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By F. P. Morawski, J. E. Schelske, J. R. Geddes, B. R. Eberts, D. M. Wilson, J. D. Jeffries

"The Griffith Mine is located 200 miles northeast of Winnipeg and is 30 miles south of Red Lake, Ontario. Owned by The Steel Company of Canada Limited and managed by Pickands Mather & Co., it has an annual rated capacity of 1.5 million tons of high-grade iron ore pellets with an analysis of 66.3 per cent iron and 4.5 per cent silica.Development of the mine and construction of the plant got underway in January of 1966 and operations began in February of 1968. The orebodies outcrop on the shore of Bruce lake and run under the lake. The ore in its crude form is a metasedimentary low-grade magnetite and occurs in a highly folded banded formation. The average iron analysis of the crude is 29 per cent and the over-all weight recovery is 32 per cent.In order to mine the portion of the orebody under the lake, the soft varved clay on the lake bottom was hydraulically dredged and a dyke constructed of rock, with till used to provide an impervious seal on the lake side of the dyke, prior to dewatering.Mining is carried out by conventional open-pit tech-niques. Ore dressing is achieved by combining one crushing stage and a two-stage grinding system, with beneficiation by magnetic separation, hydroseparation and flotation. Agglomerating is done with conventional balling drums and pelletizing is carried out in shaft furnaces.Of interest and discussed in detail are the 32-foot autogenous cascade mills ."

Jan 1, 1970

By A. W. D. Hills, M. R. Moore

An apparatus has been developed in which metals can bc solidified under closely controlled unidirectional heat flow conditions. The metals are cooled by a multiple-air jet system, designed so that the heat transfer coefficient is uniformly distributed over the cooled surface. They are contained in a special furnace system of low thermal mass which enables unidirectional heat flow conditions to be rigorously maintained for certain specific cooling rates. This apparatus has been used to study the solidijication of pure lead and pure tin at zero superheat, solid metal thicknesses being determined by thermal analysis, and by dipstick readings. Detailed thermal balances have been drawn up on the experiments in order to determzne the cooling conditions that most rigorously correspond to unidirectional heat flow. Solid metal thicknesses, measured experimentally for these conditions, have beetz shown to agree closely with the theoretical wedictzons of different integml-profile methods. lt is concluded that any errors inherent in the integval-profile method are no greater than the errors inherent in experimental investigations of solidification. A knowledge of the influence of heat transfer rates on the solidification of metals is essential to the understanding and control of industrial casting processes. Since very few formal methods are available for solving the heat conduction equation under solidification conditions several authors have developed approximate techniques for doing so. One of the most promising is the integral-profile technique that has been used by Goodman,1 Hills,2,3 Tien4 and Hills and ~oore' to predict solidification rates under certain specific heat transfer coniditions. In the first of this present series of papers6 Hills has further generalized the method and developed a universal integral-profile technique that can be used to predict solidification rates under a wide variety of unidirectional heat flow conditions. Since the method is approximate it is necessary to investigate the accuracy with which it predicts actual solidification rates. A review of the literature7 shows that solidification rates have seldom been measured under accurately known heat transfer conditions and it was therefore decided to develop experimental techniques that would enable this to be done. Results obtained would then be available as a check on the approximate solutions already developed, and in the development of further solutions that would be applicable under more complicated conditions. The initial work in this experimental program which is described here, is concerned with the solidification of pure metals at zero superheat under unidirectional heat flow conditions. Subsequent experiments have been concerned with the solidification of pure metals at appreciable superheats, under varying unidirectional heat flow conditions and under two dimensional heat flow conditions. In a series of experiments recently initiated, the solidification of binary alloys is also being investigated. The results of these subsequent experiments, together with relevant theory, will be described in later papers. The solidifying metal has been cooled in all the experiments, by a multiple air jet system designed so that the heat transfer coefficient to the cooled surface is constant and is uniformly distributed over the surface. This type of system has been chosen since only one parameter is needed to specify the heat transfer conditions and since these conditions are analogous to those met in certain continuous casting processes.' Air cooling was chosen in preference to water cooling, however, since it offers a wider range of heat transfer conditions, and since it can be investigated by analogous mass transfer techniques. The first part of this paper discusses the existing integral-profile solutions that correspond to the heat transfer conditions used in the experiments, and describes the development and use of the experimental apparatus. In subsequent sections the heat transfer and solidification results are presented, and the various theoretical predictions are compared with them, and with one another.

Jan 1, 1970

By John R. Low

A number of cases of low-temperature, intergranu2ar brittle fracture of metals containing small amounts of certain impurities, have now been identified. Some degree of understanding of this phenomenon exists for the simpler binary systems of a metal and a single impurity, but the profound effects of other impurities and alloying elements in modifying this type of behavior remain unexplained. Current research in this area is reviewed and some of the newer techniques of investigation which should make possible a more quantitative study of the structure and composition of grain boundaries in impure metals are described. To indicate the subject matter of this lecture, we may begin by reviewing the experimental observations concerning low-temperature intergranular brittleness in impure metals, particularly those examples in which the embrittlement appears to result from what has been called "equilibrium grain boundary segregation."' These are the systems in which it has been impossible, at least up to now, to detect the presence of any second phase film at the brittle interfaces. When second phase films are present they are usually readily detectable by fractographic methods, often appearing as epitaxial films in geometric or dendritic patterns. An example is shown in Fig. 1 for the case grain boundary carbides in a sensitized stainless steel which failed by intergranular brittle fracture at 78?k2 In contrast to this type of embrittlement there are numerous examples of low-temperature intergranular embrittlement in which the fractographs are essentially featureless, for example, that of an oxygen-embrittled iron shown in Fig. 2. The only second phase particles visible are the small, widely separated, round oxide particles typical of the bulk material. The fracture surface is extremely smooth and the fracture path appears to follow the intergranular interface without deviation. This type of fractograph also implies that crack propagation has occurred without plastic deformation at the crack tip, since localized slip or twinning ahead of the crack would be expected to distort the interface and be readily visible in the fractograph. Such indications are occasionally seen in these fractographs, but are not characteristic. A second example of this type of fractograph is shown in Fig. 3, which is from a temper-embrittled, carbon-free, Fe-Cr-Ni alloy containing Sb, broken at 1OO?C.3 The similarity to the oxygen embrittled iron case will be apparent. In the case of the temper embrittled Cr-Ni ferrite containing antimony, it is possible to remove the embrittlement by suitable thermal treatment. The grain boundaries may then be examined by thin film transmission in the electron microscope for the material in both the nonembrittled condition and in the embrittled condition. Two boundaries are shown in dark-field transmission in Fig. 4, one in the nonembrittled

Jan 1, 1970

By W. N. McAnulty

Because so many interrelated technical, economic, legal and political factors are involved in evaluation of commercial mineral deposits, it is common practice today to assign such work to a team of specialists including geologists, mining engineers, metallurgists, lawyers, and economic evaluation experts. Each member of the team plays an important role; the role of the geologist is particularly important. The geologist involved with evaluation of fluorspar deposits needs all the geologic and economic training and experience required for evaluation of metallic mineral deposits. Few, if any, industrial or metallic minerals occur in so many geologic environments as fluorite. Fluorspar, and aggregate of rock and mineral matter containing enough fluorite to make a commercial deposit (ore), is somewhat more limited in its modes of occurrence than fluorite, but it too is found in a variety of environments.

Jan 1, 1970

The proposed classification scheme is based on two primary parameters, one for petrographic composition and the other for rank, both being determined with microscopic techniques. The scheme has been applied to a wide range of Australian coals and found to provide a useful means of relating their inherent properties to properties such as volatile-matter yield, crucible swelling number, and calorific value, which will determine how these coals might be used commercially.

Jan 1, 1970

By Klaus W. John

The geologic factor of greatest significance in rock mechanics and rock engineering is considered to be the geologic structure represented by joints, faults, and other planes of weakness. This geologic structure differentiates between the rock element and the rock system composed of these elements. Only during the last decade has the difference of the technological properties of element and system been recognized but this appears to be more in theory than in engineering practice. If rock mechanics is to achieve real significance in engineering practice, it has to provide methods of analysis which are realistic compromises between the best representation of the actual conditions and pragmatic engineering. The rock mechanics practitioner has to face the fact that many geological engineering and rock mechanics problems may be too complex to allow rigorous analysis but at the same time are deemed satisfactory for the construction of major structures. Ultimately, the geotechnical engineer or the engineering geologist has to express the effect of geologic factors in quantitative, even if approximate, terms and provide numerical data on strength and deformability of rock systems to be utilized in construction. Qualitative evaluations, quantitative descriptions of geologic features as such, and comparisons of specific test results are always of interest but may not suffice as basis for engineering decisions and designs. The present efforts of the rock mechanics group at the Karlsruhe University, Federal Republic of Germany, are based on a systematic combination of geomechanical models and numerical analyses based on the finite element approach. This group considers that at the present stage

Jan 1, 1970

By F. Weinberg

INTEREST is currently being directed toward grain boundary morphologies in zinc in terms of grain boundary facetingl and grain boundary energies.' Some years ago the present author attempted to measure grain boundary energies in 99.999 pct purity Zn as a function of boundary angle, using the standard procedure of measuring equilibrium angles of the boundary traces at triple points. This followed an investigation he carried out on preferential melting of |H (112) Fig. 1—Electron transmission micrograph of a stacking fault, grain boundary intersection in copper. GRAIN BOUNDARY STACKING FAULT Fig. 2—Schematic representation of the intersection of Fig. 1, indicating inclination angles 0 and trace angles $. specimens were prepared by the Bollman technique in an electrolyte of 70 pct methanol, 30 pct HNO3 main-tained at -30°C. The interfacial free energy of the high angle grain boundary and of the stacking fault is assumed to be thermodynamically equivalent to the corresponding in-terfacial tensions. In terms of the true dihedral angles & between the intersecting interfaces, the equilibrium of interfacial tensions in the direction parallel to the stacking fault yields: ysF = -ygb(cos F1+ cos ±cosF2) Here, ysF is the stacking fault free energy and ygb is the grain boundary free energy, assumed equal on both sides of the intersection. Forces acting normal to the grain boundary, of the form ??gb/?F,l are assumed negligible as the grain boundary remains straight for a considerable distance on either side of the intersection. The micrograph of Fig. 1 may actually consist of several closely spaced stacking faults on the same slip plane. The actual point of intersection between the grain boundary and the first stacking fault, and the equilibrium configuration of the intersection, should not be affected by the presence of the other faults, as

Jan 1, 1970

Factual data about the sedimentation in the Newcastle Coal Measures are presented. Data concerning the total coal measure sequence (isopachs, sand/shale ratio, and total coal thickness variation), data about three coal seams (Borehole, Dudley, and Victoria Tunnel) and data about interseam conglomerate units are discussed.From this data conclusions are drawn about the coal measure environment. The western edge of the coal basin, the Lochinvar Dome, although a high feature, was apparently stable during coal measure time. Despite its height it apparently supplied little sediment to the basin.The northern and north-eastern edge, which was unstable, supplied most of the coarse detritus (including the conglomerates) to the basin. The conglomerates show patterns of fluvial origin but after a period of "normal" variations in pattern they become restricted to two parallel zones evidently tectonically controlled. Deposition of conglomerates is episodic and separated by periods of coal formation when deformation was apparently slight. Formation of each of the three seams considered followed a rather similar pattern- each show development of thick coal around the basin edge and poor thin coal in the "axial" region of the present synclinal structure.Evidence of ill situ formation of some areas of the seams is discussed and periodic deformation of the basin during coal measure time is postulated.The unusual character of this coal basin, in particular the very coarse units, is stressed, despite the presence of many "normal "coal basin features.

Jan 1, 1970

By S. N. Singh, M. C. Flemings

Results are presented of a detailed study on the combined influences of ingot dendrite am spacing and thermomechanical treatments on the structure and solution kinetics of high --purity cast and worked 7075 alloy. Solution kinetics were found to depend sensitively on ingot dendrite am spacing and on details of therrnomechanical processing, including amount of reduction and extent of&apos; solution treatment before reduction. An approximate analysis is given for rate of solution of nonequilibrium second phase in the cast and worked structres; results of the analysis are compared with experiment. MICROSEGREGATION in high strength aluminum alloys manifests itself as "coring" (composition differences within the primary aluminum-rich phase), and as interdendritic second phase. The mechanism of formation of the microsegregation is understood, and approximate prediction of the amount of second phase is possible for simple binary systems.1,2 When alloy elements or impurities are present in amounts less than their solid solubility at solution temperature, any phases forming from these elements are termed "nonequilibrium" and can be dissolved by appropriate solution treatment. The rate at which the nonequilibrium phases are removed depends sensitively on their spacing (dendrite arm spacing in the cast material, or band spacing in wrought material). When alloy elements or impurities are present in amounts in excess of their solubility at the solution temperature, second phase particles form an "equilibrium" second phase that does not dissolve in heat treatment and may, in fact, coarsen in such treatment. Usual commercial, high strength, wrought aluminum alloys contain nonequilibrium second phases that were not fully dissolved during ingot processing. They also contain equilibrium second phases resulting from impurities present in amounts greater than their solubility. As has been shown by Antes, Lipson, and Rosenthal,3 and will be demonstrated further in a subsequent paper by the authors,4 significant improvements in mechanical properties of high strength alloys can be achieved by reduction or elimination of these second phases. Methods of elimination are 1) to employ high purity materials to minimize amounts of equilibrium second phase, and 2) to employ suitable thermomechanical processing techniques to fully eliminate nonequilibrium second phases. Work reported herein comprises a study of selected thermomechani- cal processing treatments, and of their influence on solution kinetics of wrought high purity 7075 alloy. EXPERIMENTAL PROCEDURE Melting and Casting. The bulk of the work reported was performed on a single ingot of high purity 7075 alloy. The ingot was 4 in. by 4 in. by 8 in. high, uni-directionally solidified following a procedure previously described.5 The mold was heated to 1350°F before pouring the melt. The bottom chill was carbon coated stainless steel. Water was circulated through the chill after the melt was poured. The 7075 alloy was prepared from high purity virgin material (aluminum, zinc, magnesium) and from master alloys (Al-50 pct Cu, A1-15 pct Cr, A1-5 pct Ti). Final measured melt composition (wt pct) was: Zn Mg Cu Cr Ti Fe Si Al 5.70 2.28 1.35 0.18 0.15 <0.002 <0.012 bal Melting was done in a silicon carbide crucible; all tools were coated with zircon wash to minimize iron contamination; degassing was by bubbling chlorine through the melt. che-rmomechanical Treatments. Detailed studies were made on material taken from a location approximately 13 in. from the chill and 51/2 in. from the chill (i.e., from 1 in. thick slices taken between 1 and 2 in. from the chill and between 5 and 6 in. from the chill). Solution treatment was done at 860°F in an air-circulating furnace with a "bottom drop" arrangement to achieve minimum delay time between solution treatment and quench. Samples solution treated in this way were 2 in. by 2 in. by 1 in. Temperature of the quench water was approximately 10°C. Mechanical reduction was by cold rolling. Samples 11/2 and 51/2 in. from the chill were treated for 12 and 24 hr, respectively, before cold rolling. Reduction by cold rolling was then 4/1, 16/1, and 35/1. In each case, several intermediate anneals (1/2 hr at 860°F) were used to permit reaching the final thickness without cracking; two such anneals were used for the 4/1 reduction, five for 16/1, and six for 35/1. After working, materials were again solution treated for various lengths of time from 0 to 48 hr and quenched in water. Structural Measurements. Secondary dendrite arm spacings were measured using procedures previously described.&apos; For each measurement reported, five photomicrographs were first made at X75. Measurements were made of dendrite arm spacings in at least 20 different grains (grain structure was equiaxed). Grain size measurements were made by running a number of random traverses across photomicrographs of the samples and obtaining the mean lineal intercept. Measurement of the volume percent of second phase and porosity was done by quantitative metallography. A two-dimensional systematic point count was used

Jan 1, 1970

By A. G. Jordan, W. Jeitschko, Paul A. Beck

The occurrence qf the V phase structure /Zr,Co,Ge, type) in ternary syste7ns (titanium, zivconium, niobium, lanta1urn) -(nickel, cobalt, iron)-(silicon, germanium) was incestigated. Nine V silicides and four V gertrlanides were found and their lattice constants are reporled. The lattice constants of twenty-one preri-ously identified E phases (TiNiSi type) are given. The average atomic volumes of these phases are discussed in relation to similar binary phases. ThE occurrence of a phase Ti4Ni4Si7 was first reported by Westbrook. DiCerbo, and peat&apos; who gave it the name "V phase". They also reported the existence of an E phase TiNiSi. Subsequently a systematic study was undertaken in this laboratory to explore the occurrence of E&apos; and V phases3 in related ternary systems. In the meantime the crystal structure of the E phase TiNiSi 4 and of the V phase Zr4CO4Ge 75,6 was determined. In the present paper the details of the V phase investigation and the lattice constants of the E and V phases are presented. V PHASES Alloy specimens of approximately 10 to 15 g were prepared by arc melting under argon (99.996 pct Ar) atmosphere. The starting materials were all of purity higher than 99.9 pct, with the exception of cobalt. which contained 0.14 pct Fe as the only major impurity. The weight losses were in all cases less than 2 pct, in most cases less than 1 pct. The samples were encapsulated in fused silica tubes with sufficient argon to yield about 1 atm pressure at the annealing temperature. After the homogenization anneal. Table I. the specimens were water-quenched. A representative portion of each specimen was then examined metallographically (etchant: 20 pct HNO,. 10 pct HF. 25 pct glycerine, 45 pct H20). Only minor amounts of second- and third-phase particles were observed in the specimens listed in Table I, with the exception of alloys Zr4Fe4Si7 and Ta,Fe,Si,. which contained an estimated 10 pct by volume of foreign phases. X-ray powder photographs were taken with a Seeman-Bohlin type focusing camera and Fe-KO radiation. Of the thirty possible combinations of elements in the ternary systems (titanium, zirconium. vanadium. niobium. tantalum)-(iron. cobalt, nickel)-(silicon. germanium) thirteen V phases could be identified. In the remaining seventeen ternary systems and also in the systems Cr-Ni-Si and (M0.W)-(Ni.Co)-Si no V phase was found at the composition 4:4:7 after annealing at temperatures between 900" and 1200&apos;C. For the determination of the lattice constants of the V phases Debye-Scherrer photographs were taken using the asymmetric film arrangement and CrKcr radiation (ka1, = 2.28962A). Using the positional parameters, as determined6 for Zr,Co,Ge,. Table 11. intensity calculations were carried out for each of the V phases with the aid of a computer program.: Thus unequivocal indexing of the diffraction patterns was greatly facilitated. The lattice constants. Table I. were then computed by a least-squares fit of the high-angle lines with f (0) = cos2 Q as extrapolation function. Only few. if any. very weak impurity lines were observed, with the exception of the three iron alloys Zr,Fe,Si7. Zr4Fe,Ge7. and Ta,Fe,Si7. The agreement

Jan 1, 1970

By J. L. Tomlinson, B. D. Lichter

Electrical resistivities 01 liquid Cd-Bi, Cd-Sn, Cd-Pb, In-Bi, and Sn-Bi alloys were measured using an electrodeless technique. The resistivities ranged from 50 to 160 microhm -cm, temperature dependences were positive, and no sharp peaks in the composition dependence of the resistivity were observed. On the basis of these observations, it was concluded that the alloys are typical metallic liquids. The electron con-cent9,ation was calculated from the measured resis-tizlity and available thermodynamic data using a model which attributes electrical resistivity to scattering by density and composition flzcctuations. A correla-tion was shown between the departure of the electron concentration from a linear combination of the pure component valences and the value of the excess integral molar free energy. Calculation of the temperature dependence of the electrical resistivity showed a need for more detailed thermodynamic data in these systems and led to suggestions for improvement in the concept of residual resistivity in the fluctuation scattering model. THE electrical resistivity of liquid metals provides information regarding interatomic interactions and their effects upon structure. In this experiment an electrodeless technique was used to measure the electrical resistivities of liquid alloys of Cd-Bi, Cd-Sn, Cd-Pb, In-Bi, and Sn-Bi, and the results were used with thermodynamic data to calculate a parameter which reflects the tendency toward localization of electrons due to compositional ordering. It was found that the resistivities of these alloys are generally metallic in magnitude and temperature dependence. The electrical and thermodynamic properties are discussed in terms of the fluctuation scattering model&apos;22 which supposes that the electrical resistivity arises from scattering due to a static average structure and departures from the average due to fluctuations in density and composition. Further, this model is compared with the pseudopotential scattering model of Ziman et al.3-5 EXPERIMENTAL PROCEDURES Alloy samples were prepared from 99.999 pct pure elements obtained from American Smelting and Refining Company (except tin which was obtained from Consolidated Smelting and Refining Company.) J. L. TOMLINSON, Member AIME, formerly Research Assistant Division of Metallurgical Engineering, University of Washington, Seattle, Wash., is now Physicist, Naval Weapons Center, Corona Laboratories, Corona, Calif. 0. D. LICHTER, Member AIME, is Associate Professor of Materials Science, Department of Materials Science and Engineering, Vanderbilt University, Nashville, Tenn. This work is based on a portion of a thesis submitted by J. L. TOMLINSON to the University of Washington in partial fulfillment of the requirements for the Ph.D. in Metallurgy, 1967. Manuscript submitted May 31, 1968. EMD Weighed portions were sealed inside evacuated silica capsules, melted, and homogenized before the resistivity was measured. The resistivity of a liquid alloy was measured by placing the sample inside a solenoid and noting the change in Q. According to the method of Nyburg and ~ur~ess,~ the resistivity of a cylindrical sample may be determined from the change in resistance of a solenoid measured with a Q meter as T7--5--W =R7JT^ =&apos;Kc-lm(Y) [1] where L, R, and Q = wL/R are the inductance, series resistance, and Q of the solenoid. The subscript s refers to the solenoid with the sample inside; the subscript 0 refers to the empty solenoid. Kc is the ratio of the sample volume to coil volume and y = 2 [bei&apos;0(br)-j ber&apos;o(br)~\ br\_bero(br) +j bei0 (br) expressed with Kelvin functions which are the real and imaginary parts of Bessel functions of the first kind with arguments multiplied by (j)3&apos;2. The argument of the function Y is hr where r is the sample radius and b2 = po~/p, i.e., the permeability of free space times 271 times the frequency divided by the resistivity in rationalized MKS units. Since Eq. [I] cannot be solved explicitly for p, values of Kc. lm(Y) were tabulated at increments of 0.1 in the argument by. A measurement of Q, and Q, determined a value of Kc . lm (Y) and the corresponding value of br could be read from the table. From the known r, uo,, and w, the resistivity, p, was determined. The change in Q was measured after letting the encapsulated Sample reach equilibrium inside a copper wire solenoid. The solenoid was contained in an evacuated vycor tube in order to retard oxidation of the copper while operating at high temperatures and heated inside a 5-sec-tion nichrome tube furnace capable of obtaining 900°C. Temperature was determined with two chromel-alumel thermocouples, one in contact with the solenoid 30 mm above the top of the sample and the other inserted in an axial well at the other end of the solenoid and secured with cement so that the junction was 2 mm below the bottom of the sample. Temperature readings were taken with respect to an ice water bath junction, and the voltage could be estimated to the nearest thousandth of a millivolt. The lower thermocouple was calibrated by observing its voltage and the Q of the coil as the temperature passed through the melting points of samples of indium and tellurium. The upper thermocouple reading was systematically different from the lower thermocouple reflecting the temperature difference due to a displacement of 60 mm axially and 6 mm radially. Calculations show that the gradient over the sample was less than 2 deg. Q was measured by reading a voltage related to Q from a Boonton 260A Q meter with a Hewlett Packard

Jan 1, 1970

By J. H. Swisher, E. O. Fuchs

Rate equations were derived to describe the kinetics of internal oxidation of cylinders and spheres. The derived equations for cylinders were checked experimentally by means of sub scale thickness and electrical conductivity measurements on Cu-Cr alloy wires. The properties of the internally oxidized samples were examined with conductivity applications in mind. It was possible to produce uniform dispersions of Cr2O3 in copper with an initial chromium content as high as 3 wt pct. While electrical conductivities only a few pct less than that of OFHC copper were obtained, the Cr2Os particle size and spacing were too large for effective dispersion hardening. T.HE process of internal oxidation has been used widely in basic studies of the permeability of gases in metals. In a review article, Rapp1 has discussed the principles of internal oxidation in considerable detail. From a technological standpoint, internal oxidation is often considered undesirable, since it is a means by which inclusions can be introduced into an otherwise clean material. Another important aspect of internal oxidation is its use as a means of dispersion hardening a material. Broutman and Krock2 discuss this and other methods for making dispersion hardened alloys. The only internally oxidized material known to the authors which is commercially available is a Cu-BeO alloy.3&apos;4 This alloy is made from Cu-Be alloy powder, using a so-called Rhines pack. It has a tensile strength of 80,000 psi and retains its strength at relatively high temperatures. The objectives of the present study were to derive rate equations for the internal oxidation of cylinders and spheres, to check the derived equations for cylinders experimentally, and to examine the structure and properties of internally oxidized Cu-Cr alloys. The Cu-Cr system was chosen for this study because uniform dispersions are obtainable at high alloy contents, which is a desirable characteristic in dispersion hardened materials. RATE EQUATIONS FOR VARIOUS GEOMETRIES A number of authors5--9 have derived equations to describe internal oxidation kinetics. These derivations differ somewhat in mathematical assumptions and approximations, and all except one of the derivations deal exclusively with the internal oxidation of plates. The exception is a brief treatment of cylindrical and spherical geometries given by Meijering and Druy-vesteyn9 as a part of a comprehensive paper on the general subject of internal oxidation. These authors did not obtain rate data to check their derivations, although they did show that the hardness profile across an internally oxidized sample is directly related to the rate of interface movement. For cylindrical and spherical geometries, a quasi-steady-state approximation is needed to circumvent mathematical complications in obtaining a solution to the basic differential equations. In using this approximation, we consider the concentration gradient of dissolved oxygen in the internally oxidized zone or sub-scale to be the same as the gradient which would be present if there were no movement of the subscale interface. The steady-state approximation introduces an error of about 1 pct in computing the rate of internal oxidation of an Fe-1.0 pct Mn alloy plate, if the present method is compared to the more exact method of Wagner.7&apos;10 The details of the derivations of the rate equations for cylinders and spheres are given in the Appendix, and only the results of these derivations are given below. The final equations obtained by Meijering and Druyvesteyn9 can be shown to be equivalent to our Eqs. [1] and [2], although the two approaches are somewhat different. Cylindrical Geometry. [2] where r1 is the outer radius of the cylinder or sphere, cm, r2 is the radius of the unreacted core, cm, see Fig. l(a), D is the diffusion coefficient of oxygen in copper, cm2 per sec, %O is the concentration of dissolved oxygen at the surface of the specimen, wt pct, %Cr is the initial chromium concentration in the alloy, wt pct, and t is the reaction time, sec. Plate Geometry. The analogous rate equation for a plate has been derived previously for internal oxidation of Fe-Al alloys.8&apos;11 For Cu-Cr alloys, we may write the same equation as follows: [3] where r1 is the half-thickness of the plate, cm, and r2 is the distance from the mid-plane to the subscale intherate is An analysis of Eqs. [1], [2], and [3] shows that for a plate the rate is completely parabolic. The initial

Jan 1, 1970

By Norman J. Sather

LOCATION AND HISTORY The Bunker Hill Mine is situated on the south side of the Coeur d’Alene River in Shoshone County of Northern Idaho near the City of Kellogg. Kellogg, the largest in the Coeur d’Alene District cities, is at an elevation of 2,300 feet and has a population of approximately 7,000 people. It can be reached by air, railway or highway. The history of the Bunker Hill Mine dates back to August 26, 1885, when Noah S . Kellogg found the outcrop of the Bunker Hill ore body on the hillside above the present town of Wardner, Idaho, in Milo Gulch. A small concentrator was erected in 1886. Before the railroad came, the mine output was transported by mule teams to the head of navigation on Coeur d’Alene Lake. After ten years of production, an interest was purchased in the Tacoma Smelter at Tacoma, Washington, to which the entire output was shipped. In 1916 and 1917 a modern lead smelting plant and refinery was erected and in 1927 and 1928, a modern Electrolytic Zinc Reduction Plant was built and put into operation by the Sullivan Mining Company which was 50% owned and now totally owned by The Bunker Hill Company. GEOLOGY AND MINERALOGY The Bunker Hill ore bodies are found in gray and greenish gray quartzite and argillaceous quartzite of Precambrian age and are known as the Revett and St. Regis formations. Most of the ore bodies are found in the St. Regis formation.

Jan 1, 1970

By H. B. Bell, P. C. Lidster

A study has been made of the use of ThO2-Y2O3 solid electrolytes to determine activity of chromium in Fe-Cr and Ni-Cr alloys in the temperature range 1300° to 1700°K. This method has been shown to give results which agree with the best vapor pressure measurements. SEVERAL investigations1"5 have been made of chromium activities in Fe-Cr alloys. Most of these have been made by vapor pressure measurements using knudsen cell techniques while one has been made using gas equilibration with H2/H2O gas mixtures. In the present investigation electromotive force measurements have been made on this system using a thoria yttria solid electrolyte. This system was -chosen to establish the technique of measurement at low oxygen potentials, before extending it to Fe-Ni-Cr alloys. The cell used was Pt Cr • Cr2O3 ilThO2 • Y2O3 llalloy • Cr2O3 IPt Since the oxygen pressure of the chromium-chromic oxide mixture lay in the range 10"19 to 1027 atm in the temperature range investigated, thoria yttria electrolytes were used. It was soon found during the investigation that considerable care was required to prepare satisfactory electrolytes and a study was made to find the best method of preparing pellets of TI1O2-Y2O3 solid solution of as near theoretical density as possible. Various compositions in the range 2 to 15 mole pct Y2O3 were studied but the experimental measurements were made with electrolytes containing 4 to 5 pct Y2O3. The method of preparation finally adopted was to use thorium oxalate and yttria as raw materials. The thorium oxalate was decomposed at 900°C for 6 hr to give a reactive powder. This powder was then mixed with the appropriate amount of yttria and ground in an agate mortar for about 4 hr. The powder was moistened with absolute alcohol as a lubricant and pressed in a metal die at a pressure of 7 tons per sq in. The pellets were then heated at 1100°C for 24 hr followed by 24 hr at 1250°C. After this firing cycle the material was reground and repelleted and again fired at 1100° and 1250°C followed by heating for 7 days at 1600°C. It was found in later experiments that a further firing of 4 hr at 2000°C improved the density further and gave pellets of only 2 pct porosity. After firing, the pellets were polished on emery paper and finally with the 2 µ diamond paste. The polishing was followed by a final firing of 24 hr at 1500°C. Investigation showed that this final treatment minimized reaction between the electrolytes and chromium oxide. It was believed that this was because of a lowering of the surface energy of the electrolyte surface. Two types of investigation were carried out to check that the pellets were satisfactory oxygen ion elec-

Jan 1, 1970

By Freeman Bishop

Copper production has been under Government scrutiny for many years because it&apos;s known as a concentrated industry which in turn creates what many economists label administrative prices. Neither of these conditions is illegitimate, per se, the Federal Trade Commission and the Justice Department have said time and again. But Justice spoke up once more. This time over a Puerto Rican copper development planned by American Metal Climax, Inc., and the Kennecott Copper Corp. Bureaucratic Dichotomy Creates Confusion and Conflict In the Copper Industry Ian MacGregor, chairman and chief executive officer of Amax, said Justice in a recent communique questioned the propriety of the proposal of a joint copper venture in Puerto Rico. At the same approximate time, Dr. Hendrik S. Houthakker, chairman of the President&apos;s Commission on Copper, was urging copper producers to expand production to help hold down prices by making more copper available to all consumers. This, Mr. MacGregor said, is creating confusion and conflict, since the Administration from one source is chastising the industry for doing what another branch requests.

Jan 1, 1970

By J. Kittl, D. Arias

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

Jan 1, 1970

By O. N. Carlson, D. G. Alexander

THE hardness anisotropy of metals and alloys has been of increasing interest in recent years but silicon ferrite,1 niobium,2 and tungsten3,4 are the only bcc metals about which this type of information has been reported. This investigation was carried out on vanadium and chromium single crystals in an effort to determine to what degree the hardness variations observed in these metals are due to orientation effects and to compare their behavior with other bcc metals. In earlier work the authors had observed a small angular dependence in the Diamond Pyramid Hardness of single crystalline vanadium on the (100) plane but no anisotropic effects were noted on either the (110) or (111) planes. At the suggestion of R. G. wheeler5 it was decided to investigate this effect in greater detail using the more asymmetric Knoop indentor. The vanadium metal used in the study was prepared by the aluminothermic reduction of V2O5 followed by electron beam melting.6 The principal analyzed impurities were 230 ppm C, 230 ppm O, 65 ppm N, 90 pprn Al, Cr not detected, 50 ppm Fe, 60 ppm Ni, and 200 ppm Si. The chromium was an iodide-refined product obtained from the Chromalloy Corporation. Analysis of this material showed the following amounts of impurities present: 10 ppm C, 9 ppm O, 2 ppm N, 0.4 ppm H, 3 ppm Al, 2 ppm Ca, 2 ppm Cu, 20 ppm Fe, 1 ppm Mg, 0.3 ppm Mn, 1 ppm Mo, 3 ppm Ni, 10 ppm Si, and 1 ppm V. Single crystals of both metals about 1 cm in diam and 10 cm in length were grown by an arc-zone melt- ing technique.7 The chromium crystal was annealed at 1600°C for 6 hr in a purified argon atmosphere to remove any strains or inhomogeneities, but the vanadium was tested in the as-grown condition. The crystals were oriented by the Laue back-reflection method and then sectioned with a spark cutter into individual specimens with a (loo), (110), or (111) plane parallel to the crystal surface. They were mounted in Lucite and carefully ground to a flat surface. The vanadium specimens were then electropolished in a 6 pct perchloric acid-methanol mixture while the chromium specimens were mechanically polished on a Syntron vibratory polisher using an alumina abrasive. The orientation of each crystal was then rechecked by the back-reflection X-ray method. All of them were found to lie within 2 deg of the desired orientation with the exception of the (110)-Oriented chromium crystal which was within 4 deg. Microhardness impressions were taken at 10 deg intervals from the common (110) direction by rotating the crystal in the plane of the crystal surface. A Knoop indentor was used with a 400-g load on the vanadium crystals and an 800-g load on the chromium. The hardness values are averages of 6 impressions and standard deviations were calculated for each set of data. The values reported for the (111) plane of vanadium are based on from 10 to 15 measurements for each point. The microhardness results for vanadium and chromium are plotted as a function of the angular rotation of the long axis of a Knoop indentor from the (110)

Jan 1, 1970

By J. Douglas Gibson

In Canada, the economic climate for mining is still warm, but a noticeable chill set in last November when the Government published a White Paper on tax reform known as the Carter Report. Moreover, this chill could drop to a freeze injurious to the whole Canadian economy if two of the proposals in the Carter Report are adopted. The offending suggestions call for an end to (1) the depletion allowance and (2) the three-year tax holiday for new mines. Both of these tax incentives have played a major role in the postwar development of the Canadian economy and will, if undisturbed, play an even more important role in the future. The fact that they have worked and worked well is evident from the record. Fruits of an Industrial Beanstalk Excluding fuels, the value of Canadian mineral production was just under $3 billion in 1968-almost nine times as much as in 1946. With fuels included, the figure is $4.25 billion, or almost ten times as much as in 1946. Proportionately, this growth far exceeds that of Canada&apos;s manufacturers or of her economy as a whole. Table I traces the overall mineral production growth by principal products. Of particular interest here are petroleum, iron ore, natural gas, sulfur and potash, the combined production of which has grown from little or nil to a point where it now accounts for more than 40% of Canada&apos;s mineral output.

Jan 1, 1970

By George Steintveit

Det Norske Zinkicompani A/S was established in 1924, on the initiative of the Compagnie Royale Asturienne des Mines. Experimental electrothermic zinc production was carried out on industrial scale for a two-year period, but the problems of electrothermic smelting were not solved. A license for the electrolytic zinc production process was then obtained from the Anaconda Copper Mining Co. A plant for electrolytic zinc production was built, near the small fjord town of Odda in Hardanger, West Norway, The production was based on zinc ore from Spain, and cheap local hydro-electric power. The plant came into operation in 1929. Annual capacity, 36,000 tons. In 1964 a long-term agreement was concluded with Boliden AB by which Det Norske Zinkkompani is secured the raw materials basis for an expansion of the annual capacity to 100,000 tons of zinc, Since World War II, the company has been pursuing extensive research and development programs. As a result, various sections have been rebuilt: nev unloading and storage facilities, a 250 ton per day Fluid Bed Roaster with contact plant, new continuous leaching system, integrating the Jarosite Residue Process, new solution purification section - upgrading the solution quality for a 600 Amp/m2 current density Tank Room operation -, installation of induction furnaces for cathode melting with casting machines and automatic stacking of slabs. Simultaneously, instrumentation, and methods of automatic control have been developed and introduced, providing conditions for optimal plant operations.

Jan 1, 1970

By K. F. Clark

Some 30 years ago Stevenson (1940) underscored the fact that most of the world&apos;s molybdenite production came from the Cordillera that comprise the western part of North America, and that the northern extension of the Cordillera into British Columbia is not essentially dissimilar to the United States section. Therefore, in view of the successful development of molybdenite resources in the United States, he concluded that prospecting in the Canadian section f the Cordillera should be encouraged. However, as recently as seven years ago Schneider (1963) remarks that no large economic deposits have been brought into production in British Columbia, although one important property was being evaluated. World production f molybdenum ore was sporadic until 1900. Among the very early producing areas in North America were Arizona and New Mexico in the United States. World War I provided the stimulus that brought the Climax deposit into production, and in 1920 Questa, New Mexico followed, although the ore came from fissure vein deposits at that time. In the early part f this century high grade deposits in various parts f the world containing 5-20 percent MoS2 were exploited. In Canada most production during World War I came from Quebec and Ontario. With the build-up of world tension and the inception f hostilities in 1939, British demand was satisfied by United States producers (Schneider, 1963).

Jan 1, 1970