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By Andrew Fletcher

AS good health is the most important asset in life, the development of healthful conditions should be the one common meeting ground of agreement between management and labor. Health should not be a subject to be pulled apart, shoved around, or bargained about. Differences of opinion may exist in the procedure and techniques employed in approaching the goal of maintaining the health of workmen, and in the method of increasing the ultimate profit of the employer by improved working and living conditions. Such matters are doubtless appropriate subjects for discussions between the interested parties, but techniques are only tools. If an employer fails to remedy a hazard or a menace which contributes to poor working condlions, this constitutes a legitimate grievance. It should not be necessary, however, nor is it desirable that fundamentals of health maintenance become matters of collective bargaining, any more than should the principles of management and engineering. I have been especially concerned during the last few months with the propaganda in collective bargaining negotiations throughout the country for including in union contracts a given number of days of sick leave with pay. We all

Jan 1, 1946

By H. Biloni, G. F. Bolling

The microsegregation in tin specimens containing 0.2, 0.5. or 1 wt pct Pb has been studied m detail. The specimens were grown from the melt in a controlled fashion and exhibited a well-developed cellular substructure. In general, a severe microsegre-gation can be observed in all the photomicrographs presented. Some observations of special interest are: the distribution of a second phase, the presence of a eutectic in several forms, the evidence for dif- THE Smialowski or cellular substructure which forms during solidification has been extensively studied during the past decade.'* Many of the im- *Most references to the cellular substructure except for the last 2 years are reviewed by Winegard.' portant characteristics of this substructure, such as its occurrence and variability with growth conditions, its association with the phenomenon of constitutional supercooling, and its effect on dislocation production and mobility, have received quantitative fusion of solute in the solid, and the enhancement of segregation at a dislocation subboundary network ("striations"). On the basis of the metallographic observations, it can be deduced that the segregation observed is representative of the solute segregation produced during crystal growth. Some deductions are also made about the interplay of the two substructures, cells and striations, and about the mode of cellular growth. investigation both experimentally and theoretically. However, the concentration profile of the solute segregated during crystal growth has not been examined in detail. Tin crystals grown from melts containing various concentrations of lead have been most extensively studied. In a recent investigation of Sn-Pb alloys, Kramer et a1.2 were able to measure the effective solute distribution coefficient, k,, at the most advanced points of the solid-liquid interface, over a large range of growth conditions, finding it to approach the value of k,, the equilibrium distribution coefficient. As will be shown, this must lead to drastic segregation. Another recent study of several Sn-Pb alloys was made by Plaskett and winegard3 who investigated the variation of growth conditions

Jan 1, 1963

By Maurice Ewing, J. A. Peoples, J. W. Peoples, A. P. Craby

The purpose of this paper is to present the results of the application of the earth-resistivity method of subsurface investigation to the problem of locating seams of anthracite coal beneath a mantle of soil and subsoil. Details are given of the successful use of this method in locating the outcrops of anthracite seams in actual prospecting. The presence of the outcrop of an anthracite seam is indicated at points where electrical resistivity tests showed relatively low readings. The reason for this is that in some localities the resistivity of anthracite was found to be about 0.0001 megohm-cm. compared to 1 to 200 megohm-cm. for shales and sandstones. For two reasons it is believed that the data summarized in this paper should be of particular interest. In the first place, most of the interpretations of the resistivity survey have been checked by subsequent drilling and some by the removal of the overburden and the exposing of the anthracite seams. It is infrequent that the opportunity for checking results so thoroughly is given. In the second place, the fact that recent commentatorsl,2,3 on the application of geophysical methods to mining have concluded that direct prospecting for anthracite and other types of coal is not promising makes the good results obtained more significant. So far as the authors can learn, the only previous experiment with electrical methods in the Pennsylvania anthracite field was one made by Sherwin F. Kelly in 1921, when he used the self-potential method at Wilkes-Barre4. The profile he made does not show a very marked correlation with the geologic cross section. Kelly points out that stray currents from electric motors in the mines undoubtedly affected 'his results, but the experience of the present authors with stray currents from mining machinery suggests the possibility that the potentials measured by Kelly were due almost entirely to this effect.

Jan 1, 1936

By Maurice Ewing, A. P. Craby, J. W. Peoples, J. A. Peoples

The purpose of this paper is to present the results of the application of the earth-resistivity method of subsurface investigation to the problem of locating seams of anthracite coal beneath a mantle of soil and subsoil. Details are given of the successful use of this method in locating the outcrops of anthracite seams in actual prospecting. The presence of the outcrop of an anthracite seam is indicated at points where electrical resistivity tests showed relatively low readings. The reason for this is that in some localities the resistivity of anthracite was found to be about 0.0001 megohm-cm. compared to 1 to 200 megohm-cm. for shales and sandstones. For two reasons it is believed that the data summarized in this paper should be of particular interest. In the first place, most of the interpretations of the resistivity survey have been checked by subsequent drilling and some by the removal of the overburden and the exposing of the anthracite seams. It is infrequent that the opportunity for checking results so thoroughly is given. In the second place, the fact that recent commentatorsl,2,3 on the application of geophysical methods to mining have concluded that direct prospecting for anthracite and other types of coal is not promising makes the good results obtained more significant. So far as the authors can learn, the only previous experiment with electrical methods in the Pennsylvania anthracite field was one made by Sherwin F. Kelly in 1921, when he used the self-potential method at Wilkes-Barre4. The profile he made does not show a very marked correlation with the geologic cross section. Kelly points out that stray currents from electric motors in the mines undoubtedly affected 'his results, but the experience of the present authors with stray currents from mining machinery suggests the possibility that the potentials measured by Kelly were due almost entirely to this effect.

Jan 1, 1936

By Robert L. Akre

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

Jan 6, 1976

By J. L. Tokich, A. R. Troiano

INTRODUCTION SINCE 1921, when Hull' discovered that cobalt can exist in the face-centered cubic and hexagonal close-packed modifications, the transitions that occur in cobalt have been extensively studied. It is generally agreed that on heating the hexagonal lattice changes to the cubic structure at temperatures ranging from 400 to 500°C although considerable doubt exists as to the exact temperature. Data concerning the temperature of the transformation on cooling are much less concordant and their interpretation has not been satisfactory. The study is further complicated by the fact that many investigators have reported the existence of a high temperature allotropic change in the range 850 to 1020°C, at which the cubic lattice reverts to the hexagonal modification. The transition on cooling, which has been reported as occurring at various temperatures from approximately 400 to 100°C, is of particular interest. Troiano and Greninger2 have recently suggested and considered the possibility of allotropic transformations occurring in pure metals by a shear-type, diffusionless (martensite) transformation. The case of cobalt was specifically discussed and certain observations of previous investigators evaluated in terms of this type of transformation. Table 1 briefly outlines the methods and results of previous investigators of the transformation temperatures of cobalt. MATERIALS AND METHODS The major portion of this investigation was performed with cobalt sheet containing a total of 0.2 pct impurities with carbon present to the extent of 0.1 pct. After melting in an induction furnace under an atmosphere of hydrogen, the carbon content analyzed 0.03 pct. Some observations were repeated with hydrogen reduced cobalt compresses analyzing 99.9 pct pure. No significant variations in results were observed employing the as-received sheet, the remelted stock, or the cobalt compresses. Filings for X ray diffraction analysis were sealed in evacuated glass ampoules. Pyrex glass tubing was used for temperatures below 600°C and for higher temperatures clear fused quartz was satisfactory. After appropriate heat treatment at various temperatures, the specimen ampoules were furnace cooled, air cooled or quenched by crushing under distilled water. This allowed a range of cooling velocities from less than one degree C per sec to greater than 1,000°C per sec. X ray diffraction patterns were taken with a Debye camera and filtered characteristic cobalt K-alpha radiation. The proportion of the existing phases was roughly approximated by visual examina-

Jan 1, 1948

By Theo B. Comstock

TO the large majority of visitors the unique features of the National Park are interesting chiefly on account of their novelty. Scientists of all schools may find here food for reflection, and much that is rare and marvelous; but the real, practical uses of the reservation, aside from its pleasure-giving adaptations, are not as yet fully appreciated. Since 1873, the writer has on frequent occasions expressed freely his own views upon the proper means of utilizing the Park for the best interests of science.* Some of the recommendations made have been adopted by the authorities. At the suggestion of friends I present here a brief statement of facts concerning matters which may be of advantage for visiting engineers to know, hoping that the very limited stay of the Institute may thereby be rendered a little more profitable, and that our common profession may possibly receive some benefit. First, then, it should be understood that, as in many other cases in. the West, the present routes to the Park from the south are not the most direct. The expedition of Captain (now Major) Jones in 1873 discovered a practicable route for a, wagon or railroad via the head of Wind River, through To-gwo-tee Pass and Two-Ocean Pass, by which the distance from Point of Rocks, Wyoming, on the Union Pacific R.R., to the Yellowstone Lake, is only 290 miles. Eventually, it is probable that a railway line from Cheyenne or some other point in Wyoming will be constructed, which, taking advantage of

Jan 1, 1888

By A. J. Ardell, O. D. Sherby

The elevated-temperature steady-state creep behavior of polycrystalline a Zr was studied in vacuo under constant tensile stress. The experiments were conducted from 660° to 845°C over the stress range 870 to 5400 psi. The steady-state creep rate, is, of a Zr was found to be related to the applied stress, a, and temperature, T, by the equation where C is a constant. Two interpretations of the data are considered, each requiring different values of the parameters ß, Q, and . It is shown that this formula can be derived using Gilman's phenomeno logical equation relating dislocation velocity to the shear stress for the case where dislocation mobility is limited by the nucleation of kink motion. From the fundamental dependence of strain rate on dislocation velocity and the density of mobile dislocations, the factor exp(ßo) can be related to the stress dependence of the dislocation density, and Q to the energy of kink formation. The two interpretations considered are as follows: Case I—the parameters are adjusted so that the equation above describes the data over the entire range of stress and temperature, implying that creep is controlled exclusively by dislocation glide; Case IIthe parameters are adjusted to allow for the possibility that creep is diffusion-controlled at high stresses but glide-controlled at low stresses. For both cases the values of the parameters are within the spread permitted by the data. Factors favorable to the observation of the unusual stress -dependence of i, for a Zr are discussed and it is shown that the anomalously rapid rates of self-diffusion and the low modulus on the principal glide system are primarily responsible for the anomalous creep behavior. Metal-lograflhic observations are presented and discussed with reference to the overall creep behavior. PREVIOUS investigations of the creep behavior of a Zr have been conducted from room temperature to about 500C The results of these investigations are primarily of engineering significance because of the variety of conditions under which they were carried out, and the low testing temperatures employed. Little information is available concerning the fundamental nature of the elevated-temperature creep behavior of a Zr. This investigation of the creep behavior of a Zr above half the melting temperature (the melting temperature, T,, of a Zr is estimated to be about 1860"K was initiated because there are two significant anomalies of the physical properties of a Zr: a) the rate of self-diffusion in polycrystalline a Zr is anomalously rapid: b) both Young's modulus for polycrystalline a Zr and the shear modylus as-sociated with the prismatic slip system { 1010)( 1120) (the principal slip system in a Zr 7) have anomalously large temperature variations The importance of these quantities to the understanding of creep behavior has been demonstrated, and it was hoped that this investigation would provide a critical test of the predictions based upon the analysis of creep data for other pure metals. However, as the investigation progressed it became increasingly clear that the unusual creep behavior of a Zr could not be analyzed in a conventional manner. 1) EXPERIMENTAL EQUIPMENT AND PROCEDURES Two grades of zirconium, designated A and B, were used in this investigation. The analyses, as supplied by the vendors, are presented in Table I. Material A, with a nominal purity of 99.84 pct, was supplied by the Wah Chang Corp. in the form of cold-rolled sheet from which specimens were machined without further fabrication. Material B, with a nominal purity of 99.95 pct, was purchased from the Nuclear Materials and Equipment Corp. in the form of iodide crystal bar.

Jan 1, 1968

By Rex O. McLellan

The formation of a monovacancy in a metal is simulated in an elastic model by the displacement of the surface of a small spherical cavity in a large elastic continuum. The application of linear elasticity to this distortion results in a well- known formula for the energy and an expression for the concomitant entropy change due both to the shear strain in the continuum and also to the dilation of the solid resulting from the boundary conditions at the surface of the solid. Elastic data (the sliear modulus and its temperature coelficient) are used to calculate the entropy and energy of formation for many metals. Despite the simplicity of the assumptions involved, the agreement between the calculated entropies and energies and experimental values is remarkably good. In recent years there has been a large increase in measurements of the absolute concentration of mono-vacancies in metals as a function of temperature. Hence new data for both the energy and the noncon-figurational entropy of formation of monovacancies has become available. Recent measurements&apos; of the anomalous (non-Arrhenius) self-diffusion in many bcc metals has also focused interest on the prediction of the thermodynamic parameters of mono- and multi-vacancies in those metals for which no data are available. Damask and Dienes&apos; have discussed the various theoretical calculations of the energy of formation EL, of a monovacancy. These include simple models involving the breaking of atomic bonds on moving atoms from the interior of a crystal to the surface, models combining elastic calculations with surface-energy terms and detailed quantum mechanical calculations. The simler models give the correct order of magnitude of &, but tend to overestimate it by a factor of about two. The quantum mechanical calculations4"7 have been carried out for the noble and alkali metals with generally reasonably good agreement with the available Ef data. The calculation of entropy of formation Sfv14 lnvolves a fundamental calculation of the perturbation of the phonon spectrum caused by the creation of a vacancy. Huntington, Shirn. and wajda8 have given an approximate evaluation of sJV by considering an Einstein model for the localized vibrations in the immediate neighborhood of the defect and then using elastic theory to calculate the entropy associated with the shear stress field in the distorted crystal (as originally proposed by Zenerg). They also included a term due to the dilation of the crystal. They obtained a value of 1.47k for copper, in good agreement with the experimental value (1.50k). However, Nardelli and Tetta- manzi1° have recently shown that neglecting the coupling between atoms (Einstein Model) may lead to a serious error so the agreement may be somewhat fortuitous. In this work simple linear elastic theory is used to calculate the entropy and energy of formation of mono-vacancies. Despite the simplicity of some of the assumptions involved, the agreement with the available experimental data is remarkable. However. the reasonable degree of success in the application of linear elastic calculations to the excess entropy of a solute atom in a dilute solid solution1&apos; indicates that the application of elastic theory to vacancies. where the interaction of different atomic species is not involved, may not be inappropriate. THE ELASTIC MODEL The metal is assumed to be a spherical elastic continuum. A small spherical cavity of volume V = 4i;v:&apos;/3 is cut from the center. removed. and dissolved rever-sibly in the bulk of the material. TO a good approximation no net atomic bonds are broken and the material does not undergo a volume change although the externally measured volume of the body would increase by V. The radius of the sphere of metal is much larger than r Next a negative pressure is applied to the cavity causing its surface to be displaced inward by an amount simulating the relaxation of the lattice around a monovacancy. In this model the energy and entropy accompanying the distortion are taken as 4, and <. As a first approximation the equation of state for the solid is taken as: r = ro(i + *~D LiJ where K is the bulk modulus. P the hydrostatic pressure. Vo the volume of the material at 0°K and zero pressure. and d+/dT = 30. where 0 is the linear thermal expansion coefficient. The variation of entropy with hydrostatic pressure is given by the Maxwell equation: These equations give the entropy change resulting from increasing the hydrostatic pressure from 0 to P as: and since • we have: This is the entropy arising from the dilation resulting

Jan 1, 1970

By W. D. Forgeng, D. Beregekoff

In the routine examinatlion of a wide variety of metal specimens it is sometimes necessary to have special methods of polishing in order to retain and reveal certain details in each specimen. Among such special cases is the retention of graphite in malleable and gray cast irons, the preservation of all types of non metallic inclusions in both hard and soft steels, obtaining a scratch-frec surface with soft metals, and avoiding the usual relief effects with very hard specimen. such as tool metals c3o1ltaining various carbide and nitride phases. It, is the purpose of this paper to give an account of some of these special polishing methods in use at the Union Carbide and Carbon Research Laboratories. The polishing procedures outlined have been found to give uniform results. It is obvious that only general rules and the most important working details can be given here. Following these rules, the polisher can obtain satisfactory results if he possesses the necessary patience and has a sincere desire to give as nearly perfect a finish as possible to his work. Procedure The specimen is flattened with considerablecare on a file or sharp cutting sanding belt, since the initial production of a flat surfacc greatly facilitatcs subscqucnt polishing. The polishing motors have two speed., 600 and 1200 r.p.111. ,It higher speeds specimens arc likely to he over-Ileated, therefore the high speed is used only when a saving of time is important. The following abrasive papers are used consecutively: Yo. 2, So. 1, No. 0, No. 00 and No. 000. The final wet polishing is done oil a cloth-covercd metal disk. Woolen broadcloth of the best quality and capable of resisting severe pressure is most commonly used on the last lap. . polishing felt of the type used for polishing optical glass has been found equally satisfactory and is much stronger than broadcloth. For retaining inclusions and graphite, a hard cloth with very little residence, such as

Jan 1, 1939

By D. Beregekoff, W. D. Forgeng

In the routine examinatlion of a wide variety of metal specimens it is sometimes necessary to have special methods of polishing in order to retain and reveal certain details in each specimen. Among such special cases is the retention of graphite in malleable and gray cast irons, the preservation of all types of non metallic inclusions in both hard and soft steels, obtaining a scratch-frec surface with soft metals, and avoiding the usual relief effects with very hard specimen. such as tool metals c3o1ltaining various carbide and nitride phases. It, is the purpose of this paper to give an account of some of these special polishing methods in use at the Union Carbide and Carbon Research Laboratories. The polishing procedures outlined have been found to give uniform results. It is obvious that only general rules and the most important working details can be given here. Following these rules, the polisher can obtain satisfactory results if he possesses the necessary patience and has a sincere desire to give as nearly perfect a finish as possible to his work. Procedure The specimen is flattened with considerablecare on a file or sharp cutting sanding belt, since the initial production of a flat surfacc greatly facilitatcs subscqucnt polishing. The polishing motors have two speed., 600 and 1200 r.p.111. ,It higher speeds specimens arc likely to he over-Ileated, therefore the high speed is used only when a saving of time is important. The following abrasive papers are used consecutively: Yo. 2, So. 1, No. 0, No. 00 and No. 000. The final wet polishing is done oil a cloth-covercd metal disk. Woolen broadcloth of the best quality and capable of resisting severe pressure is most commonly used on the last lap. . polishing felt of the type used for polishing optical glass has been found equally satisfactory and is much stronger than broadcloth. For retaining inclusions and graphite, a hard cloth with very little residence, such as

Jan 1, 1939

By Mark Sheppard

DURING the winter of 1937, the writer visited a West Virginia stone, quarry at which the overburden is stripped hydraulically. The quarry is in a bed of limestone, about 200 ft. thick, which outcrops on a hillside above a small river; the quarry face is 175 ft. high. The top of the stone is cut in all directions by erosion channels, which are filled with a tough, red clay. Some of the larger channels are 30 ft. deep and 8 ft. wide, The thickness of the clay overburden ranges from a few inches to 10 ft., the average being estimated as less than 3 feet. The topography of the district is rugged, and the hillside above the quarry face is not suited to the use of the usual mechanical methods of moving dirt. Until hydraulicking was started 10 years ago, the over-burden was dug by hand labor, dumped to the quarry floor and trans-ported to the dump in quarry cars, Cleaning deep channels was a slow and expensive process. When hydraulicking was started, the top of the quarry face was over 200 ft. above the level of the river. The pipe line was carried in a semi-circle around the top of the quarry about 200 ft. from the face and about 50 ft, above it. As there is no adequate supply of water above the quarry, the water must be pumped from the river: As quarrying pro-gressed the pipe line was moved until the discharge points are now over 300 ft. above the river. Water is pumped from the river by a four-stage centrifugal pump having a 5-in. intake and a 4-in. discharge. It is direct-connected to a 200-hp,, 2300-volt, 1760-r.p.m. induction motor. At 1760 r.p.m. the rated capacity of the pump is 750 gal. per minute under a head of 600 ft. The pump is installed in a house of frame construction on the river bank, about 10 ft, above normal water level, which also houses the pump for the mill-water supply. Above the pumps are hoisting hays into which the motors are raised whenever the river reaches flood stage.

Jan 1, 1938

By J. K. Brooke, F. A. Renninger

During 1966, crushed stone production in the United States totaled just over 811 million tons valued at almost $1.2 billion. This represented in- creases of 4 % in tonnage and 5 % in value over that for 1965. Excluding the crushed stone used for agricultural and certain industrial purposes (cement, lime and flux), crushed stone mineral aggregate production totaled 616.3 million tons valued at almost $910 million, also up roughly 4% in tonnage and 5% in value over the 1965 figures. Limestone was by far the most widely used rock variety, followed by basalt, granite and sandstone in that order. Concrete aggregate and roadstone continued as the main uses for stone, accounting for 63% of all tonnage produced in 1966 and 60% of total stone value. Sand and gravel production in 1966 increased 3% over that for 1965. Total 1966 output was just in excess of 934 million tons valued at almost $985 million as compared with 908 million tons at $957 million for the previous year. Excluding the higher valued industrial sands, 903.2 million tons of sand and gravel valued at $891.6 million were used directly as mineral aggregates, representing a 2.9% increase in tonnage and a 2.4% increase in value over 1965.

Jan 2, 1968

By R. N. Upadhyay, M. Maleki, I. Fatt

Conventional laboratory core analysis tests on samples of two limestone reservoir rocks indicate that about 20 per cent of PV is in dead-end pores. These tests (electric logging formation factor, mercury injection capillary pressure and miscible displacement) were carried out on 1/4-in. diameter test plugs. Test results show a clear dilference between these samples and sandstone or homogeneous limestone reservoir rock. Although the amount of dead-end pore space can be only roughly estimated, the presence of such pore space seems clearly indicated. Pressure transient studies also show presence of deadend PV. Although they do not give quantitative results, pressure transient data yield a reasonable estimate of the size of the neck connecting dead-end pores to the main flow channels. INTRODUCTION Equations conventionally used to describe reservoir flow behavior contain the implicit assumption that all connected pore spaces contributed to both porosity and permeability. Several authors3-7 have pointed out the changes in pressure transient behavior and in electric log interpretation that may result if this assumption is incorrect and, instead, dead-end or cul-de-sac pores are present. There is a need for laboratory tests that can detect presence of dead-end pores in core samples. With such information on hand the petroleum engineer can make more rational use of the mathematical tools now available for analysis of reservoir flow behavior. This paper describes laboratory studies designed to detect and, if possible, give a quantitative measure of dead-end PV in laboratory-size core plugs. Three reservoir rocks were used, two of which were limestones suspected of having deadend pore spaces and a well-known sandstone, used as a comparison standard, in which there is believed to be little or no dead-end pore space. All the studies were designed to measure the natural dead-end PV; i.e., the pore space which is dead-ended because of rock structure. During multiphase flow in a rock without dead-end pores, some parts of one of the phases can become surrounded by the other, thereby giving (for certain flow behavior) an effective dead-end pV8,9. Such behavior will not be described here.

Jan 1, 1967

By R. W. Raymond

The various modifications of the art of photography have become within the last few years the indispensable allies of every art and science. But, before the introduction of the process which is the subject of this paper, there was, so far as I am aware, no satisfactory means by which certain photographic negatives could be made to yield, without the intervention of the skilled draughtsman, electrotypes suitable for surface-printing. I refer to negatives taken from originals, such as natural objects, or or lithographs, in which the lights and shadows are not represented exclusively by lines and dots, such as can be photo-engraved. The greater usefulness to engineers and manufacturers of electrotypes as compared with lithographs is evident. The electrotypes can be kept indefinitely and used in the production of many thousand copies. They can be duplicated at trifling cost. They can be placed for printing together with the " forms " of type, or included in these, upon an ordinary press. Finally, they are cheap, when made mechanically from a suitable original. Various methods have been adopted for the preparation of such a secondary original (as it might be called) in cases where the first original is unsuitable for photo-engraving. Thus, for instance, portraits have been produced in electrotype from ordinary photographs as follows: A large negative is made of the original (say a carle de visite of a person deceased), and a proof taken, but not " fixed." Over this proof a skilled artist draws the portrait with a pen, producing a picture which resembles a line-engraving. The photographic proof, which has served merely to guide the artist, is now obliterated, and the pen-and-ink drawing is photo-engraved. Electrotypes thus produced often retain the likeness in a wonderful degree, and give spirited and satisfactory pictures. 1 may instance, as examples, which many will recollect, the portraits of our deceased members,

Jan 1, 1887

By R. C. Gifkins, K. U. Snowden

The value of the index n in power ktivs for the stress sensitivity of minimum creep rale at lead is derived front results drawn from lite literature and from previously unpublished nork on commercial (99.99 pel) and high-purity (99.999 pel) lead polycryslalline and hi crystal specimens. In tests al 0.5Tm (22 to 50&apos;C) for slvesses below 250 psi, n fulls to mily for poly-cr,yslullirle specimens, single crystals, and bicrystals, and toy grain boundary sliding in bicrystals. Between 250 and 500 psi there is a tyansilion range and, for the polycrystalline specimens al least, u high-stress regime for 500 to 1500 psi where n is 5 or 6. These results are such that none of the suggested stress taws can he used to extrapolate to very loir stresses. Meclianisms for deformation in Ike grains and toy grain boundary sliding in the low-strcss regime are outlined. In particular, the mechanism for grain boundary sliding involves sliding controlled by diffusion from tensile to compressire Ledges. predictions based on this model give promising numerical agree-nicul with experiment. II is suggested that the mechanism for grain boundary sliding may he important in other circumstances, e.g., in creep of ceramic materials or superplaslicity, because it can operate with lille or no dislocation aclirity. WhEN the stress dependence of secondary creep rate is represented by a power law the values taken by the stress exponent n are found to vary between 1 and 7, see, c.g., Garofalo.&apos; In Eq. 1 11 u is the applied stress and A a constant. The case for accepting values of v = 1 rests principally upon tests at high temperatures (>0.9Tm) and there have only been isolated tests at lower temperatures (rather than plots of creep rate against stress) for which the creep rates are such that some form of Nabarro-Herring creep with n = 1 is applicable. Hanson5 and Greenwood and cole6 plotted creep rate against stress for tests made in the vicinity of 0.5Tw, and found a "creep yield", so that below a certain low stress the creep rate was linearly related to stress: these observations appear to have been subsequently ignored. Various models have been proposed which agree with a large body of experimental results in which n equals -5 at high stresses (e.g., weertman7 and McLean8). Various alternatives to Eq. [1] have been proposed principally as a means of unifying creep data, but sometimes, it seems, in order to obviate the necessity for assuming a series of regimes of deformation associated with the various values of n; further refer- ence to these will be made in the section on stress laws. This paper calls attention to extensive results which show n = 1 for the creep of lead at room temperature (0.5 T,). RESULTS Fig. 1 is a composite diagram based on figures in the literature6,9,10 with additional results obtained by the present authors and their colleagues11,12 in the course of a number of investigations not directly concerned with stress sensitivity. In Fig. 1 In creep rate is plotted against In stress. The curves show results for two kinds of material. Lead I is of commercial purity (99.99 pct Pb) and lead IT a specially refined material, hydrogen-purified to remove oxygen; it contains 99.999 pct Pb. Curve A is for lead I in polycrystalline form (grain diameter 0.02 to 0.05 cm) at room temperature (22&apos; to 26°C). Curve B1 is for lead I, polycrystalline, tested at 50C. Curve B2 is for lead 11, polycrystalline (grain diameter 0.02 cm), tested at room temperature (22 O- Curves C to F relate to tests made of bicrystals of lead 11: all of the same nominal orientation ("Y" in Ref. 12). Curves C and V are for creep within the component crystals of the bi crystals at 22°C (AB and CD in Fig. 2). Curve E is for creep measured in a gage straddling the boundary, approximately 0.15 mm either side (BC in Fig. 2). Curve F shows rates of grain boundary sliding (as distinct from strain rates in the other curves), obtained by averaging the offsets of six marker lines on the bi-crystal boundaries. The principal feature of the results is that the stress sensitivity falls into two distinct regimes, according to whether the stress is below approximately 250 or above 500 psi (there is a transitional range between 250 and 500 psi). The new result is that below -250 psi two of the curves (A and BI) give a value of n 1, and the other curves also drop below n - 2 to -1.5 but do not extend to low enough stresses to show clear evidence of n 1. At very high stresses the curves tend to give values of n - 6, as previously determined in other investigations. Curve R2 for the high-purity lead in polycrystalline form at room tenlperature almost merges with B, and thus gives new significance to the values for stresses of 150 and 200 psi; previously&apos;3 these points had seemed to fall away from the curve of slope -3, but they now can be seen as almost completing a transition to n = 1. It should be noted that there was originally considerable apparent scatter in the results for the high-purity lead. However, this was found to be associated with annealing conditions or variations in residual content of oxygen and curve B2 was constructed using the highest rate (i .e., the rate for the purest lead) determined for each stress during the course of various investigations over the years: altogether, some forty tests were used in constructing curve R2.

Jan 1, 1968

By H. L. Luo, P. Duwez, C. C. Chao

BY rapidly cooling alloys from the liquid state, it is possible to obtain solid solutions beyond the equilibrium concentrations, provided that the components are miscible in the liquid state. Typical such cases include CU-Ag,1 Pt-Ag,2 CU-Rh,3 nickel-base alloys with silicon, germanium, and tin,4 and cobalt-base alloys with silicon, germanium, tin, aluminum, and gallium.5 In the present note it is shown that terminal solid solutions can be appreciably extended in A1-Mg alloys. The alloys whose compositions are given in Table I were prepared by induction melting in tantalum crucibles under an argon atmosphere. Both aluminum and magnesium were 99.99 pct pure. Weight losses after melting were less than 0.2 pct for the aluminum-rich alloys and less than 0.4 pct for the magnesium-rich alloys. From these weight losses it was estimated that the compositions of the ingots after melting were accurate within 0.3 at. pct for aluminum-rich alloys and within 0.5 at. pct for magnesium-rich alloys. As indicated in Table I, the compound AuCd10 in which there is an ionic contribution to the bonding. The authors thank Dr. J. H. Westbrook of the Research Laboratory, General Electric Co., for arranging the supply of materials and for his interest. This investigation was supported by the U.S. Atomic Energy Commission under Contract AT(30-1)-1002, Scope I. some of the alloys were also chemically analyzed and the results confirmed the limits of uncertainty based on weight losses. Rapid quenching from the liquid state was achieved by techniques previously described.8,7 The principle of these techniques consists of propelling a small globule of liquid alloy (about 20 mg) onto a copper substrate. The thin foils easily detached from the copper substrate were analyzed by X-ray diffraction using a Debye-Scherrer camera 114.6 mm in diameter and either nickel-filtered copper Ka or iron-filtered cobalt Ka radiation. Since the back-reflection doublets were resolved, the wavelengths used in the computatioas were CuKal = 1.54050A and CoKa1= 1.78892A. Lattice parameters were obtained by extrapolation of the Nelson-Riley function, and the tables compiled

Jan 1, 1964

By Daryl R. Tweeton, Jerry R. Riding, Grant Buma, Frank J. Rosswog

In situ solution mining of uranium has environmental advantages over conventional mining. The leaching of uranium, however, alters the ground-water quality in the aquifer where the mining occurs. Currently, regulations require that the ground water be restored to approximately its original condition. This paper, a summary of a study funded by the Bureau of Mines, reviews the state of the art in restoring ground-water quality after in situ uranium leaching. Current restoration practices discussed include disposal of liquid wastes in deep disposal wells and evaporation ponds, producing from all wells during restoration, and recirculating water purified in surface plants. Methods for predicting the effectiveness and cost of current techniques are presented. Possible alternative techniques are also described. Two restoration operations are discussed.

Jan 1, 1979

By R. W. Smith, K. H. Lee

Bond type simulated closed-circuit grindability tests and batch grindability tests were run on six pure minerals plus a limestone and a taconite ore. The simulated closed-circuit tests were made at five different meshes of grind. The minerals tested varied widely in hardness and breakage pattern. For all simulated closed-circuit tests both Bond and Holmes work indices were calculated and compared. The Bond grindability testlm6 has been widely and quite successfully used for predictions of such items as ball mill power requirements and as an aid in plant comminution equipment selection. The test is interesting in that although run as a series of batch tests it is over-all a simulated closed-circuit test with a circulating load of 250%. The simulated closed-circuit feature is probably the primary reason for the notable success of the test. Perhaps the major criticism that can be brought against the test is that it is time consuming, since it normally takes a trained technician about an eight-hour shift to perform it.4 For many purposes this is an acceptable time requirement. However, if a grindability test is to be used for mill control purposes it should be performed in as short a time interval as possible, preferably under an hour. Sometimes in industry strictly batch tumbling mill tests are run and an attempt is made to correlate such batch tests with plant mill operation. Then an attempt is made to adjust operating tumbling mills based on data from the tests. The tests, however, frequently do not correlate well with operating data. The purpose of the present work was to explore some of the similarities and differences between a simulated closed-circui.t grindability test and a batch type test. Six different minerals plus a limestone and a taconite ore were tested in the experimentation. These materials varied widely in hardness, breakage characteristics, etc. Standard dry Bond grindability tests were mn on all materials at 48, 65, 100, 150 and 200 meshes of grind. Feed material was prepared by stage cmshing to -6 mesh. Initial feed volume was 700 cc. Care was taken to maintain the standard constant weight (about 20125 gm) and number of balls (283) during all the tests. Rotational speed was 70 rpm. Table I lists the materials studied along with pertinent data regarding the materials and Bond grindabilities obtained. In addition, dry batch tests were performed on all materials. These tests were made in the same mill as was used for the Bond tests. An identical ball charge and an identical feed volume were used. After rotating the mill for a predetermined number of revolutions at the same rotational speed as for the Bond test, the material was removed and separated from the ball charge. A screen analysis was performed on this product. Knowing the original size distribution of the feed and the size distribution of the product, it was possible to calculate the grindability or grams of a particular mesh produced per revolution of the mill. After the screen analysis of the product, the various fractions were recombined and placed back in the mill for further grinding. After grinding for additional revolutions of the mill the procedure was repeated. Thus, it was possible to obtain grindabilities for each material at a number of meshes of grind and for various revolutions of the mill. Grind-abilities obtained from batch tests are shown in Table 11. COMPARISON OF BOND AND BATCH GRINDABILITIES Figs. 1A through 1D show relationships between batch and Bond grindabilities. Figs. lA, lB, 1C and 1D show respectively graphs indicating the relationships for batch tests run for 100, 300, 500 and 700 revolutions of the mill. For a particular material on each graph, points are shown for 200, 150, 100, 65, and 48 meshes of grind except for several missing coarse meshes of grind for galena which did not fall conveniently on the figures. For each material and graph the point nearest the origin is for 200 mesh, the next for 150 mesh, the next for 100 mesh, etc. Considering Fig. lA, it is interesting to note that all relationships shown are essentially straight lines. There are, however, considerable differences

Jan 1, 1969

By W. E. Hale, G. J. S. Govett

An orientation survey was conducted over a known disseminated copper deposit and a Au-Cu vein deposit and employed geological, geophysical, and geochemical methods. Geochemical techniques proved the most effective and economical means of locating and defining areas underlain by these types of mineralization. Six additional, widely separated occurrences were also investigated and mineralization was confirmed by determination of cold-extractable copper in stream sediments. The length of anomalous drainage varies from several to 16 km and depends on the type and tenor of mineralization. Despite generally marked relief and extreme physical and chemical weathering, cold-extractable copper anomalies in soils appear to reflect closely variations in the ore mineral content of immediately underlying rocks. Threshold values vary with local geological conditions and type and grade of mineralization. Significant thresholds in stream sediments are about 65 ppm and 10 ppm for cold-extractable copper in disseminated and vein copper occurrences respectively. Similar differences are encountered in soils. This necessitates the use of a scale of threshold values at progressive stages in each exploration program. Dis-seminated copper occurrences are presently the major source of mineral production m the Philippines. Much potentially productive ground remains to be investigated and applied geochemistry appears to offer the best available approach. The Institute of Applied Geology (I.A.G.), a joint project sponsored by the University of the Philippines, the Philippine Bureau of Mines and the United Nations Development Program (Special Fund) undertook during 1965-66 a number of field projects in Northern Luzon Island (Fig. 1). These field operations were of a two-fold nature and involved both orientation and exploration. During approximately six weeks, an orientation survey, involving geological mapping, geophysical surveying and geochemical prospecting, was conducted over a partly developed, disseminated copper deposit at Santo Nino (Fig. 1). This study demonstrated the economic and technical feasibility of geochemical ptospecting, relative to the other methods tested, for the location and delineation of a typical disseminated copper occurrence characteristic of those that represent the major source of metal in the Philippines.&apos; Geochemical techniques, similar to those tested at Santo Nino, were then applied in a second orientation study of a vein occurrence at Suyoc (Fig. 1). The results of these two orientation studies suggest that, in reconnaissance work in this region, stream sediment analyses, combined with the determination of pH in the same streams, can be used to indicate areas underlain by rock containing anomalous concentrations of copper, whether it occurs in the large tonnage, low grade, disseminated deposits or in the comparatively small tonnage, higher grade, gold vein occurrences. Furthermore, the orientation surveys demonstrate that soil sampling and analysis serve effectively to outline more closely the mineralized zones within the generally anomalous areas identified from the stream reconnaissance. To further test the methods selected from the two earlier trials, six additional, widely separated prospects were investigated. The geological and geochem-

Jan 1, 1970