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By A. U. Seybol

Eight binary iron alloys were examined after ion nitriding experiments to determine the behavior of the following elements: Al, Mo, Mn, Si, Ti, V,Cr, and C. Only Al, Cr, Ti, and V additions caused hardening in binary iron alloys. A few steels were examined to see the effect of Cr, Cr + Al, Cr + Ti, and Cr + V. It is suggested that a useful new class of ni-triding grade steels might be those containing about I pct V. The nitriding of steel, first described by Fry1 about 45 years ago, rapidly attained commercial application with very little knowledge of the fundamentals involved. While Fry,' in describing the status of nitriding in 1932, apparently correctly postulated hardening by precipitated nitrides, the details of the nitriding process were not understood, nor has the situation changed much since that time. It is also interesting to note that the compositions of some typical nitriding steels given by Fry at that time have changed little in the intervening years. Currently used nitriding steels owe their surface hardening to either chromium (as in 4340 steel) or aluminum plus chromium as in the Nitralloy grades, where both CrN and AlN appear to contribute to harden ing. Titanium additions have been studied experimentally, but thus far titanium steels have not won wide commercial acceptance. This subject will be expanded later. The orthodox ammonia nitriding process has been reviewed very adequately many times as in Jenkins3 and Case and VanHorn,4 and their is no need to outline the process here. Ion nitriding is not as well-known, although there have been several descriptions5-9 of the process given, sometimes with comparisons with the ammonia process. Most of these papers are primarily concerned with a description of the equipment, or of the physics or electrical engineering aspects of ion nitriding, but Noren and Kindbom9 gave the results of a metallurgical investigation using both processes. In brief, ion nitriding is carried out in a vacuum chamber from which the air is exhausted and replaced by a N2-H2 mixture, typically containing 10 to 20 pct N2, at about 5 to 10 torr pressure. While ammonia gas has also been used in ion nitriding, there is no evidence that ammonia makes any improvement in the ion nitriding process. A few hundred volts dc is applied between the grounded container wall (positive) and an insulated center post supporting the work (negative) to be nitrided. A glow discharge is created in the ionized gas, accelerating positive nitrogen ions to the work. These ions contain enough energy to form the normally unstable Fe4N "white layer", thus establish- ing surface nitrogen solubility characteristic of the a Fe/Fe4N equilibrium. This creates a substantial concentration gradient, driving dissolved nitrogen into the steel. The temperature employed is in the same range (around 500" to 550°C) as in ammonia nitriding, but because of factors which are not understood at present the nitriding time is ordinarily considerably reduced in ion nitriding. Other advantages have been cited,9 but it is not the purpose of the present work to contrast the two processes. The present objective was to examine the behavior of binary iron alloys during ion nitriding with respect to the microstructure, hardness level, and depth, and to examine some of these factors in steels as well. In this way it was hoped to be able to find out something about the individual role of these elements in steels. While all the work was done by ion nitriding, there seems to be no reason why any conclusions reached would not equally apply to ammonia nitriding, excepting only the kinetic aspects of the process. Another objective was an exploration of the critical-ity of the ion nitriding variables: gas composition, pressure, temperature, and time. EQUIPMENT AND MATERIALS The equipment used was substantially as described by Jones and Martin.8 The vacuum tank was about 12 in. in diam by about 18 in. high, and consisted of water-cooled stainless steel, with a single small window at the top for viewing inside. This sat on a heavy mild steel base equipped with the main pumping port, pressure control port, and vacuum gaging. A series of variable resistances was interposed between the glow discharge and a large-capacity -40 amp variable primary transformer feeding a 1000-v transformer, but 600 v were about the maximum ordinarily used. With the small l-in.-round, 4-in.-thick discs used for nitriding, the electrical load was usually about 500 v at 0.8 amp. The specimen temperature was controlled by a stainless-steel sheathed chromel-alumel couple, whose junction was in the steel stool upon which the flat discs were placed. These were ground through 400 Sic paper. Cycling of the temperature controller caused -0.2 amp variation in ion current, providing an ample control band. The binary iron alloys were made from vacuum-melted hydrogen-deoxidized electrolytic iron and alloys of 99.9 pct purity. Cast ll-lb-square tapered ingots were forged and hot-rolled to about 11/4-in.-diam rounds. Discs of 1/4 in. thickness by about 1 in. diam were machined from the rods for nitriding specimens. The following alloys were prepared: 1 pct each of Mn, Mo, Cr, Ti, Al, V, Si, and an Fe-0.8 pct C alloy. EXPERIMENTAL VARIABLES Of the variables total gas pressure, nitrogen partial pressure, temperature, and time, only nitrogen partial pressure was found to be critical to the operation. A critical nitrogen partial pressure was found corre-

Jan 1, 1970

By G. L. Oldright, T. B. Brighton, C. M. Dice

The base bullion from the lead blast furnace contains varying amounts of the impurities left in the smelter feed by the concentrator, regardless of the method of smelter operation. These impurities may be held in part in mechanical suspension rather than being present as true alloys. However, usually there is little free space in the crucible in which to separate these drosses before the bullion is taken from the lead well. When such a dross is melted in a laboratory crucible and allowed to cool, the products obtained are lead bullion, speiss, and matte in well separated layers. Typical analyses of layers are: Analyses. Per Cent Element Bullion Speiss Matte Pb.............................................. 92.0 41.2 38.3 Cu.............................................. 2.4 36.3 40.6 As............................................... 4.0 16.5 4.3 Sb............................................... 0.7 0.2 0.4 S................................................ 0.6 1.9 13.1 Fe............................................... 0.0 0.0 0.0 Totals......................................... 99.7 96.1 96.7 The absence of iron in these products drossed from the blast-furnace bullion proves that the impurities for the greater part are not simply finely divided blast-furnace speiss or matte that has been dissolved or dispersed in the lead, but are held in solution by the liquid metal and rise to its surface as infusible compounds when the temperature of the bath is lowered. In general, the drosses made locally are metal sulphides and arsenides and not oxidized compounds. The large content of metallic lead also does not seem to be retained because of oxidized compounds

Jan 1, 1937

By AIME AIME

ENGINEERS in the past have been largely associated with private enterprise and there has been a considerable tendency on the part of some members of our profession to depreciate government service for engineers. We engineers must change our mental attitude about employment in government service, particularly in view of the present most friendly attitude of the U. S. Civil Service Commission toward engineers for major posts in our Government. We must also take a much more active interest in public affairs. It must be realized that the national-defense program, which we are now organizing, will require for its effectiveness large numbers of engineers skilled in a wide range of technical and administrative services. In fact, the success of this undertaking will depend largely upon the extent to which our Government can command expert engineering talent to serve during the emergency. There is an acute shortage of technical and supervisory engineering personnel not only in the industries concerned with national defense but also in the Army, Navy, and other defense agencies of the Government. By an Act of Congress, approved on Oct. 9. 1940. $9,000.- 000 was turned over to the U. S. Office of Education, the regular defense agency of the Government which has co-operated with higher education for

Jan 1, 1941

By Cyril Smith

A COMPLETE discussion of the literature on the subject of the influence of copper on iron and steel will be published elsewhere.1 The present paper is concerned especially with the precipitation-hardening of copper steels, and brief mention will be made here only of the work of Kin-near,2,3 Nehl4 and Buchholtz and Koster,5 who alone have studied this phase of the subject. Kinnear found that normalized low-carbon steel castings containing about 1.0 per cent copper on drawing at temperatures in the neighbor-hood of 530° C. (1000° F.) increased in tensile strength and yield point, with little decrease in ductility. The maximum effect was obtained with about 0.9 to 1.0 per cent copper, and when the copper exceeded 3 per. cent no improvement occurred on reheating. Kinnear did not study the effect of time of reheating-an all important factor where precipitation is concerned. Nehl,6 who apparently was unaware of Kinnear's work, recognized the change as due to precipitation and studied the interdependence of time and temperature of reheating, the temperature of the initial solution heat treatment, and the speed of cooling necessary to retain the bulk of the copper in supersaturated solu-tion and to give an increase in hardness and tensile strength on reheating. Nehl found that if the final rolling or forging temperatures exceeded 700° C. (1300° F.) it was not necessary even to normalize the steel, but full precipitation occurred on merely reheating the forged or rolled shapes at 500° C. (930° F.).

Jan 1, 1933

By M. E. Straumanis, S. M. Riad

The lattice parameter of 99.999 pct pure Ag rtlas redetevnzined and found to be az5 = 4.08626 5 0.000041 with the vefnzctiotz correction included); the expatzsion coejjicient between 10° and 65°C was 18.73 X10-6°C-1. The lattice paratneter increased upon solution indium in silver in good agrement with other authors. The solid-solubility limit around room temperature was at 20.4 wt pct of in, which suggests that the high-temperature solubility (at about 689°C) determined by other authors is too low. The expansion coejficient of si1ver increases with the itzcrease of indium content between 10° and 65° C from, 18.73 (In = 0) to 20.9 x 10-6°C-1 (In = 20.4 pct), being only very slightly influenced by small amounts of indium. The expansion coefficents of all solid solutions increarsed strongly with temperature, reaching values > 27 x 10- 6 800°C. ACCORDING to the Ag-In diagram,' the solubility of indium in silver (the a phase) extends to about 18 pct by weight at room temperature. However, there has been only one investigation of the solubility limit by X-ray methods—that of Weibke and Eggers.2 Hume-Rothery, Lewin, and Reynolds measured only the lattice parameters of Ag-In solid solutions3 as did Owen and Roberts4 and Adler and Wagner.' The thermal expansivity of four solid solutions was determined by Owen and Roberts4 in a temperature range between 25" and 300°C. In view of the limited amount of work on Ag-In solid solutions, it seemed appropriate to redeter-mine the lattice parameters and the room-temperature solid-solubility limit, to find the exact expansion coefficients of the solid solutions at about room temperature (between 10° and 60°C) and the expansivity up to 800°C, and finally to derive the thermal-expansion coefficients for any alloy within the solid-solubility region. THE ALLOYS AND THE DETERMINATION OF LATTICE CONSTANTS The metals used were 99.9991 pet pure, supplied by the ASARCO company. Both silver and indium were weighed accurately on an analytical balance in

Jan 1, 1965

By Guido Bassi

IT is known'" that secondary recrystallization occurs in copper sheet with at least 90 pct reduction after annealing at high temperatures, 700" to 1000°C. Turkalo and Turnbull4 have found recently that secondary recrystallization might occur even after annealing at such low temperatures as 500°C for a high purity, coarse-grained copper sheet. It will be shown in the following that in an electrolytic tough pitch copper wire, with a high degree of deformation, secondary recrystallization might occur at even lower temperatures. A hot-rolled rod of 9.5 mm diam (temperature at which rolling commenced was 850°C) was drawn in continuous drawing machines to 0.4 mm, corresponding to a cross-section reduction of 99.8 pct. The texture in the center of the wire (the sample for X-ray analysis was etched to 0.15 mm diam) is a mixture of the [111] and the [loo] direction, as can be seen from Fig. 1. This is in accordance with the result of Schmid and Wassermann.' After a few minutes annealing of the wire at 200 °C, there is a noticeable recrystallization of the structure with a preferred orientation in the [l00] direction at the expense of the [Ill] deformation texture, as Figs. 2 and 3 show. Farnham and OINeill" reported a similar result. The final recrystallized structure shows mainly the [loo] orientation. There is however a small amount of [111] and random orientations. If the wire is annealed at 400°C, the recrystallized structure first shows a [loo] texture, Fig. 4, but as the annealing time is increased the fine-grained structure transforms into coarse grains, Fig. 5, giving a new preferred orientation, Fig. 6. The calculations show this to correspond to the [I121 direction. Even if the annealing that gives the primary recrystallization is carried out for six weeks at 20O°C, the same secondary recrystallization texture is obtained if the annealing is continued at 400°C. Schmid and Wassermann7 found the [I121 texture, but only after annealing at 1000°C or higher. The appearance of a secondary recrystallized

Jan 1, 1952

By J. D. Shaw, E. B. Gebert, D. O. Noel

It is, of course, expected that manufacture of the various metal powders should involve numerous methods adapted to the specific characteristics of the metals themselves. Several methods for powdering a particular metal may be available, but the physical characteristics of the powder as produced by the several methods may be quite different. In the final analysis, the application of the metal powder dictates the physical properties that the metal powder must possess, and this, to a very large extent, will determine which of several possible methods of manufacture is adopted. Sometimes powder of the same metal is produced by more than one method, each powder having specific characteristics that make it particularly suitable for its application. For purposes of classification, the various methods of powdering metals can be grouped as follows: 1. Machining. 2. Milling (by ball mills, stamps, attrition mills, etc.). 3. Shotting (pouring molten metal into water, air, etc.). 4. Granulation (by stirring molten metal while solidifying). 5. Atomizing (disintegrating by steam, compressed air, etc.). 6. Condensation of metal vapor. 7. Reduction of oxide powders. 8. Chemical precipitation. 9. Electrolytic deposition. 10. Sintering (for producing alloy powders). 11. Formation of an alloy followed by dissolving or otherwise removing one of the alloying constituents. Machining Turnings, cuttings, filings, etc., are, of course, produced as by-products in machine work of various kinds, and find certain applications as metal powders. For example, iron powder so produced is used extensively as a reducing or precipitating agent and as a constituent in certain hard-finish cements.

Jan 1, 1938

By D. O. Noel, E. B. Gebert, J. D. Shaw

It is, of course, expected that manufacture of the various metal powders should involve numerous methods adapted to the specific characteristics of the metals themselves. Several methods for powdering a particular metal may be available, but the physical characteristics of the powder as produced by the several methods may be quite different. In the final analysis, the application of the metal powder dictates the physical properties that the metal powder must possess, and this, to a very large extent, will determine which of several possible methods of manufacture is adopted. Sometimes powder of the same metal is produced by more than one method, each powder having specific characteristics that make it particularly suitable for its application. For purposes of classification, the various methods of powdering metals can be grouped as follows: 1. Machining. 2. Milling (by ball mills, stamps, attrition mills, etc.). 3. Shotting (pouring molten metal into water, air, etc.). 4. Granulation (by stirring molten metal while solidifying). 5. Atomizing (disintegrating by steam, compressed air, etc.). 6. Condensation of metal vapor. 7. Reduction of oxide powders. 8. Chemical precipitation. 9. Electrolytic deposition. 10. Sintering (for producing alloy powders). 11. Formation of an alloy followed by dissolving or otherwise removing one of the alloying constituents. Machining Turnings, cuttings, filings, etc., are, of course, produced as by-products in machine work of various kinds, and find certain applications as metal powders. For example, iron powder so produced is used extensively as a reducing or precipitating agent and as a constituent in certain hard-finish cements.

Jan 1, 1938

By T. C. King

AT the new Graham-Central Mill of Eagle-Picher, near Galena, Ill., material is simultaneously dewatered and introduced into the ball-mill scoop boxes by the use of variable-speed, 24-in. spiral classifiers. This arrangement has proved satisfactory in that the moisture content of the wet feed is reduced, thus allowing maintenance of density within the mills, and a constant feed at any desired rate to the mills is provided. In this mill the primary feed is wet crushed to minus 1/2 in. and preconcentrated by jigs to produce a bulk lead-zinc-iron concentrate and a waste tailing. The jig concentrate is then dewatered by a conventional dewatering classifier and stored in bins ahead of the ball mills. Even though this material is well dewatered, the discharge at the bin bottom is sloppy because of the gradual drainage of the water from the surface of the particles. Conventional belt feeders with vertical cutoff gates are unsatisfactory because of the flushing characteristic of the wet sand. The new installation employs 24 in. x 10 ft, 9-in. Simplex double-pitch spiral classifiers for feeders from the bin bottoms to the ball mill scoop boxes (fig. 1). These units are arranged with straight tanks and are driven by 5 hp motors through a U. S. Vari-Drive to provide a 4 to 1 speed ratio. Each bin discharges through a chute into the rising side of the spiral. The flushing characteristic of the material from the bottom of the bin is utilized to maintain a steady feed. A small amount of water tapped into the bottom of the bin insures uniform feed to the classifier. Excess clear water drains over the weirs. Feed rate to the mills is controlled by the variable-speed drives. The feed delivered by the spiral at a given speed setting is relatively dry, uniform, and steady, and as such is easily controlled by the operator. The classifiers are set on a pitch of 5 in. per ft and have a sand-raking capacity of from 8 to 32 tons per hr. It is believed that the solution of this problem offers possibilities for the storage of deslimed rod-mill sands and other similar products of the industry.

Jan 1, 1951

By John Henry Harden

IT appears that in the earlier days of anthracite coal mining, 1824-25, the Lehigh region mined 76 per cent. of all the coal sent to market. During the same period Wyoming sent 12 and 5 per cent. respectively, whilst the Schuylkill sent 11 and 18 per cent., the number of tons marketed being in those days very small indeed. In the year 1828 the Schuylkill region mined over one-half of all the coal sent to market, and continued to do so for thirty years (with the exception of the year 1831), until 1858 ; since that date the pro¬duction has declined very steadily in comparison with the other regions, until, in 1876, it was only 34 per cent. Wyoming, in the year 1820, was mining 40 per cent., but the production of all the regions was very small ; in six years it declined to 5 per cent., increased to 34 per cent. in 1831, declined to 10 per cent. in 1838. Since which time the increase has been gradual, until 1873-75 Wyoming produced over 50 per cent. of all the anthracite coal sent to market. In 1867 the production exceeded that of Schuylkill, and has continued to do so since that time. In the year 1876, during the existence of the " coal combination," Wyoming lost 9 per cent. ; during the same time Lehigh gained 7 and Schuylkill 2 per cent. over their relative production of the preceding year, the decrease of Wyoming being two and a half million tons, the increase of the Lehigh one million, the decrease of the Schuylkill nearly three-quarters of a million. The extraordinary production of the Lehigh region at a time of decreased demand and in opposition to an agreement with the other regions to limit the supply to the supposed demand was the cause of the disagreement which ultimately broke up the combination of the great coal-producing and carrying companies. The Lehigh region produced very steadily, from 1829 to 1854, an average of about 22 per cent. of the whole production. From 1854

Jan 1, 1877

By T. C. King

AT the new Graham-Central Mill of Eagle-Picher, near Galena, Ill., material is simultaneously dewatered and introduced into the ball-mill scoop boxes by the use of variable-speed, 24-in. spiral classifiers. This arrangement has proved satisfactory in that the moisture content of the wet feed is reduced, thus allowing maintenance of density within the mills, and a constant feed at any desired rate to the mills is provided. In this mill the primary feed is wet crushed to minus 1/2 in. and preconcentrated by jigs to produce a bulk lead-zinc-iron concentrate and a waste tailing. The jig concentrate is then dewatered by a conventional dewatering classifier and stored in bins ahead of the ball mills. Even though this material is well dewatered, the discharge at the bin bottom is sloppy because of the gradual drainage of the water from the surface of the particles. Conventional belt feeders with vertical cutoff gates are unsatisfactory because of the flushing characteristic of the wet sand. The new installation employs 24 in. x 10 ft, 9-in. Simplex double-pitch spiral classifiers for feeders from the bin bottoms to the ball mill scoop boxes (fig. 1). These units are arranged with straight tanks and are driven by 5 hp motors through a U. S. Vari-Drive to provide a 4 to 1 speed ratio. Each bin discharges through a chute into the rising side of the spiral. The flushing characteristic of the material from the bottom of the bin is utilized to maintain a steady feed. A small amount of water tapped into the bottom of the bin insures uniform feed to the classifier. Excess clear water drains over the weirs. Feed rate to the mills is controlled by the variable-speed drives. The feed delivered by the spiral at a given speed setting is relatively dry, uniform, and steady, and as such is easily controlled by the operator. The classifiers are set on a pitch of 5 in. per ft and have a sand-raking capacity of from 8 to 32 tons per hr. It is believed that the solution of this problem offers possibilities for the storage of deslimed rod-mill sands and other similar products of the industry.

Jan 1, 1951

The following is an incomplete list of members and guests who called at Institute headquarters `during the period Aug. 10, 1918 to Sept. 10, 1918. Amil A. Anderson, Hill City, S. D. A. A. Holland. H. G. S: Anderson, Hurley, N. Al. Paul S. King, Wilmington, Del. Louis A. Barton, Capt., Engineers, U. S. A. Herbert G. Officer, Washington, D. C. K. Baumgarten, lst Lieut., U. S. R. A. B. Parsons. Charles W. Boise, Belgian Congo. Robert R. Pollock, San Francisco, Cal. Henry C. Carlisle, The Pas, Manitoba. Frank A. Smith, Edgewood, Md. J. Ross Corbin, Boyertown, Pa. Edward C. Thompson, Kennett, Cal. S. Le Fevre, Forest Glen, N. V. Malcolm M. Thompson, Morsemere, N. J. Harold P. Ford, Cleveland, 0. Lester C. Uren, Berkeley, Cal. William L. Hogg, Waynesboro, Va. Harold W. Aldrich has been appointed assistant general superintendent of the Inspiration Consolidated Copper Co. at Inspiration, Ariz. Capt. Percy E. Barbour, formerly with the New York State Troopers, has been granted a leave of absence from the Department for the period of the war, by the Governor, and has been appointed Captain in the Engineer Corps, U. S. A. He served on the Mexican border in the New York State National Guard. A. C. Barke, formerly with the United States Smelting, Refining and Mining Exploration Co., has accepted a position with the United States Fuel Co. at' Salt Lake City, Utah.

Jan 10, 1918

By S. Floreen

Seven iron alloys ranging from 5 to 12 pct Ni and 5 to 14 pct Cr were studied. All alloys transformed to bcc massive martensites. Tempering increased the strengths , probably because of relief of residual stresses generated by the martensite transformation. The major strengthening mechanism appeared to be solid-solution hardening by nickel and chromium. Studies of the work-hardening behaviw, of the effects of prior austenite grain size, and of the effects of changing strain rate and test temperature gaue results very similar to iron or low-alloy steels. Increasing nickel contents markedly improved the toughness at subzero temperatures. Studies of the flow properties did not, however, indicate the reason for the beneficial effect of nickel on toughness. The marine atmosphere corrosion resistance of the alloys was improved primarily by chromium additions, but increasing nickel contents were also beneficial at low levels of chromium. J\ number of maraging and PH stainless steels are strengthened by precipitation hardening in a low-carbon Fe-Ni-Cr martensite matrix. To some extent the resultant properties of these steels must depend upon the properties of this matrix. The present study therefore was conducted to evaluate the transformation characteristics and mechanical properties of a series of Fe-Ni-Cr martensitic ternary alloys. A limited evaluation of the corrosion resistance of the alloys in marine atmosphere was also made. ALLOY PREPARATION Seven 100-lb air induction melts were prepared using electrolytic iron, nickel, and chromium metal additions. The initial Fe-Ni charge also contained 0.05 wt pct graphite to produce a carbon boil during melt down. After melting of the base charge, the heats were refined with 0.1 wt pct additions of manganese, silicon, aluminum and titanium and poured into cast-iron molds. The ingots were homogenized at 1250°C and uni-directionally hot-rolled to 2-in. plate. They were then homogenized another hour at 1250°C, and unidirection-ally hot-rolled to %-in. plate at a finishing temperature of approximately 1050°C. The compositions of the heats are given in Table I. Two additional heats were prepared as 40-lb vacuum-induction melts using electrolytic iron, nickel, and chromium metals, and commercially pure molybdenum chips. A carbon boil, and 0.1 wt pct additions of aluminum and titanium were again employed, but manganese and silicon were not added. The heats were converted to %-in. plate using the procedure described above. The compositions of these heats are included in Table I.

Jan 1, 1967

By R. J. Wasilewski

The resistivity of single crystal and of polycrystalline metal has been determined between 77° and 1500°K. At comparable purity, the resistivity of the poly crystalline metal differs from that calculated from the axial resistivity values. The observed anisotropy is briefly discussed. A zone refined titanium rod was obtained from F. J. Darnell.1 The hardness of this material varied between 52 and 64 Bhn, indicative of its high purity. Single-crystal specimens were cut out from a few large grains, elongated predominantly along <1120>. Resistance measurements were taken with specimens immersed in liquid nitrogen, solid CO,, and acetone, and at ice point, and then recorded continuously between room temperature and 1200" to 1250°C, throughout at least one full heating and cooling cycle at a rate of l° to 3°C per min. Four probe measurements were taken using spot-welded Pt wire 0.003 in. in diam as potential terminals, and the electromotive force drop was determined poten-tiometrically. A standard resistance, in series with the specimen, served to determine the dc current (generally about 80 ma) in the circuit. In order to eliminate spurious thermal electromotive forces, the circuit polarity was automatically reversed at 5-min intervals, and the mean of the two adjacent readings taken as the true electromotive force value. The discrepancy between the readings at reversed polarities was generally of the order of a few µ v, as all the spot-welded joints were contained within a volume of some 5 mm cube. The relative resistance (R T/R 273o) variation with temperature is tabulated below, and shown in Fig. 1, as measured during the first heating run. The discontinuous drop in resistance, corresponding to the a — ß transformation, started for both initial orientations at 1170°K; i.e., some 15°K above the accepted value of 882°C (1155°K). Judging by the temperature ranse of transformation—some 30°K for the single crystal and 20°K for the polycrystal-line specimen—this difference is believed caused by the solution of the oxygen present initially on the surface of the specimens. The general trend of the resistance vs temperature shown in Fi,;. 1 is in qualitative agreement with that previously reported for polycrystalline titanium metal. 2,3 Significant anisotropy is, however, indicated by the crossing over of the curves for <1120> and <0001> orientations at 273°, 650°, and 1000°K. This difference is most startlingly shown in Fig. 2, where instantaneous temperature coefficients (l/R273 x dR /dT) are plotted for both the first heat-

Jan 1, 1962

By L. T. Larson, M. L. Picklesimer

The relationship between the apparent angle of rotation of monochromatic plane polarized light and the tilt of the basal pole from the surface normal has been experimentally determined for zirconium over the wavelength range of 500 to 655 mp. This relationship allows the determination of the spatial orientation of the basal pole of an individual grain in a polycvystal-ling zivrconium specimen to within ±3 deg by three simple tneasurements with a polarized-light metallurgical microscope. The method of measurement is discussed in detail. THE optical anisotropy of materials having noncubic crystal structures has long been used to reveal features by polarized-light microscopy. Petrographers have used measurements of certain optical properties to identify and classify transparent or translucent minerals. More recent work (i.e., Cameron1) has extended such measurements to opaque minerals in reflected light. Few attempts have been made to make similar measurements on noncubic metals. Couling and pearsall2 have reported that a sensitive tint plate can be used in a polarized-light metallurgical microscope to determine the position of the basal-plane trace in a grain of polycrystalline magnesium. Reed-Hill3 has reported that the same technique can be used for zirconium. We have found that the precision of measurement can be increased to about ±0.5 deg by using a Nakamura plate4,5 to determine the exact extinction position after the sensitive tint plate has been used to locate approximately the basal-plane trace. This report describes a method for measurement of another optical property, the apparent angle of rotation. This measurement permits determination of the angle between the basal pole of a grain of a hcp metal and the normal to the surface of the specimen. When the two measurements are combined, the orientation of the basal pole in space can be determined from three simple measurements on a single surface. One to two hundred such determinations will permit plotting of a basal-pole figure for the polycrystalline material with reasonable accuracy. When normally incident, monochromatic, plane-polarized light is reflected from the surface of an optically anisotropic material, the light may be converted to elliptically polarized light, the plane of vibration may be rotated, or both may occur. The el- lipticity, the angle of rotation, and the reflectivity can be related to the indices of refraction and the absorption coefficients of the material.6,7 Ellipticity values can be determined with an elliptical compensator, but not with the ease and precision desirable for the present purposes. Measurement of the angle of rotation requires only the determination of the angle from the crossed position (90 deg to the polarizer) that the analyzer must be rotated to obtain extinction when the trace of the optical axis in the surface is at 45 deg to the vibration direction of the polarizer. The angle of rotation of the analyzer is approximately 6/5 that of the true angle of rotation of the light as reflected from the specimen because there is a small amount of additional rotation produced during the passage of the reflected light through the mirror of the microscope. Since we are presently interested only in determining the tilt of the basal pole, the angle of rotation of the analyzer (the apparent angle of rotation of the light, i.e., uncorrected) can be used. Precision of the measurement can be increased substantially by the use of a Nakamura plate4,5 in determining the extinction position. In an optically uniaxial material (hcp or tetragonal crystal structure) the angle of rotation depends only on the optical properties of the material and the orientation of the optical axis of the grain relative to the plane of incidence of the plane-polarized light.7,8 Thus, in a metal such as zirconium, the apparent angle of rotation at the 45-deg position in any given wavelength of light is a direct measure of the tilt of the basal pole from the normal to the surface. If the optical properties vary with wavelength, the apparent angle of rotation for any given tilt of the basal pole will vary. None of the required information exists in the literature for zirconium nor for any other non-cubic metal. MEASUREMENTS ON SINGLE-CRYSTAL ZIRCONIUM A single-crystal sphere of zirconium 9/16 in. in diam was spark-cut from a single-crystal rod grown from iodide bar by an electron-beam zone-melting process.9 The damaged surface was removed by chemical polishing in a 45/45/10 mixture (by vol) of water, concentrated HNO3, and HF (48 pct) and then electropolishing at 50 v in a bath1&apos; of methyl alcohol and perchloric acid (95/5 by vol) at -70-C. The single-crystal sphere was mounted in a five-axis goniometer stage having a removable eucentric X-ray diffraction goniometer head for the two inner orientation axes. The basal pole of the single-crysta sphere was aligned parallel to a third axis of the goniometer stage by using the sensitive tint method to determine the basal-plane trace at several rotational positions of the sphere. The alignment was then checked by removing the sphere and eucentric gonio-

Jan 1, 1967

By Ernest R. Dickie

BRIEFLY, the ore body of the Bagdad Copper Corp., Bagdad, Ariz., is a monzonite porphyry carrying copper values fairly evenly distributed from the surface down through the primary zone. Tabular in shape, the ore body extends over several hundred acres. The oxidized zone averages about 60 ft thick and assays about 0.50 per cent copper. Under this is the chalcocite zone, or the zone of secondary enrichment, which averages about 100 ft in thickness and assays about 1.4 per cent copper. Under this zone lies the primary zone which extends in places to a known depth of about 150 ft and averages in grade about 0.60 per cent copper. Several years ago the block-caving method of extracting the ore from the chalcocite zone was installed. Then it was necessary to draw only about 250 to 300 tons per day, the capacity of the old milling plant. Early in 1943 the new 2500-ton concentrator was put into production. Drawing ore from the developed stopes in sufficient tonnage to furnish the mill at capacity proved unsuccessful in more ways than one. First, drawing the ore at an accelerated rate caused a large amount of dilution, there-by lowering the grade, and also caused funneling through to the surface. The surface material was detrimental to milling metallurgy and development of these stopes was costly per ton of ore extracted. The grade of ore decreased. making it impossible to maintain a mill head of over 0.9 per cent copper. The

Jan 1, 1947

By J. S. Kasper, R. M. Waterstrat, B. F. Decker

THE existence of v phase in the Mn-Mo system was discovered in this laboratory several years ago,&apos; but neither the conditions of its formation nor its composition were known, and preliminary attempts to reproduce the phase were unsuccessful. We wish now to specify the information appropriate to phase formation on the basis of experiments performed since that time. The starting materials were in every case electrolytic manganese and high purity molybdenum. Two methods of preparation were employed: l—arc-melting varying combinations of the elements in an inert atmosphere and subsequent heat treating, and 2—sintering compressed mixtures of finely divided powders of the elements. In the latter method, the powders were first passed through 200 mesh screen and then compressed into cylinders of % in. diameter and % in. length, which were sintered at elevated temperatures in an atmosphere of dry hydrogen. For some samples, the sintering temperature was 1200°C (for 1 hr), and these were then heat- treated at lower temperatures for times up to 24 hr. Eventually it was found, for the proper composition, that essentially pure a phase could be produced by sintering at 1125°C for 3 hr. Quenching to room temperature was effected by means of a stream of cold, dry hydrogen in a water-cooled chamber. The arc-melting procedure was found to be unsatisfactory after an investigation of many samples at different compositions and temperatures. Large quantities of manganese were vaporized during melting and none of the products were homogeneous or contained extended regions of pure phase. Nonetheless, these experiments established that no formation occurs in the Mn-Mo system below 1115oC, and indicated, at least roughly, the composition range of interest for further exploration. The more definite results obtained from samples produced by the second method are given in Table I. A portion of sample 2 heated for 16 hr at 1000°C in a Vycor tube transformed to molybdenum plus unidentified phases of complex X-ray pattern. From these few results it appears that the region of phase is quite narrow in composition. It is of interest that the composition is such as to make for difficulties in correlating this structure on an electron atom basis with other a structures of iron, cobalt, and nickel. In that respect Mn-Mo shows the same anomaly as Mn-Cr and Mn-V systems.&apos; A second feature is that in common with the two other known molybdenum (Fe-Mo and Co-Mo), Mn-Mo v exists only at elevated temperatures. The X-ray powder pattern of the pure a phase of Mn-Mo is given in Table 11. It agrees well with the patterns established for other structures, especially with that for Fe-Mo as given by Goldschmidt.An attempt is being made to establish whether an ordering of the respective atoms occurs and such information will be reported in a future publication. Acknowledgment The authors acknowledge gratefully the assistance of Mrs. J. R. Belanger in some portions of this work. References &apos;J. S. Kasper, B. F. Decker, and J. R. Belanger: Journal of Applied Physics (1951) 22, p. 361. 2 A. H. Sully: Journal Inst. Metals (1951) 80, p. 173. H. J. Goldschmidt: Research (1949) 2, p. 343.

Jan 1, 1954

By E. A. Moulder

The mining industry is continually faced with problems involving dewatering, pollution, water supply, leaching and hydrochemical mining and prospecting. Greater application of the principles of ground-water hydrology to solution of these problems promises improved operating efficiency, increased safety and better public relations. Estimating the magnitude of dewatering for a proposed mine may be a major factor in determining the feasibility of proceeding with mine development. Diverting the source of ground water to an abandoned mine may save costly treatment of acid-mine drainage. Development of a large ground-water supply near an ore deposit may enhance the possibilities of a leaching operation. Detection of certain dissolved minerals in water from springs or wells may lead to hitherto unknown mineral deposits. Current efforts of industry, educational institutions and government are making these kind of events more commonplace. Dewatering of Mines The magnitude of dewatering problems was dramatized by a flooding that occurred last year in a gold mine in South Africa. During drilling operations at the West Driefortein mine, a major fracture was encountered from which large volumes of water issued necessitating evacuation of 1350 men from the mine. Dewatering required an increase in pumping of more than 80 million gpd. Models of ground-water systems are being used to test alternate plans for dewatering mines. Using the models in conjunction with computer optimization programs may lead to minimizing costs of operation. In addition to computer simulation of aquifers associated with phosphate deposits in North Carolina mentioned in last year&apos;s report, two USGS employees developed a model to estimate the amount of pumping required to dewater a mine site in Colorado.

Jan 1, 1970

By S. J. Im

Bupyung Silver Mines daily treats average 14 tons of concentrates containing 9,000 g Ag per ton. Bupyung Silver Refinery uses Merrill Crowe process to recover the silver from the leach solution containing 1.0 g/l Ag; Series of experiments were carried out to recover the silver from the solution by means of direct electrowinning in place of Merrill Crowe process. The recovery of the silver was 99% when the cell voltage and the retention time were 1.9 v and 3.0 hours, respectively. Power consumption was 3.2 Kwh/kg of Ag. It was found that impurity buildup was not significant during the recycling. The direct operating cost for the electrowinning was evaluated to be $ 0.35/kg of Ag.

Jan 1, 1984

By H. E. Cline

Mechanical properties of the eutectic between CoAl and cobalt were measured over a range of- temnperatures and strain rates for a variety of microstructures produced by directional solidification and by thermo-mechanical processing. Directional solidification led to rodlike, lamellar, and irregular microstructures. The unusually high volume fraction of the cobalt-rich rods and the lurge spacing of the rods were explained by the phase diagram. The hot-worked structure consisted of fibers of COAL in a cobalt-rich matrix. The roonl- tevlperature strength of the uvrought material increased with decreasing grain size but the 1000°C strength decreased with decreasing pain size. At high temperatures the directionally solidified tnaterial was stronger and less strain-rate-sensitice than the hot-rolled material. The fine-grained hot-worked ma-terial became superplastic at high temperatures, with tensile elongations greater than 850 pct, while at root temperature this material was ductile and impact-resistant because of the ductile matrix. Fracture occurred in the directionally solidified material at elevated temperatures by inter phase separation and at roorn temperature by cracks in the intermetallic phase. Growth of these cracks was impeded by the ductile cobalt-rich phase. It was found that the CoAl intermetallic remains ordered at elevated temperatures. DIRECTIONAL solidification of eutectic alloys has been used to produce structures consisting of parallel rods or lamellae. Although the spacing of the phases depends on the growth rate, it has been observed to be of the order of 1 µ in many eutectics. A strong intermetallic phase has been used to reinforce a ductile matrix in the rod eutectic A1-Al3Ni and the lamellar eutectic Al-Al2cu.1 The microstructure of the eutectics A1-A13Ni and A1-A12Cu remained aligned after samples of these alloys were exposed to temperatures just below their melting points for long times. Stability of the microstructure at elevated temperatures makes directionally solidified eutectics a candidate for high-temperature applications. Recently Thompson4 has developed the Ni-NiMo eutectic containing 40 pct NiMo lamellae, giving a tensile strength superior to nickel-base superalloys. Unfortunately, this eutectic oxidizes rapidly at elevated temperatures. By mechanically processing a two-phase structure, one may reach strengths as high as 700,000 psi, as demonstrated by drawn pearlite.5 In this case the strengthening mechanism was thought to be related to the fine substructure formed during deformation.5 However, a heavily worked structure may recrystallize and coarsen at elevated temperatures. Some worked eutectics such as Al-Al2Cu,6 Pb-Sn,7 and Sn-Bi7 have shown unusually large elongations in tension when tested at elevated temperatures. This phenomenon of large extension, called "superplasticity", was related to the fine grain size of wrought two-phase alloys at elevated temperatures. A mode of deformation of "superplastic" material has been shown to be grain boundary sliding,&apos; which has also been observed during creep of polycrystalline materials.9 The Co-A1 system was chosen for this investigation after examining the phase diagrams of binary eutectics." The high melting point of 1400°C, the aluminum content which was expected to give oxidation resistance, and the properties of the intermetallic CoAl were the chief factors influencing this choice. This eutectic consists of a mixture of the intermetallic CoAl and a cobalt-rich solid solution. The intermetallic CoAl has a large range of solubility and a CsCl structure." From the similarity between CoAl and NiAl one would expect CoAl to be ordered at elevated temperatures; however, specific heat measurements" show a transition at 800°C. West-brookL2 has measured the hot hardness of CoAl and found a rapid decrease in hardness above 600°C. The tensile properties and stress rupture properties of as-cast CoAl-Co eutectic were measured by Ashbrook and wallace13 who report a room-temperature tensile elongation of less than 1 pct. I) EXPERIMENTAL A) Sample Preparation. Experimental materials were prepared by directional solidification, by hot working, and by powder processing. The starting materials were electrolytic 99.9 pct pure cobalt and 99.99 pct pure aluminum. 1) Directional Solidification. A vertical Bridgman apparatus heated by induction was used to directionally solidify cylindrical ingots $ in. in diam and 5 in. long. The apparatus was first evacuated and then an argon atmosphere was introduced to retard evaporation. The ingots were contained in an alumina crucible inside a graphite susceptor that rested on a movable water-cooled base. The base was lowered out of the induction coil at a constant rate. Eight of the ingots were solidified using a drive rate of 2.5 cm per hr, two of the ingots at 1.2 cm per hr, and one ingot at 10 cm per hr. The eutectic composition Co 10 wt pct A1 was used in all but one ingot which had the composition of the stoichiometric CoAl intermetallic, Co 32 wt pct Al. 2) Mechanical Processing. At 1000°C the eutectic Co 10 wt pct A1 is a mixture of an intermetallic phase, Co 21 wt pct Al, and a cobalt-rich phase, Co 5 wt pct Al.10 These phases differ from the stoichiometric CO 32 wt pct A1 and pure cobalt because of the large solubility of this eutectic at elevated temperatures." Four rectangular slab ingots, 4 by 1 by 12 in. high, of Co 10 wt pct Al, Co 5 wt pct Al, Co 21 wt pct Al, and Co 32 wt pct A1 were cast for hot rolling. The cobalt was first vacuum-melted, H2-treated for 20 min,

Jan 1, 1968