analysis. The design of the tensile specimens is given in Fig.1.

Jan 1, 1968

By J. Visman

FOR more than 25 years evaluations of coal cleaning units have appeared in many publications, and during this time considerable progress has been made in developing the theory and techniques of calculating washery results. A variety of characteristics have been defined over the years, many receiving general recognition during the first post-war Coal Preparation Conference in Paris in 1950. Coal preparation has become a science, and the approach to preparation problems is being revolutionized. Formerly, for example, if a coal operator wanted to know the performance of a given cleaning unit for a particular grade of his run-of-mine, he either shipped a carload to the manufacturer for a test run or relied on a report of a test carried out on a coal similar to the one he intended to clean. In modern practice the expensive, time-consuming test work generally can be avoided if the washability curves of the coal in question and the error curve of the cleaner are known. Normally a guarantee can be given on the strength of this information. General acceptance of modern standards has thus reduced the need for pilot-scale models of existing types of coal cleaners. Needless to say, the method requires exhaustive and accurate information on the cleaning unit and on all the additional circumstances affecting its results, in- formation that ultimately can be secured only from actual tests made in the laboratory or in the washery.

Jan 10, 1954

By S. R. Dunbas, D. C. Jillson, E. A. Anderson

THE present work was undertaken to furnish information, lacking in the literature, on the deformation mechanisms active in pure titanium at room temperature. Since it was started, Rosi, Dube, and Alexander' have indicated that slip can occur in coarse-grained (2 to 6 mm diameter) titanium on the {1010} and {1011} planes and twinning can take place on the {1072}, (1122) and (1151) planes. Liu and Steinberg,' working with titanium flakes produced by fused salt electrolysis, found evidence of twinning on the {1032$, {1121), {1122}, (1123}, and (1154) planes. The crystals used in the present work were substantially longer (up to nearly 2 in. in length) and possibly purer. Production of Large Crystals It was the purpose of this part of the work to provide single crystal or large grain specimens for use in the deformation studies rather than to study the mechanism of crystal growth. Accordingly, all further exploratory studies on methods were abandoned when it was found that cold-rolled bars sealed in vacuo in individual Vycor tubes and given three or more cycles of 4 hr at 1200°C and three to five days at 850°C, gave large grains. Eighteen specimens about 0.2 in. square x 2 in. long yielded 33 useful grains, ranging from Va in. to nearly 2 in. in length, with an agreeably wide range of orientations, Fig. l. The 0.25 in. thick strip from which the starting specimens were cut had been reduced 67 pct on 18 in. diameter rolls from a scalped, hot-forged (959" to 1000°C), arc-melted, iodide titanium ingot. Thc bar was at room temperature, but the rolls were at 200°C. Reductions of about 0.03 in. per pass were used. The bar was cut into four segments, each of which was rolled in a somewhat different manner. No effect on the growth of large grains was noted. The composition of the titanium, determined on turnings from the ingot scalping operations, is given in Table I. The Rockwell A hardness of the ingot was 26. The standard starting specimens, about 1/4x1/4x2 in., were milled on all four sides, hand polished on 280 and 400 mesh emery papers, etched for 3 min in a 50 HF-50 glycerine solution, rinsed, and dried in alcohol and ether just before sealing them in Vycor tubes. The average specimen weight was 7.5 g, and the tube volume was 6.5 cc. A vacuum of less than 1 micron pressure was applied. The specimen tubes were placed in an evacuated Inconel muffle to minimize the danger of collapse of the glass tubes at temperature. In practice the specimens were first heated to 1200 °C for 4 hr and then transferred fairly quickly to an 850°C furnace where they were held for three to five days. This cycle was repeated at least three times before the specimens were cooled, removed from the tubes, lightly polished and etched on one surface for examinstion. Those in which large grains had not developed were resealed in Vycor and returned to the cycling. Satisfactory specimens (about one out of every four cycled) were polished with emery paper on all four side;, then metallographically polished using ctchinz between wheels to remove distorted metal and, finally, given a very light etch to reveal the grain boundaries. This was necessary because the surface was roughened by the sublimation of titanium under high temperature vacuum conditions. Specimens were identified by TiXl numbers using supplementary letters to designate specific grains.

Jan 1, 1954

By L. L. Gray, D. W. Reed, F. Morgan

A flowMeter has been developed at Gulf Research and Development Co. and tested in the field for measuring the flow of gas in well bores. It has been used in a study of the injection capacity of different horizons in gas injection wells in Oklahoma. The flow sensitive element of the meter is a semi-conductor having a very high temperature coefficient of resistance. Advantages possessed by this meter are the result of that property and the high specific resistance of the element. The instrument possesses a sensitivity considerably higher than any reported previously. In the application described here the element is heated to a temperature considerably above ambient by an electric current, which is supplied by a voltage source at the surface. When fluid flows through the meter the rate of dissipation of heat is increased and the temperature of the element decreases. Because of the negative temperature characteristics of the resistance element such a decrease of temperature will be accompanied by an increase of resistance which, under flow conditions ordinarily found in wells, is of such a magnitude that it can be directly measured or recorded in terms of a change in voltage at the surface. In practice, rate of flow is measured in terms of the drop in voltage in the resistance element. All the metering and control apparatus remains at the surface while the thermal element is lowered into the well on a single conductor cable, consisting of an insulated wire and sheath. The meter is calibrated by passing known quantities of gas through it either at the surface or in the hole at a point immediately above the region in which gas is lost to the formation. In case calibration is made at the surface, the ambient temperature in the hole may readily be obtained by a second resistance element which is operated at a current so low that effectively no heating occurs. The instrument has been adapted to con-tinuous recording, but the velocity of the meter relative to that of the gas must be low unless corrections are made. Curves giving data obtained in actual field tests are shown' The meter can also be used to determine the distribution of flow capacity in a gas producing well. A differential form of the meter has been designed and built in which the local flow or injection capacity of the formation is obtained directly. Introduction When fluid is injected into a well in a secondary recovery or pressure-maintenance operation the question of its most effective use invariably arises. Although the core log, when available, will show the regions of good permeability and oil saturation, there is normally no assurance that the fluid actually enters the formation in zones where injection is deemed desirable. In view of the uncertainties involved in such programs, it is generally conceded that measurements of permeability for a formation in place are more significant than those obtained by the core-sampling technique. A subsurface meter has been developed at the Gulf Research and Development Co. for measuring flow of fluids at different horizons in a well bore, and field tests have been made on the instrument in Cooperation with the Tulsa Division of the Gulf Oil Corp. In this paper the meter is de-

Jan 1, 1948

By F. Morgan, L. L. Gray, D. W. Reed

A flowMeter has been developed at Gulf Research and Development Co. and tested in the field for measuring the flow of gas in well bores. It has been used in a study of the injection capacity of different horizons in gas injection wells in Oklahoma. The flow sensitive element of the meter is a semi-conductor having a very high temperature coefficient of resistance. Advantages possessed by this meter are the result of that property and the high specific resistance of the element. The instrument possesses a sensitivity considerably higher than any reported previously. In the application described here the element is heated to a temperature considerably above ambient by an electric current, which is supplied by a voltage source at the surface. When fluid flows through the meter the rate of dissipation of heat is increased and the temperature of the element decreases. Because of the negative temperature characteristics of the resistance element such a decrease of temperature will be accompanied by an increase of resistance which, under flow conditions ordinarily found in wells, is of such a magnitude that it can be directly measured or recorded in terms of a change in voltage at the surface. In practice, rate of flow is measured in terms of the drop in voltage in the resistance element. All the metering and control apparatus remains at the surface while the thermal element is lowered into the well on a single conductor cable, consisting of an insulated wire and sheath. The meter is calibrated by passing known quantities of gas through it either at the surface or in the hole at a point immediately above the region in which gas is lost to the formation. In case calibration is made at the surface, the ambient temperature in the hole may readily be obtained by a second resistance element which is operated at a current so low that effectively no heating occurs. The instrument has been adapted to con-tinuous recording, but the velocity of the meter relative to that of the gas must be low unless corrections are made. Curves giving data obtained in actual field tests are shown' The meter can also be used to determine the distribution of flow capacity in a gas producing well. A differential form of the meter has been designed and built in which the local flow or injection capacity of the formation is obtained directly. Introduction When fluid is injected into a well in a secondary recovery or pressure-maintenance operation the question of its most effective use invariably arises. Although the core log, when available, will show the regions of good permeability and oil saturation, there is normally no assurance that the fluid actually enters the formation in zones where injection is deemed desirable. In view of the uncertainties involved in such programs, it is generally conceded that measurements of permeability for a formation in place are more significant than those obtained by the core-sampling technique. A subsurface meter has been developed at the Gulf Research and Development Co. for measuring flow of fluids at different horizons in a well bore, and field tests have been made on the instrument in Cooperation with the Tulsa Division of the Gulf Oil Corp. In this paper the meter is de-

Jan 1, 1948

By S. D. Dahlgren

ORDERED G.P. zones having the cesium chloride structure were found to exist in the bcc iron-rich grains of an Fe-Au-Cu alloy that had been supersaturated with approximately equal atomic percentages of gold and copper, and aged at 400° and 350°C. Streaks and superlattice spots in electron diffraction patterns revealed the presence of the ordered zones in the aged material. The ordered Ll2 structure is commonly found for precipitates in fcc metals (e.g., Ni3A1 in nickelL7') but it is uncommon to find precipitates in bcc metals having the cesium chloride structure. The formation of the G.P. zones caused age hardening of the grains. Samples containing 3.8 at. pct each of gold and copper (with the remainder being iron) were annealed at 95@ or 1125°C in quartz capsules and were quenched by breaking the capsules under water. X-ray diffraction patterns revealed two solid solutions in the quenched samples. One solid solution was bcc and the other was fcc. The microstructure consisted of iron-rich grains of 0.3 mm diam surrounded by a yellow gold-copper-rich grain boundary network. The Au-Cu phase diagram %hows continuous solid solubility of gold and copper with ordered phases forming below 410°C. None of the ordered Au-Cu phases have the cesium chloride structure. Both Fe-Au and Fe-Cu phase diagrams3 show extended miscibility gaps and only terminal solid-solution phases. Consequently, it is reasonably certain the iron-rich grains consisted of an a-phase terminal solid solution, and the grain boundary network consisted of a gold-copper-rich terminal solid solution. Lattice parameters of the quenched solid solutions were consistent with the suggestion that the quenched phases were terminal solutions. The lattice parameter of the bcc phase (2.879A) obtained upon quenching from 950°C was higher than that (2.866A) for pure iron. The fcc phase in this sample had a lower lattice parameter than that for a 50 at. pct Au and 50 at. pci Cu solid solution, i.e., 3.866 compared to 3.877A. The lattice parameter for the 50 pct Au and 50 pct Cu solid solution was interpolated from data for Cu-Au solid solutions.4 More gold and copper were soluble in iron at 1125°C than at 950°C as indicated by a 0.012A increase in the bcc lattice parameter for a sample quenched from 1125°C. After the alloy had been quenched from 950° and 1125°C, the bcc lattice parameters were 2.879 and 2.891A1 respectively G.P. zones having the cesium chloride structure-which formed during low-temperature aging—were detected by electron diffraction and observed with electron transmission microscopy. In Fig. 1, the asymmetrical streaks parallel to ( 100) directions indicate that platelike G.P. zones had formed parallel to (100) planes of the matrix. The direction of streak asymmetry shows that the bcc unit cell of the G.P. zones was larger than the bcc cell of the matrix. The ordered cesium chloride structure is indicated by low-intensity superlattice spots at 010 positions which are nonallowed for bcc structures. The superlattice spots are streaked; therefore they are from the G.P. zones and are not caused by rel-rod effects of a thin matrix phase. The appearance and size of the zones observed in electron transmission microscopy and the appearance of the asymmetrical streaks in the electron diffraction patterns for the Fe-Au-Cu alloy were the same as those observed for a similarly treated Fe-Au alloy.' Ordered G.P. zones were detected also for an Fe-Au-Cu sample aged only at 400°C. The production of the ordered cesium chloride structure zones by low-temperature aging of super-

Jan 1, 1968

THE 135th meeting of the Institute was the largest and most enthusiastic that has ever been held, sur-passing passing in numbers attending even the notable meeting of 1920. The total registration was 1493. The technical sessions and round tables, 38 in number, were spread through four instead of three days as heretofore in order to reduce the number of conflicts, and most of the A. S. T. M. Committee meetings were held over until Friday. Even so it was necessary to schedule as many as seven simultaneous technical sessions, and there were usually at least two going at once that each wished to attend. Three special luncheons and five group dinners were held, each of which strung out into an informal meeting, and yet approximately 500 came to-gether each day at the general luncheon and over 700 attended the banquet on Wednesday night. The smok-er attracted 402, and the various social affairs under the charge of the general or the women's committees were all crowded. From 10.00 a.m. Monday to 11.00 p.m. Thursday there was one long series of meetings after which the members went home to catch up on their sleep. The comment on the meeting of a member of one of the other societies, who had occasion to be much in the building, was the markedly friendly spirit of the gathering, the large numbers who were evidently old friends and acquaintances. This does seem to set the miners off somewhat from other engineering groups. So many have shared the same blankets and beans at one time or another that the annual meeting has truly come to be a family reunion.

Jan 3, 1927

By S. F. Emmons

Introductoy.—In view of the fact that an opportunity is to be offered to the members of the Institute present to inspect the recent developments of gold-deposits in the immediate vicinity of Washington it has seemed appropriate that some preliminary description of them should be given which may facilitate that inspection. It would have been a matter of much satisfaction to me to be able to present some general description of the gold-deposits of the Appalachian system ; but I have as yet had no opportunity of personally examining any others than those of Montgomery county, and these are still in their infancy. It is, moreover, a slower and more difficult operation to make geological observations in this region than in the more northern States; for whereas in the latter region the

Jan 1, 1890

By Edward Wichers

THE purpose of this paper is to set forth the matters of principal interest in connection with work done in the past few years on the purification of the metals of the platinum group, including the study and modification of methods already in the literature and the development of new procedures. For the most part, the results will be given in summary form, reserving the publication of detailed data and directions for a forthcoming paper to be issued by the Bureau of Standards. In recent years increasing interest has been shown in the preparation of the pure platinum metals, both by those concerned with the manufacture of the metals and their alloys for scientific and industrial purposes and those who are engaged in the study of the chemical or physical properties of the elements. The purification of the metals usually has been regarded as a matter so involved and difficult as to require the attention of specialists. It is hoped that this paper will show that any of the metals can be prepared in any desired degree of purity by relatively simple straightforward chemical methods. For the most part, it is thought that the methods given are suitable for small-scale refineries as well as for the laboratory; also, that they will bring the time required for the purification of any of the metals within reasonable limits. The new procedure suggested for purifying platinum should prove to be much shorter than any methods described in the literature.

Jan 1, 1928

By G. Ansell, J. Weertman

G. Ansell and J. Weertman (Rensselaer Polytechnic Institute and Northwestern University, respectively) —The great increase in creep strength that you found in your indium-glass composites is quite striking. You ruled out a decrease in the dislocation source density as an explanation of the reduced creep rates. Could you tell in greater detail why you feel this is an inadequate explanation of the phenomenon. It appears to us that it is a reasonable one. Consider the spacing between the glass spheres in your composites. It is of the order of 10-3 cm. The spacing between dislocations in a (single-phase) annealed metal with a dislocation density of the order of 106 to 107 cm per cm3 also is of the order of 10-3 cm. Therefore it is not reasonable to expect that the arrangement of the dislocation lines is the same in the composite material as it is in pure indium. If the dislocation arrangements are different the density of the dislocation sources likewise will be different. Another way of saying the same thing is the following. The presence of the glass spheres reduces one of the dimensions of the metal phase to 10-3 cm. Thus the metal phase, in effect, is equivalent to a metal whisker or a thin metal film. These are strong because they have so few dislocation sources within them. T. D. Gulden and J. C. Shyne (authors' reply)—It is to be expected that the arrangement of dislocations in the indium-glass composites would be quite different than that observed in annealed pure metals. The dislocations probably exist primarily as segments connecting the dispersed particles. These segments and discontinuities at the very large area of particle-metal interface could act as dislocation sources. For this reason it was considered unlikely that the very high observed creep strengths were due to a low density of dislocation sources. A more likely explanation is that the distance a dislocation can glide is limited by the interparticle spacing. The particles averaged about twenty in diam and were less than 10 µ apart in the 40 pet composite. It seems reasonable to assume that a dislocation loop in a volume of metal surrounded by these relatively large particles would not bow out around them but would be restricted to the region between particles. A general expression for creep rate is given by the product of the dislocation source density, the average rate at which loops are generated from a source, and the average area swept out by a loop times the Burgers vector magnitude. Assuming that the area swept out is limited by the interparticle spacing and the rate of generation of loops is controlled by the rate of climb of loops over second-phase particles, as suggested by Ansel and Weert-men,9 a calculation of the dislocation source density may be made from the experimentally observed creep rates. The result comes out 10" to 10" per cm3 which seems reasonable in view of the assumptions involved. Thus it is concluded that the anomalously low creep rates that were observed were due not to a low dislocation source density but rather to a limitation on the area swept out by each dislocation loop.

Jan 1, 1964

By Robert W. Hunt

Delays in the completion of the alterations to the plant at the works of Messrs. Oliver Bros. and Phillips, in Pittsburgh, coupled with the increased demand for metal made from regular Bessemer pig, placing the firm many hundreds of tons behind in their deliveries, prevented Mr. Henry W. Oliver, Jr., from redeeming his promise to place his works at my disposal for further tests of high-phosphorus irons, until May 5th. Upon that date, I assumed charge of the operations in his steel-plant. Mr. Oliver had purchased Neshannock pig as a basis for a supply of phosphorus. My information is to the effect that this iron is made from low-grade Lake Superior ores and mill-cinder, the latter "ore" being utilized to about 40 per cent. of the total mixture. At all events the pig had quite as much phosphorus, and in as varying quantities, as the most exacting could desire. My experiments of last fall had well satisfied me as to the effect of from 0.35 to 0.55 per cent. of phosphorus in the Clapp Griffiths metal. Hence at this time my first trials were directed to

Jan 1, 1886

By J. A. Morgan

IN the art of roasting sulfides it is well known that the lower the temperature and the higher the pressure of SO, the larger will be the amount of sulfate present in the product. However, the mechanism of sulfate formation is not generally understood. The following experiment" demonstrates in a direct way that, in the roasting of Cu2S, the sulfate forms from the reaction of Cu2O, formed by the oxidation of Cu2s, with gaseous SO, (or SO3) and 0,. Thus, the sulfate does not form at the sulfide surface. The reaction at the sulfide surface is the same whether or not sulfate is formed. Using an indirect method, Ong, Fassell, and Wadsworth' infer that sulfate forms after oxidation, during the roasting of sphalerite, agreeing with the observations of this paper. The method presented here of demonstrating that sulfate forms after formation of Cu2O is to roast a sample of Cu2S and then to locate and identify the phases formed.' A solid cube of cuprous sulfide, made by melting Fisher reagent grade Cu2S powder and measuring about 1.5 cm on edge, was placed on a Nichrome wire grid suspended over the top of an Alundum combustion boat. The assembly was placed in a tube furnace at 600°C and oxygen gas, flowing at 0.60 liters per min, was passed around the specimen for 24 hr. The furnace tube diameter was 1.5 in. The partially roasted sample was removed from the furnace and impregnated with resin No. BR 0014, obtained from the Palmer Products Co., and the impregnated sample was then mounted in Lucite. A cross section was obtained by grinding and the surface was prepared by the following steps: 1) grinding—60 grit, 3M disk, dry; 2) preliminary polishing —60 through 600 grit, 3M disk, dry; 3) polishing— 8 µ diamond putty, silk cloth; and 4) final polishing —1evigated magnesia in isopropyl alcohol, Selvyt cloth. The color micrograph of the polished surface is shown in Fig. 1. The layers present in the micrograph are given along the side. The comwositions of the various layers were established by Debye-Scherrer patterns. From this evidence the following sequence of reactions which occur in the roasting of Cu2S is inferred: 1) The oxidation of Cu2S occurs with oxygen which has been transported through the oxide-sulfate layer by either gaseous or solid state diffu- sion. The products of this reaction at the Cu2S surface are Cu2O and SO,. 2) The SO, diffuses out through the pores in the Cu2O and finally reaches a position in the Cu2O where the oxygen pressure and the SO, pressure have values such that the thermodynamic conditions for the formation of CuSO4 are fulfilled. Then, the mixture of SO2, SO3, and oxygen reacts with the Cu2O to form CuSO1. 3) The CuSO, decomposes by the evolution of SO,, or SO, and O2, to form the basic sulfate. This is reasonable, since the SO, gradient will decrease toward the oxygen gas phase from the CuSO4 layer. 4) For this same reason the basic sulfate will decompose to form CuO. The above sequence of events is based on the assumption that diffusion through the oxide and sulfate layers, rather than the reaction at the sulfide-oxide interface, is rate-determining. This assumption is supported by the observation that these oxide and sulfate layers combined are almost nonperme-able to the flow of gases through them. Acknowledgments This research was supported by the U. S. Air Force, through the Office of Scientific Research of the Air Research and Development Command. The authors wish to acknowledge the helpful suggestions of Ralph Wells of the Applied Research and Developmeit Laboratory, U. S. Steel Corp. References E. A. Peretti: A New Method for Studying the Mechanism of Roasting Reactions. Discussions Faraday Soc. (1948) 4, p. 174. - J. N. Ong, Jr., M. E. Wadsworth, and W. M. Fassell. Jr.: Kinetic Study of the Oxidation of Sphalerite. Trans. AIME (1956) '206, pp. 257-263; Journal OF Metals (February 1956).

Jan 1, 1957

By H. Biloni

A metallographic study of solute segregation produced during controlled solidification of Sn-Pb alloys has previously been reported.' It was found that the growth conditions which produced well-developed cellular substructures led to severe segregation, and even at solute concentrations of 0.2 wt pct Pb regions of a lead-rich phase were formed at the junctions of cell boundaries (nodes). Similar sample preparation and etching techniques have now been applied to several tin alloys at more dilute concentrations. The crystals were solidified uni-directionally under less-severe growth conditions so that the predominant interface structure was composed of two-dimensional cells.* Binary alloys with lead, using 9.999 pct Sn as a solvent, and ternary alloys with lead and bismuth or lead and antimony, using zone-refined tin as a solvent, were examined. The liquid was decanted from the growing crystals in all cases to reveal the interface structure and ensure that two-dimensional cells were being formed. However, since interference may arise from a liquid layer that clings to the interface during decanting,3 an examination of the segregation pattern was always made behind the interface. In all cases, the structure within the bulk of a crystal at greater than 1 cm behind the decanted interface was substantially the same as that nearer the interface. Representative photomicrographs of the dilute Sn-Pb alloy are shown in Figs. 1, 2, and 3. Most observations are similar to those of the previous investigation. For example, the solute concentration at the cell walls is higher than in the intercellular regions; where cell boundaries meet, the segregation is enhanced; the macromosaic or stria-tion substructure and grain boundaries show enhanced segregation; there is also a depletion of solute at cell walls near a striation boundary, as Spittle et a1.4 have observed at decanted interfaces. Not all these observations can be seen in the photos shown since attention has been focused on a special feature; as evident in the photomicrographs, cer-

Jan 1, 1965

By W. A. Dickinson, H. F. Hendershot

THIS paper is a brief discussion of the past and present methods employed by the Huntington Works of The International Nickel Co., Inc., in the production of nickel and high nickel alloy seamless tubing. The various operations for both hot and cold processing will be considered in their natural sequence, together with the processing characteristics of the high nickel alloys and some descriptions of the equipment used. The tools and lubricants currently in use will be described. This discussion will relate primarily to nickel, Monel,† and Inconel,† since these are the most common of the many alloys processed into tubing at the Huntington Works. The nominal compositions of the materials are shown in Table I. CONVERSION FROM SOLID BILLETS TO TUBE SHELLS History The commercial production of seamless nickel and high nickel alloy tube shells is a comparatively recent development, the first nickel shells having been produced in 1922, Monel in 1930, and Inconel in 1931 on rotary-type piercing mills. Rolled or forged billets, ranging from 3 ½ - to 7 ½ in. diam, were pierced to produce shells ranging' in size from 4 3/8 in. OD X 0.180 in. wall to 8 3/8 in. OD X 1.0 in. wall. After piercing, the shells. were further processed by hot rolling, reeling, and sizing. Subsequent to these operations the shells were either supplied to the trade as "hot finished" tubes, or were processed by cold drawing to smaller sizes at the Huntington Works of the International Nickel Co. The extrusion of nickel and high nickel alloys also may be classed as a relative newcomer to the field of hot-forming methods, for it was not until 1928 that the commercial extrusion of these alloys was begun on a 600 long ton vertical extrusion press installed at Zenith Works of Henry Wiggin and Co., Ltd., Glasgow, Scotland. This press did considerable pioneer work and the results were so favorable that in 1937 a -2200 long ton horizontal press was installed. The quality of the inside surface of the tubing produced on this press was superior to that produced by piercing on a rotary-type mill and, as a result of this experience, a 4000 ton horizontal extrusion press was installed at the Huntington Works in 1943. Billet Preparation The first step in the extrusion, process is the selection of ingots with good hot malleability, as indicated by the test described by Martin and Bieber.1 Ingots then are forged into rough rounds which are machined to the desired billet diameter on a "bar peeler." This machine consists of a rotary head which carries the cutting tools and is driven by a 200 hp, dc motor. The feed mechanism consists of hydraulically driven input and output carriages on the respective sides of the cutter head. The diameter of the forgings used and the machined size or "billet diameter" that corresponds to the four different sizes of

Jan 1, 1951