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By George V. Smith, Daniel E. Sonon

Various mechanical properties of the Ni-Co-C alloy system were investigated to delineate the strengthening effect of carbon. Carbon concentration, cobalt concentration, vain size, temperature, and strain rate were varied so that thermal activation analysis and the Hall-Petch analysis could be used to evaluate the strengthening effect of carbon. Increasing carbon increased the strength of nickel and a Ni-60 pct Co alloy , with the effect becoming more pronounced at lower temperatures. Yield stress depended linearly on carbon concentration in nickel, but it depended on the square root of carbon concentration in the Ni-60 pct Co alloy. The Hall-Petch slope of nickel increased with carbon concentration; however, that of the Ni-60 pct Co alloy did not. The yielding behavior of these alloys was sensitive to composition, grain size, and temperature. Cobalt eliminated serrations in the flow curve of carbon-containing nickel at 300' and weakened them severely at higher temperatures. Pairs, or clusters, of carbon atoms appear to be responsible for the observed strengthening behavior. FLINN' conducted several experiments with carbon in nickel in an effort to provide information on the strengthening effect of interstitial impurities in solid solution in fcc metals and alloys. Strengthening which increased with decreasing temperature led him to conclude that carbon causes Cottrell locking in nickel. Fleischer2 analyzed Flinn's data and calculated that the strengthening effect of carbon in nickel was smaller by a factor of fifty than the strengthening effect of carbon in a! iron. Fleischer2 termed the magnitude of strengthening of carbon in nickel "gradual" and that of carbon in a! iron "rapid". He attributed "gradual" hardening to hydrostatic strains and localized changes in modulus of elasticity around solute atoms, whereas he attributed "rapid" hardening to tetragonal strains around solute atoms. Sukhovarov et a1.3-7 reported strain aging and serrated plastic flow in nickel, both of which they attributed to the presence of carbon. Serrated plastic flow has been rationalized by a process involving a series of dislocation pinning and multiplication steps.8, This process is more probable when screw dislocations are strongly pinned. Screw dislocations cannot be pinned by pure hydrostatic forces from the symmetrical strains of an interstitial impurity in an fcc lattice, except for small, second-order effects. However, they might be pinned by localized changes in modulus of elasticity around solute atoms,' by the pinning of the edge components of the partial dislocations of an extended screw dislo~ation,'~ or by clustered groups of solute atoms whose net elastic stress field is unsymmetric. The purpose of the present work was to investigate various mechanical properties of the Ni-Co-C a1loy system which are sensitive to pinning effects in order to delineate the specific pinning mechanism of carbon. Carbon concentration, grain size, temperature, and strain rate were varied so that thermal-activation analysis and the Hall-Petch analysis could be used to evaluate the pinning mechanism. Cobalt was added to lower stacking fault energy so that the number and extension of split, screw dislocations would be increased in order to test the possibility of pinning by carbon at extended screw dislocations. EXPERIMENTAL PROCEDURE Nickel and cobalt (both 99.98 pct-. pure) were melted with graphite in stabilized zirconia crucibles and cast at lo-' Torr to form Ni-C and Ni-60 pctCo-C alloys. Two ingots were heated to 1250°C and were forged to 1-in.-sq bars. These bars were machined to 4-in.-round bars, and then swaged cold to 0.144-in. -diam rods. Reductions in area of approximately 75pct were used with intermediate anneals at 900°C for 1 hr. The carbon content of batches of 0.144-in.-diam rods from each ingot was reduced to two levels by annealing 5-in. lengths in palladium-purified, dry hydrogen at 1100°C for 25 and 100 hr. The remaining material from each ingot was annealed at 10"5 Torr for 1 hr at 1100"~. These treatments gave a total of three carbon levels for both the nickel and the Ni-60 pct Co alloy. The 0.144-in.-diam rods were swaged to 70-mil wire, cut into test specimens, and then re crystallized at lom5 Torr in capsules for 1 hr at temperatures ranging from 760" to 1050" ~. The capsules were broken and the specimens were immediately quenched into water. Average grain size was measured using Hilliard's method of circular intercepts." Annealing twin boundary intercepts were counted in addition to grain boundary intercepts to establish an average grain size. Average grain sizes ranged from 5 to 140 p depending on the cobalt concentration and re-crystallization temperature. Tension tests were made in duplicate at various temperatures at a crosshead speed of 8.34 x 10"4 in. per sec with an Instron Universal Testing Machine. Specimens of 1-in. gage length with soldered ball ends were used at atmospheric and cryogenic temperatures. Pinch grips were used on specimens at elevated tem-

Jan 1, 1969

By S. Storchheim

MORE and more attention is being paid to the bonding of metals in their solid states. For a better understanding of this technique for joining metals and how it is affected by changes in temperature, pressure, and time at temperature and pressure, a detailed report concerning nickel to aluminum bonding has been published.' In order to broaden the knowledge accrued, some additional work concerning solid state joining of aluminum to copper and aluminum to zirconium was performed. The investigation of the Al-Cu system was considerably more extensive than the investigation of the Al-Zr system. For the A1-Cu system, not only were tensile sudies made but intermetallic penetration rate investigations also were carried out. The effect of temperature on intermetallic penetration rate for the A1-Cu system was determined at 11 tsi pressure, held 2 min. Procedure Apparatus: The hot pressing technique was the means of solid state reaction used and required the equipment depicted in Fig. 1. The following procedure was involved: The two metals to be reacted were placed in an aquadag-lubricated 18-4-1 tool steel die, 16 in. high by 1.440 in. ID, between punches of 1.366 in. diam made of the same material. A thermocouple well was located in the die body 3½ in. down from the top of the die, while another well was located centrally in the bottom punch 8½ in. from the bottom of the die. This die assembly was located in three cylindrical ceramic heating furnaces placed in tandem. Each furnace was controlled individually by a Variac power transformer. In turn, the die and furnaces were placed in a water-cooled stainless steel pot which could be evacuated. A cover, which contained a centrally located Wilson seal with an 18-4-1 1 in. diam ram running through it, was bolted on the pot. After sealing, the pot was evacuated by a roughing pump to 200 microns pressure, after which a diffusion pump was used to bring the pressure down to 5 to 15 u. At this pressure, the furnaces were turned on. As soon as they started to heat, out-gassing of the entire unit raised the pressure to 30 to 400 p. By the time the specimens were at temperature ready to be pressed, approximately 4/2 hr, the vacuum pumps had re-established the 5 to 15 u pressure. Once the desired temperature was reached, the required pressure was applied for a predetermined length of time to the 1 in. ram, through to the top punch, and to the specimen. When the time for keeping the specimen under pressure had elapsed, the pressure was released, the energizing coil current turned off, and the assembly allowed to cool. After cooling, the die was removed from the pot and the specimen was ejected. Specimen Preparation: Two different types of specimens were made for this investigation. One was for subsequent tensile testing, while the other was for determination of intermetallic alloy zone penetration into the parent metals. Tensile Bars—Commercially rolled copper pieces in. thick or zirconium sheet pieces 1/32 in. thick and 1.366 in. diam were placed between commercial 2-S aluminum rod 1 in. thick and 1.366 in. diam. This sandwich in turn was slipped into a 2-S aluminum sleeve 1.438 in. OD and 1.370 in. ID. This sleeve lined the couple up and prevented the aquadag lubricant from getting in between either the A1-Cu or Al-Zr interfaces. Immediately prior to the specimen assembly, the copper or zirconium was abraded on the flat surfaces with 320 grit silicon carbide paper, producing clean smooth surfaces. The aluminum was chemically cleaned just before assembly by: l—degrease in acetone, 2—distilled water rinse, 3—immersion for 3 min in 5 pct NaOH at 70" to 80°C, 4—distilled water rinse, 5—immersion for 2 min in 50 pct HNO3 solution at room temperature, 6—distilled water rinse, and 7—drying in a blast of gas. After the A1-Cu sandwiches were hot pressed and ejected, the specimens were machined such that the aluminum sleeve was removed, and the remaining aluminum was then threaded; the bar so produced was tested later for tensile strength. In all the instances where Al-Cu couples were tested, the specimens broke during the test at the Cu-A1 interface and never within the aluminum or copper. The ultimate tensile strength values at times showed considerable scatter for a set of given reaction conditions. Because of this, as many as three to five specimens were made for a particular set of conditions. The trend of the average tensile strengths obtained was not as conclusive as was the trend of the maximum tensile strengths, the latter values being obtained under optimum reaction conditions. Therefore, the values of ultimate tensile strength given herein are maximums.

Jan 1, 1956

By G. Horvay, J. G. Henzel

Nomograms and charts are provided which permit rapid determination of the mold-casting interFace temperature and the speed of solidification when a semiinfinite ingot is cast into a semiinfinite mold. The physical properties of the mold, the frozen metal, and the liquid metal are not assumed to be equal, but they are assumed to be temperature independent. The results are correlated with charts prepared by Paschkis and Hlinka—using Columbia University's Analog Computer—for the freezing of finite ingot slabs when a constant surface temperature is impressed, and with experimental cooling curves obtained by Pellini in sand and iron molds for 7 in.-sq steel castings. x = coordinate directed to right of zero (freezing direction) y = coordinate directed to left of zero (melting direction) e = position of freezing front (in x direction) ? = position of melting front (in y direction) $ = temperature (function of position and time) ? = fixed temperature 2L = width of finite slab Y = a fixed position in the semiinfinite mold, or the width of a finite mold (see Section 7) Properties y = density, lb per cu ft c = specific heat, Btu per lb deg F k = conductivity, Btu per ft hr deg F X = heat of fusion, Btu per lb k = k/Yc = temperature diffusivity, sq ft per hr* b - = = - heat diffusivity, Btu per sq ft deg F Vhr Subscripts 2 = pertaining to the still-liquid metal (case of freezing), or the medium which furnishes the heat (case of melting) 1 = pertaining to solidified metal (case of freezing), or to molten metal (case of melting)* 0 = pertaining to mold (case of freezing), or to the still-solid metal (case of melting) f = pertaining to fusion condition (eg.,?f - fusion temperature) i = pertaining to the location x = 0 (the mold-ingot "interface")

Jan 1, 1960

By Cyril Stanley Smith

BETA brass (consisting of approximately equal atomic proportions of copper and zinc) exists as a random solid solution at high temperatures, but at low temperatures [ ] an ordered structure is stable, with the copper and zinc atoms occupying alternate sites on the body-centered-cubic lattice. On cooling, ordering commences at a temperature of 450° to 470°C., depending on the composition. The degree of ordering progressively increases at lower temperatures until it becomes virtually complete at about 100°C. The electrical resistivity of the alloy illustrates the changes clearly (Fig. I). This type of reaction has been a favored subject for study by physicists. An [ ] excellent summary of the theory is to be found in a paper by F. C. Nix and W. Shockley.1 All published data on electrical conductivity, specific heat and other properties agree in indicating that the ordering reaction in beta brass takes place so rapidly that it cannot be prevented or even retarded by quenching. With most ordered alloys, cold-working induces disorder and

Jan 1, 1942

By F. C. Farnham

THERE has been very little, if any, uniformity in the reference datum used for magnetometer surveys. It has been the practice to choose a base station at which the magnetic field is assumed to be normal and call the difference in field strength between a given station and this base the anomaly at the given station. For small-scale surveys latitude and longitude corrections may or may not be applied, but for large-scale surveys such corrections usually are applied. The United States Coast and Geodetic Survey maps showing lines of equal magnetic intensity are commonly used to determine the normal latitude and longitude variation by scaling values from the map for given points and computing the change per mile north and the change per mile east. This method has been quite satisfactory for isolated surveys, but when two surveys originating at different base stations were extended until they joined, difficulty arose, not only because of discrepancies between base-station values, but also because of differences between the latitude and longitude correction factors used for the separate surveys. It is the purpose of this paper to describe a reference datum for magnetometer surveys which, it is believed, will eliminate most of the difficulty arising from this source. In order to be satisfactory, a general datum for magnetometer sur-veys should be as close as possible to the observed field and still he based on some assumed distribution of magnet poles, in order that the "normal" value of any component of the field for any given point may be computed to as many significant figures as desired. Such a field has been com-puted, and a comparison of the intensity of its vertical component with the average vertical intensity for the United States as shown by the U.S.C.G.S. map of lines of equal intensity for 1935 is shown in Fig. 1.

Jan 1, 1939

AT the meeting of the Board of Directors on Jan. 28, 1927, the tentative budget of this Institute for next year was discussed, and in connection with the evident necessity for a larger income to meet increasing demands for service, the advisability of in- creasing the dues of members, was brought up. W. Spen- cer Hutchinson advocated an upward revision of the dues "believing it necessary that the Institute have a larger income, in order that it may carry on necessary work and render adequate service to its membership." Since this is a matter that directly affects every member, .President Taylor was directed to appoint a committee, which he did, consisting of George D. Barron, W. H. Bassett, and R. H. Sweetser, with T. T. Read as secre- tary, to bring in a tentative outline of the main factors in the problem for discussion at the annual meeting, on Feb. 15, and to prepare, after they have had the benefit of the discussion at that meeting, a report for the board. The amount of the annual dues is fixed by the con- stitution and can only be changed by proposing an amendment to the constitution. This amendment would have to be submitted to the members by letter ballot at the time of the election of officers for 1928, so that no change can be made in the dues for 1927 in any case. WHY THE INSTITUTE NEEDS MONEY At the annual meeting past-president Reynders, as chairman of the executive committee made the follow-ing report, which since it admirably sets forth the rea-sons why an increase in the dues has been suggested, is included here. "The report of the president has covered the situation so fully that little is left for me to say. However, a word in regard to the functions of the executive com-mittee may not be out of place.

Jan 3, 1927

By J. B. Umpleby

PRoduction engineering in 1927 may be characterized by a great. clarification of fundamental conceptions, and many improvements in technique. During the year the profession has received tnarked recogni-tion by the industry and to an extent never before attained has become an integral part of it. History Petroleum production engineering is a new profession. Prior to 1925, when this Institute undertook the work, no forum existed for the open discussion of its technical problems. There was no attempt at a handbook of the subject prior to "Petroleum Production Methods by J. R. Suman, in 1921, and no textbook prior to Petroleum Production Engineering" by L. C. Uren, in 1924. As late as 1926, only six schools and universities offered special courses in petroleum production engineering. Prior to about 1923, engineers engaged by oil companies were used almost exclusively for construction and location work. Two of the leading production engineers in the Mid-Continent field, although with their respective companies more than twelve years, were not definitely assigned to production work until 1924. Both men now head large departments giving almost their entire time to production problems. Because of the newness of the profession, the leading production engineers of today have had their fundamental training in mining, civil, mechanical and electrical courses. Not unlikely this diversified training is in considerable part responsible for the amazing growth of the profession. I believe, however, that recognition is due principally to economic pressure within the industry which has directed attention more and more sharply on costs and efficiency. After all, the justification for the growth and continued development, of the profession is to recover more oil from a given unit of sand at less cost per barrel. In this new profession, it seems to me that greatest progress will result from focusing thought and effort on this single objective, and if I might offer one suggestion to the com-

Jan 1, 1928

By P. Stark, B. S. Lement

ACCORDING to Hanemann1 the hardness of retained austenite in a 1.7 pct C steel is increased by subsequent tempering. He reported that the hardness of this constituent increases only slightly on tempering to 300°F, rises more rapidly above this temperature, and attains the same value as the tempered martensite present in steel at approximately 480°F. The variation of hardness of both retained austenite and martensite with tempering temperature as obtained by Hanemann1 is shown in Fig. 1. Hanemann attributes the increase in hardness of the retained austenite essentially to continued formation of fine needles of martensite on tempering. Although he did not explain the actual mechanism involved, work hardening of retained austenite by the plastic deformation associated with such martensite formation appeared to be a possibility. Recently Lement, Averbach, and Cohen2 reported the existence of subgrains, about l000Å in diameter, in retained austenite and suggested that they may be delineated by a subboundary carbide. This raised the possibility that carbide precipitation might be responsible for the hardening reported by Hanemann. In view of these conflicting possibilities, an investigation" was carried out on a high purity, Fe-C alloy containing 1.7 pct C in order to clarify the nature of the phenomenon involved in the reported hardening of retained austenite. This investigation involved correlation of changes in microhardness and microstructure of the austenite as a result of tempering. Microhardness tests were made with a Tukon tester using a 25 gram load and a Vickers diamond. It was found that two groups of austenite hardness values were obtained after tempering at a series of temperatures up to 450°F, which was the highest temperature at which retained austenite regions could be identified microscopically. One group represents a high hardness level which in-

Jan 1, 1955

By R. B. Adair, J. S. Browning

The laboratory batch and continuous flotation pilot plant tests demonstrated the technical feasibility of recovering high grade mica concentrates from weathered mica pegmatite ores of Alabama and Georgia. The research indicated that combinations of anionic and cationic collectors may be used effectively for flotation of fine size mica from weathered pegmatite ores. In continuous tests, concentrates containing 98.5% mica were obtained from the Georgia pegmatite ore; the Alabama pegmatite ore concentrates contained 98.4% mica. The recoveries were 91 and 89% respectively. INTRODUCTION The principal uses of fine ground mica are as a filler in wallboard joint cement, as a filler and surface coating for roofing, as an ingredient in paints, and in oil well drilling mud. The mineral has other uses in the manufacture of rubber, wallpaper, plastics, welding rods, electric insulation, house insulation, and textiles, and as an annealing agent in metal treatment. In recent years, more than 99% of the domestic mica produced has been scrap and flake mica (mica which does not meet specifications for sheet mica and is used for producing fine ground mica). There has been a continued increase in mica production for several years, the 1963 production of scrap and flake mica totaling 117,251 tons.1 Ground mica is obtained primarily by crushing and milling pegmatites and schists. To a lesser extent, mica is produced as a byproduct of kaolin washing and feldspar and spodumene flotation operations. The processes used in recovering mica by crushing and milling pegmatites are generally simple, consisting of various combinations of alternate roll crushers and trommel screens that separate the mica and gangue at screen sizes coarser than 6-mesh. As these processes are designed to recover only coarse mica, high losses in the plant rejects are common. Large tonnages of tailings from the crushing and screening plants have been accumulated in a number of areas. Methods for treating such products were developed by the Bureau of Mines in 1941,2 but have not been generally applied. More recently, mica flotation research has been completed and published by the Bureau of Mines.3 These methods required complete removal of 150- to 200-mesh materials from the flotation feed with consequent fine mica losses. Later, the Bureau of. Mines investigated methods for-recovering fine size mica from pegmatite ores after desliming sufficiently to remove clay materials, but not so drastically as to remove the fine sands. This report summarizes the results of these studies. The process developed was effective on pegmatite ores from two locations and should be applicable to the commercial treatment of other mica-bearing pegmatite ores and fine rejects that have been accumulated at various mica-milling operations. DESCRIPTION OF ORES The ores used in the investigation were obtained from the Dixie Mines, Inc., Heflin, Alabama, and the Ruberoid Corporation, Hartwell, Georgia. The sample from Alabama contained muscovite and quartz, with a high percentage of clay, and minor amounts of biotite, kaolin, limonite and tourmaline. The mica in the ore was essentially all minus 4-mesh in size and was free of attached mineral grains. The Georgia sample contained muscovite and quartz, with minor amounts of biotite, kaolin, and limonite. The mica in the ore, which was essentially all minus 4-mesh, was liberated. Petrographic analyses of the two samples are given in Table I. THE ANIONIC-CATIONIC MICA FLOTATION METHOD Previous investigators2,3 have reported that complete desliming of mica ores at 150- to 200-mesh was required prior to flotation with cationic collectors to obtain satisfactory selective separation of the mica from the other mineral components. Numerous tests were made at the Tuscaloosa Metallurgy Research Center to determine if some reagent combination could be used to selectively float finer size mica without complete desliming. The investigation led to development of a process using a simple reagent com-

Jan 1, 1967

By AIME AIME

THE autumn is the time that nearly all the special groups within the broad field of the Institute's activitives chose for their own special meetings. The big annual meeting in New York in February has its own special advantages, but to realize them involves sacrificing others. A meeting of a smaller group with the subjects brought up for discussion much more closely limited to a single field of interest has some advantages that a big general meeting cannot possibly have. And so the custom has gradually developed of having these smaller meetings in the autumn, at con¬venient places, so the men will not have to travel too far from the job to be present. Sometimes the meetings have for their field of interest a single phase of mineral technology, and are called divisional, and at other times they cover a diversity of topics that are locally important in that geographical area, and are then called regional meetings. Of the five meetings to be held this fall, four are divisional and one regional. Two of the divisional meetings are to be held in the same place at the same time, but with programs so arranged that they do not conflict.

Jan 1, 1930

By D. F. Stein

In spite of the apparent usefulness of autoradiography in demonstrating segregation, it has had very limited success in demonstrating grain boundary segregation. Because of this limited success, a model system amenable to mathematical analysis was devised to determine which variables in the experiment are most important. As a result of these calculations, it was concluded that autoradiograPhy is a rather insensitive technique to measure grain boundary segregation. The range (energies) of the emitted particles (ß and a) must be low, and the concentration of the radioactive speczes at the grain boundary must be (in general) two or three orders of magnitude greater than the concentration within the grain. Because of these very restricted conditions , the limited success of the technzque is not surprising. In spite of the apparent usefulness of autoradiography in demonstrating segregation, it has had very limited success in demonstrating grain boundary segregation. Sulfur segregation in iron1 and possibly polonium segregation in Pb-5 pct B1 2 alloys are the only autoradi-ography experiments that have demonstrated segregation to grain boundaries in metals without the formation of a second phase. Segregation to a boundary without the formation of a second phase is often called Gibbs' absorption and is discussed by McLean in Chapter 5 of Ref. 10. There are several394 experiments showing grain boundary diffusion of a radioisotope, but this type experiment is not representative of equilibrium between the concentration of an element at a grain boundary and that in bulk, so it will not be discussed in this paper. In an attempt to determine if temper embrittle ment of low-alloy steels was associated with segregation of antimony to grain boundaries, a program to use auto-radiography (using Sb-125) was initiated. Even though other measurements strongly suggest that segregation is occurring during embrittlement, no evidence of grain boundary segregation was observed in the auto-radiography experiments. An attempt was also made to detect segregation of carbon (using C-14) to grain boundaries in iron during slow cooling. There is again strong indirect evidence7 that segregation occurs during such a treatment, but the autoradiography experiment gave no evidence of such segregation. Because of the failure of these experiments and the general lack of success by our metallographic unit in measuring grain boundary segregation using autoradi-ography, a model system amenable to mathematical analysis was devised to determine which variables in the experiment are most important. MODEL SYSTEM The model system is illustrated in Figs. 1 and 2. It is a semi-infinite bicrystal with a single grain boundary perpendicular to the top face. The width of the grain boundary, W, is defined as the region to which segregation has occurred and it is assumed that this region is of constant composition. The assumption of an infinite dimension is for mathematical reasons but the results of such an analysis (as will be demonstrated later) are valid for even very small specimens. It also is assumed that the measurement is not limited by means of detecting the radiation (photographic emulsions, counters, and so forth) but that the means of detecting radiation is linearly sensitive to the radiation and has infinite resolving power. The distance y is the perpendicular distance from the center of the grain boundary to the point at which the background radiation is measured and x is the integration variable. CALCULATION FOR BETA PARTICLES Two values of the intensity of radiation will be calculated, the intensity at the center of the grain boundary and the intensity far from the grain boundary. The radiation at the center of the grain boundary can be calculated in the following way. Assume a grain boundary of width W having a uniform concentration equal to Cgb + Cb where CGb is the excess concentration of the element under consideration at the grain boundary and Cb is the bulk concentration. The intensity of radiation, IgB, at the center of the grain boundary, is a consequence of the amount of radioactive material, decay rate, absorption, and geometrical factors which can be represented mathematically by the following expression:

Jan 1, 1968

By H. N. Thomson

(Butte Meeting, August, 1913.) GENERAL. THE Tooele plant. off the International Smelting & Refining Co. is situated at the mouth of Pine canyon, Tooele county, Utah. It is connected with the main line of the San Pedro, Los Angeles & Salt Lake railroad by the Tooele Valley. railway, and is about 7 miles from Tooele Junction. Fig,. 1 is a general view of the plant. The copper plant has been in operation since July, 1910, and the first blast furnace it the lead plant was blown in on Feb. 29, 1912. The location of the plant was selected on sloping ground with the idea of using gravity to the fullest extent and thus keeping labor at a minimum. Practically the entire plant is constructed of steel, reinforced concrete, and. brick.

Jan 7, 1913

By E. J. Krokroskia

Fletcher Mill is located in the southern part of the New Lead Belt in Southeastern Missouri, in the northwestern part of Reynolds County. Shaft sinking began in July, 1964. The mill went on stream in February, 1967, and reached the designed rate of 5,000 tons per day in July, 1968. The ore occurs approximately 1,000 feet below the surface as disseminated deposits of galena, sphalerite and chalcopyrite. There is no oxidation within the ore body and dissemination is not fine enough to present liberation problems with a normal grind. Mining is by the room and pillar method with rubber-tired diesel- propelled drilling and loading equipment. The ore is dumped through a 27-inch square grizzly into a 5,000-ton pocket. The underground primary crusher is automatically fed by a vibrating feeder and discharges directly into skip measuring bins. Hoisting is automatic, in balance, with 8. 5-ton skips dumping into a 1,000-ton mill bin. MILL The concentrator is a 5, 000 tons-per-day single section plant equipped to produce lead, zinc and copper concentrates. Contained under 35, 347 square feet of roof, without fine ore storage or remote crushing, and with sufficient automation to be operated by one man, the plant is compact, unique, and efficient in operation. The design

Jan 1, 1970

By M. M. Rao, P. G. Winchell

The growth rates of bainitic plates were measured at 400°C in Fe-Ni-C alloys containing 0.10 atom-fract~on nickel and 0.0012 to 0.0075 atonz-fraction carbon. The growth rates are adequately represented by where xc is nearly the atom fraction carbon of the bulk austenite and PXCy is nearly the carbon atom fractlon in the ferrlte of radiids p In equilibrium with austetzite. The form of the equation is that predicted by a model in which carbon diffusion in austernite controls the gvowth, but the numerical constatnt is two orders of magnitude below that suggested by the model. THE growth of bainitic plates in steel is often assumed to be controlled by the diffusion of carbon away from the advancing plate tip. This hypothesis predicts that the growth rate will increase as the carbon content of the austenite, xCz, is reduced toward the carbon content of the saturated ferrite comprising the plate tip, PxCY The growth rate should vary approximately as (xCg- pxCy)-1. Experimental observation of the growth behavior at low carbon levels should provide a significant test of this model. An alloying element in addition to carbon is required so that low-carbon austenite can be experimentally observed while undergoing bainitic transformation. Nickel was selected. The presence of nickel complicates the interpretation of the data in two ways: First, diffusion of nickel during the transformation would make analysis very difficult. Nickel is assumed immobile during the transformation. Second, nickel affects the solubility of carbon in ferrite and austenite in equilibrium. This effect has been evaluated.' At the completion of our experimental work Goode-now et al.2 published data in essential agreement with the observations to be reported here. Since their discussion is abbreviated and their data are scanty in the region of interest, we believe the present work is of significance. I) THE MODEL OF BAINITIC PLATE GROWTH The rate of lengthening of a plate is assumed to be controlled by the diffusion of carbon from the advancing ferrite-austenite interface into the surrounding austenite. The precipitation of carbides is assumed to be a secondary process. For ease of analysis the carbon-atom ratio,* pxCy, of austenite in equilibrium with ferrite which is convex with minimum curvature radius p, and the carbon-atom ratio, PxCY, of that ferrite in equilibrium with austenite are assumed independent of location on the ferrite-austenite interface. Since these carbon contents vary with the radius of curvature of the ferrite, p, their assumed positional independence must be held as an approximation. The consequences of these assumptions have been developed approximately by zener3 and Hillert,4 and the resulting equation for a platelet has been applied to bainite by Speich and cohen5 and Kaufman, Radcliffe, and Cohen.8 The Zener-Hillert equation* for plates is: The analysis of Hillert is supported by that of Hor-vay and cahn7 which involves no mathematical approximations but does include the assumption that the a/y interface coincides with an isoconcentration line. The solutions of Horvay and Cahn for elliptic paraboloids are replotted in Fig. 1. The shape of the paraboloid is expressed in terms of the ratio of the principal radii of curvature at its tip, A =p1/p2, which is also the ratio of the minor to the major axis of the elliptic cross section. The Zener-Hillert equation for plates is also plotted. The agreement is within a factor of two for (pxyaCr - xyC )/(xyC - PxCaY) between 0.5 and 100. This is the range of interest here and in most other work on bainite. The original form of the Zener-Hillert equation was the form given above with the right-hand side replaced by (pxCya -xCy)/(PxCya). This replacement is not appropriate here. 11) THE EXPERIMENTAL PROCEDURE Alloys were prepared and three kinds of experiments carried out. Continuous-cooling-transformation experiments were carried out on wires by measuring temperature and resistance during continuous cooling. Isothermal-transformation experiments were carried out on wires by measuring electrical resistance as a

Jan 1, 1968

By Craig R. Smith, Warren Pfefferle

Tests were conducted utilizing large flat jack devices placed in a vertical slot for high pressure loading of rock to measure in-situ properties of a rock mass. The high pressure flat jack devices were used as a site investigation tool to obtain rock mass properties. Tests were conducted before and after a 100 ton surface high explosive detonation test to assess explosive effects on the rock. It was conclusively demonstrated by these tests that meaningful flat jack tests could be successfully accomplished; also, a significantly different response of the rock medium was measured as larger areas of rock were loaded. Surface jointing was severely disturbed by the explosion.

Jan 1, 1971

By Jerome S. Nelson, William S. Johnson

Seismic investigations at pre-construction sites commonly are limited to obtaining velocities and thicknesses of subsurface intervals which are useful in estimating construction costs, but are sometimes difficult to apply to project designing. This paper shows through a case history of the San Bernardino Tunnel Intake Tower, a part of the California State Water Project, that dynamic rock properties and dynamic resonant frequencies can be determined and velocity models constructed from in situ field studies and that these are theoretically correct after simplifying assumptions are made. These data can be used to confirm and extend information obtained by conventional methods such as drilling and laboratory static testing.

Jan 1, 1971

By AIME AIME

TRAINED as a mining engineer and with no little experience in the field of mining, his interests and activities later transferred to the alloying, fabrication, and physical metallurgy of nonferrous metals, principally silver, Robert H. Leach represents in his professional life both of the major phases of the fraternity of mining and metallurgical engineers. In his personal characteristics, his wide circle of true friendships, his kindly, sympathetic interest in the problems of his fellow engineers, be they the junior men of the mineral industries or the mature and experienced men, he typifies the characteristics and attitude so desirable in the professional man.

Jan 1, 1939

In reply to inquiries and comments which have reached me since the publication of this paper, and in explanation of some seeming discrepancies between my statements in the text concerning the amount of displacement of the faults, on one hand, and certain figures in the plates on the other hand, I give here, with some additional remarks, my measurements of the displacements in the different sections, which it originally seemed unnecessary to print : By displacement, I mean neither the throw, i.e., the vertical distance apart of the two edges of a faulted bed (what Mr.

Jan 1, 1896

Organisation Place Date 1918 American Society of Mechanical Engineers New York, N. Y. Dec. 3-6 Society for Promotion of Engineering Education, with British Educational Mission Cambridge, Mass. Dec. 6-7 Geological Society of America Boston, Mass. Dec. 28-31 American Association for the Advancement of Science Boston, Mass. Dec. 27- Jan. 2.

Jan 12, 1918

By W. F. Boericke

THE recent completion by the United States Aluminum Company of a $4,000,000 addition to its plant at Massena, N. Y., consisting of a large blooming mill and structural mill, gives this organization, a subsidiary of the Aluminum Company of America, the distinction of possessing the largest aluminum rolling mill in the world, as well as the first mil1 in this country to roll aluminum exclusively. The plant is located near the international boundary line between Canada and the United States, about 3 miles from the St. Lawrence River, to take advantage of the development of cheap hydroelectric power which is needed not only for the manufacture of structural shapes from the ingots, but in the reduction of alumina to the metal by the well-known Hall process as well. A power canal from the St. Lawrence River to the power house on the Grasse River at the plant provides for the waterflow, which, coupled with a drop of 47 ft. in 2% miles, generates 80,000 hp. through vertical turbines. An additional 60,000 hp. is purchased.

Jan 1, 1930