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By D. Weinstein

The high temperature mechanical properties of stainless steels after fast neutron irradiation are discussed in the light of effects caused by lattice dattmage and effects caused by helium generated from n,a transmutations. Embrittlement at high temperatures is due to helium accumulation at grain boundaries and to cavity formation and proPagation along grain boundaries. Following from the embrittlement mechanism, it is suggested that when deformation occurs by mechanisms associated with super plasticity, helium ac-curnulation at boundaries should be attenuated and cavities, if formed, should be nonpropagating. As the mean free Path between interphase boundaries of a two-phase Fe-Cr-Ni alloy was decreased, the degree of superplastic deforrnation at 870°C increased, as vneaszired by total elongation and by the expottent m = a log 'a/a log 'i. This alloy and type 304 stainless steel were cyclotron irradiated in an a-particle beam to a helium concentration of -1 x 10 atom He per atom. The stainless steel specimen was embrittled, but the ductility of irradiated two-phase Fe-Cr-Ni alloys correlated with the values of. m during 'defor-malion. The .finest grained, helium-injected specimens that deforrned with highest m values exhibited the largest elongations to ,fracture. These results could be correlated with metallographic observations of cavity behavior: the propensity for intergranular propagation was lessened as the m value increased. It is concluded that superplastic deformation is ef-fectizle in attenuating helium embrittlement at elevated temperatures. One of the principal problems associated with development of fast breeder reactors is application of alloys such that suitable fuel cladding results. Stainless steels and other Fe-Cr-Ni alloys, because of highly acceptable nuclear characteristics, represent the primary materials for this component, and an exhaustive research and development effort is being conducted. The main deficiency of these materials has been a severe loss of ductility at high temperatures after fast neutron irradiation. An extensive body of mechanical property data and microstructural observations has provided an adequate phenomenological description of embrittlement; in conjunction with transmission electron microscopy studies, a reasonably acceptable embrittlement mechanism has been obtained. Following from this mechanism, it is suggested in the present work that ductility would be enhanced if deformation could occur by mechanisms associated with the phenomenon of superplasticity. Experiments to test this hypothesis have been conducted, and the results are presented and discussed in this paper. IRRADIATION EMBRITTLEMENT AT HIGH TEMPERATURE Austenitic stainless steels have been irradiated to accumulated fast neutron fluences of 1020 to 1022 nvt at temperatures between 60" and 600°C. Specimens that have been exposed to these conditions and subsequently tensile tested at temperatures between 600" and about 900°C exhibit approximately 5 pct total elongation to fracture.'-3 For unirradiated specimens receiving a nearly identical thermal exposure, total elongation at these test temperatures is about 45 pct. Examination of irradiated specimens has shown that fracture propagation is entirely intergranular. These phenomenological aspects of irradiation embrittle-ment at elevated temperatures are well known and are not generally disputed. Although the explanation of this phenomenon has been controversial, a mechanism for ernbrittlement has emerged that accounts reasonably well for the observed mechanical behavior. The controversy resulted primarily from an indeterminate role of neutron-in-duced lattice damage, if any, and a presumed, but experimentally unverified, contribution to embrittle-ment from helium generated by n,a transmutations. Recently, Holmes and coworkers4 have conducted experiments that separate these effects, and the results are instructive in formulation of the ernbrittlement mechanism. Holmes el al.4 irradiated type 304 stainless steel in EBR-I1 to a fluence of 1.4 x 1022 nvt (E > 0.18 mev); the irradiation temperature was 538" * 48°C or, in terms of absolute melting point, 0.49 * 0.03 T,. After irradiation, tensile tests were conducted at temperatures of 21" to 870.C, the specimens first being annealed for 30 min at each test temperature. In addition, thin sections of irradiated specimens were annealed for 1 hr at identical temperatures, electro and examined by transmission electron microscopy. Thus, for a given temperature, it was possible to correlate mechanical properties with the defect structure. At room temperature, the yield stress of irradiated specimens was a factor of 2.5 higher than unirradi-ated specimens exposed to an equivalent thermal history. Electron microscopic examination of the irradiated specimen revealed a high density of lattice damage in the form of Frank sessile dislocation loops and polyhedral voids. Holmes et al.4 concluded that the presence of this defect substructure caused the increase in yield stress and that after irradiation in a fast neutron flux at 0.49 Tm, substantial lattice dam-age persists. Annealing at progressively higher tem-

Jan 1, 1970

By Carl O. Theime

Industrial specialization has rapidly created a demand for new and better alloys. A more thorough understanding of the requirements of specific industries and the discovery of processes by which it has been made possible to utilize certain metallic elements in larger quantities, together with greater purity in most virgin metals, has resulted in a great increase in the number and variety of alloys. This increase in the number of elements entering into non-ferrous alloy manufacture has increased the contamination in secondary metals, as received by the smelter. In order to successfully refine scrap of a much more complex nature it has been necessary for the smelter to install new equipment and to constantly search for new methods of refining as well as to improve the methods already in use. In some instances it is largely responsible for specialization in the secondary metal industry. It is usually necessary to remove the contaminating impurities in scrap or eliminate to a degree not objectionable, no matter how introduced. In order to know what metals or elements are of an objectionable nature, the smelter must make a study of the effect of single elements and combinations of elements on many of the physical and mechanical properties, such as strength, ductility, color, hardness, casting soundness, etc. The smelter of secondary mctals must be able to utilize scrap materials of all kinds, for, sooner or later, most fabricated metal parts and the waste products formed during the process of manufacture find their way to the smelter. In addition, the smelter, in contracting for salvaged material from the producer, gets some undesirable and unusual materials. The value of secondary metals and the importance of their recovery has increased in recent years and it is no longer sufficient to recover the base metal only, such as copper from copper-bearing material, but it is essential that other elements present be recovered and converted into useful form. This paper will deal not with the smelting and refining or separation of impurities from secondary metals but an attempt will be made to show the increased value of metal scrap when properly segregated and in a less contanlinated condition. There are five principal reasons for contamination in secondary metals: New and unusual alloys, productive methods,

JULY was a month of great turmoil, both economic and political, in many parts of the world. Instead of conditions improving, they seem to have been getting worse. In Ireland, civil war is still in progress. Germany was in the throes of a political upheaval. The meaning of the assassination of Rathenau became clear. It evinced the development of a class struggle between the bourgeois and socialistic parties which may rock the country to its foundation and will increase the difficulties of arranging things with the French and solving the reparations problem. In Poland, a similar contest is developing. Austria is already so completely contaminated by the socialist element that it is unable to get outside assistance and is thus falling into a state of despair but little short of what prevails in Russia. The conference at the Hague came to an abortive end for the reason that it was impossible to discuss affairs with the Russians in any reasonable way. The Germans declared their inability to meet the reparation payment that fell clue on July 15 and the Commissioners for the Allies granted them an abate-ment of a portion thereof and are listening attentively to the supplication of the Germans for a moratorium of one or two years. In the United States, July was a month of widespread labor troubles, accompanied by a great deal of disorder and violence, which led to detachments of the National Guard being called out in several states. The railway shopmen, about 400,000 in number, struck on July 1. The road maintenance men decided not to strike, but many thousands of them quit work without the sanc-tion of their union. There were more strikes in the textile industry in New England and in similar industries all over the country. Early in July, it was estimated that about 1,250,000 men were out on strike. The coal strike continued. Early in the month the President summoned operators and miners to Washing-ton and submitted a plan for the compromising of disputes. After a week's consideration the miners re-fused flatly to agree to anything. The majority of the operators consented to accept the proposed arbitration, but a minority refused. Following this abortive at-tempt the President dismissed the conference with the injunction "to return to your mine properties and resume operation." Production has not increased.

Jan 8, 1922

By R. T. DeHoff, F. N. Rhines

The problem of determining the number of particles of a phase distributed randomly in unit volume c an opaque matrix from measurements made on random plane sections is closely investigated. A formalized derivation for the general case is presented. Applications of this formal result are made to specific types of aggregates dispersed in a matrix; circles, particles with flat circular ends, cylinders, and constant shape aggregates of ellipsoids of revolution. Quantitative measurements of the average geometric properties of these aggregates are developed. In 1953 R L. ullman' developed a technique for determining, from measurements made on random plane sections, the number per unit volume, Nv, of particles imbedded in an opaque matrix. Using meas urements previously developed for volume fraction, vV,' and surface area per unit volume, .SV,= he was able to determine average volume, average surface area, and average dimensions of particles, independent of size distribution, for spheres and circular disks,' as well as for uniformly sized cylinders of any axial ratio.4 The technique is mathematically rigorous for the cases studied. Recent studies of this problem have yielded rigorous solutions for the general case of cylinders, permitting evaluation of NV independent of size distribution and with all axial ratios intermixed. Generalization to shapes having flat, circular ends has been deduced. A solution has also been obtained for the ellipsoid of revolution, independent of size distribution, but requiring a constant axial ratio in the generating ellipses. In the following derivations, as in Fullman's work, it is assumed that the problem is purely a combination of geometry and probability theory,that is,eithe the particles to be measured are imbedded randomly in the matrix, or a sufficient number of random plane sections are taken to make the sample representative. A relationship exists between the number of par- ticles of a given size and shape that may be situated in unit volume (Ny) and the number of intersections a random plane can be expected to make with these particles (Na). It is the purpose of the following section to derive this relationship. The probability of Intersecting Convex Bodies. Consider a convex, closed surface, that is, one for which no two surface normals point in the same direction, situated at some arbitrary position and orientation in a cube of material that is one unit long at each edge. It is not necessary to assume that this surface is symmetrical. Let planes be constructed in the cube parallel to the top face and at random distances from it. Those planes which lie between the two planes which are just tangent to the top and bottom of the surface will intersect it. The probability that a plane will intersect the body may be defined as the limit of the fraction of planes that lie between the two tangent planes as the total number of planes constructed becomes infinite. This fraction, in the limit, is equal to the distance between the two tangent planes, DV, divided by the total length over which planes are constructed, which has been taken as unity. If the body is now rotated to a new orientation, applying the same argument, the probability of intersection is again numerically equal to the distance between tangent planes. Let DV ($, 0) be defined as the distance between tangent planes of a convex body as a function of orientation, Fig. 1. The probability, Pr, of intersecting the body with a randomly oriented and randomly positioned plane, is then equal to the average value of DV (0, $) over all possible orientations. It may be easily shown that for a system of spherical coordinates the probability of finding an orientation between Q and Q + de, $ and $ + d$ is (1/4n) sin $ dB d$, so that This relationship may be applied to each body in an aggregate of convex bodies. In particular, if the bodies in an aggregate are classified according to size and shape, and the ithsuch class is considered, Eq. 111 may be applied to this entire class, the probability of intersecting any body in this class being

Jan 1, 1962

By Thomas Haight Leggett

I.—The Deep-Level Shafts. The gold-deposits of the Witwatersrand (Anglice, " White Waters' Range ") are, as is well-known, more or less parallel and tilted sedimentary beds of quartz-pebble conglomerate impregnated with gold. These beds, however, are locally called "reefs"—a term equivalent in signification to the American "ledge"—and, like the latter, usually applied to lodes, though covering in practical usage all deposits of tabular form. The first developments of the reefs of the Rand were naturally made along their outcrops. Since the mining law of the Transvaal does not confer upon locators the "extralateral right," the property of each locator upon the outcrop or apex ends with the vertical planes drawn through the boundaries of the claim. Consequently those portions of the reefs which lie "on the dip," beyond these boundaries, are separately acquired by locating new surface-claims, and are usually to be mined only by means of vertical shafts, reaching the reefs at considerable depths. The term "deep-level properties " is given to such claims on the dip, and the " deep-level shafts " are the vertical shafts sunk in the hanging-wall of the Witwatersrand reefs, in contradistinction to the incline-shafts almost universally employed on the outcrop-properties. Number and Distribution.—The accompanying diagram, Plate I., shows the number and depth of these deeplevel shafts, completed or under process of sinking, up to January 1, 1900. A number of shafts already located upon new deep-level properties, but upon which no work has yet been done, are not included in this diagram.* Vertical shafts sunk upon outcrop-

Jan 1, 1901

By Alden B. Greninger

That metallographic structures analogous to the martensite of steel may be found in certain copper-aluminum and copper-tin alloys has been known for many years; similar structures recently were found in certain copper-zinc a1loys.l In all three of these alloy systems the martensite structures result from transformation of the metastable fi phase when the speed of cooling from the B range is sufficiently high to suppress decomposition into equilibrium phases. In the normal decomposition of solid solutions into equilibrium phases, diffusion is needed to bring about the necessary changes in concentration, and the rate of reaction falls almost to zero at temperatures slightly above room temperature. The rates of reaction for martensite processes, however, are not dependent upon temperature; the transformation does not require rendjustments of concentration. For example, the martensite transformation in 60:40 (B) copper-zinc does not begin until the temperature has dropped to about minus 30" C., and then continues down to minus 130" C. and probably even at lower temperatures.' Furthermore, martensite processes apparently proceed only while the tempcrature is falling, within the proper range, and cease completely while the temperature is held constant ;$ and they cannot be suppressed by extremely rapid cooling although the rate of cooling for some alloys may be increased to over 10,000 times the critical cooling velocity. Isaitschew, Kaminsky and Kurdjumow2 account for these observed behaviors of rnartensite processes by postulating that the mechanism 6I... consists in a regular rearrangement of the lattice in such a way

Jan 1, 1939

By Alden B. Greninger

That metallographic structures analogous to the martensite of steel may be found in certain copper-aluminum and copper-tin alloys has been known for many years; similar structures recently were found in certain copper-zinc a1loys.l In all three of these alloy systems the martensite structures result from transformation of the metastable fi phase when the speed of cooling from the B range is sufficiently high to suppress decomposition into equilibrium phases. In the normal decomposition of solid solutions into equilibrium phases, diffusion is needed to bring about the necessary changes in concentration, and the rate of reaction falls almost to zero at temperatures slightly above room temperature. The rates of reaction for martensite processes, however, are not dependent upon temperature; the transformation does not require rendjustments of concentration. For example, the martensite transformation in 60:40 (B) copper-zinc does not begin until the temperature has dropped to about minus 30" C., and then continues down to minus 130" C. and probably even at lower temperatures.' Furthermore, martensite processes apparently proceed only while the tempcrature is falling, within the proper range, and cease completely while the temperature is held constant ;$ and they cannot be suppressed by extremely rapid cooling although the rate of cooling for some alloys may be increased to over 10,000 times the critical cooling velocity. Isaitschew, Kaminsky and Kurdjumow2 account for these observed behaviors of rnartensite processes by postulating that the mechanism 6I... consists in a regular rearrangement of the lattice in such a way

Jan 1, 1939

By Jon E. Fatzinger

The design of a centrifugal slurry pump is approached as a compromise between efficiency and wear life of the wetted parts. This compromise is effected by the choice of proper materials of construction and geometry. However even the most optimally designed pump will fail if due consideration is not given to its installation and operation. System head curves and hydraulic profiles are discussed as useful tools to be used in the operational analysis of a slurry system.

Jan 1, 1978

By J. A. Ede

THE object of the writer is to call attention to a rather unique aggregation of economic products distributed over a line of succeeding formations about 3 mi. long, to be seen within a few miles of La Salle, Ill. Fig. 1 is an ideal section of the stratification exposed and exploited along a distance of 3 1/5 mi. in a southwesterly direction from the quarry of the Utica Hydraulic Cement Co. located near the historic site of Kaskaskia village to the Oglesby, shaft at Oglesby. No attempt has been made to cover the whole field, special mention only being made (with the exception of two places) of the operations found along the course or parallel to the direction assumed in the ideal section. I have used Fig. 2, after J. H. Bent and De Witt Kelly, to locate the relation of the La Salle anticline to the coal mines of this district and to show the operation of No. 1 and 3 mines of the Illinois Zinc Co.

Jan 9, 1919

By T. N. McVay, E. E. Creitz

INTRODUCTION Object RATHER large amounts of titanium minerals and some zircon and monazite are being recovered from dune sands about 10 miles west of Jacksonville Beach, Fla. The Mining Branch of the Bureau of Mines, Southern Experiment Station, has been interested in developing additional large deposits of similar sands in other areas of Florida. The results of a field study have been published1 concerning the sands occurring on Trail Ridge which runs north and south about 30 miles southwest of Jacksonville. This investigation was undertaken in order to identify the opaque titanium minerals occurring in Trail Ridge and because of the economic importance of Florida titanium minerals. Nature of the Problem The minerals present in the heavy fractions (sp gr > 2.94) of the sands are principally opaque minerals; staurolite, zircon, sillimanite, tourmaline, kyanite, rutile, a small amount of corundum, traces of the zinc spinel gahnite and garnet. Epidote, monazite, hornblende and titanite are present in other dune sands but these minerals were not noted in the samples collected on Trail Ridge. All of the minerals except those which are opaque can be readily identified by the usual petrographic methods. However, opaque minerals cannot be examined satisfactorily by transmitted light. Polished sections of the opaque-mineral grains were examined but these sections did not furnish useful information. Consequently, it was necessary to use means other than the usual petrographic methods to identify them. Previous Investigations of Heavy Minerals in Florida Sands Martens2 has described the heavy minerals in the Florida beach sands and has classified the opaque minerals as ilmenite with minor amounts of leucoxene. Miller3 studied a number of sands collected by Ross and Mertie in Florida. He states that the material from the Florida beach and dune sands that commonly has been called ilmenite has essentially the chemical composition of the material that has been called arizonite.4 The X ray diffraction patterns of several samples indicated that the supposed ilmenite is essentially amorphous, with only weak lines corresponding to ilmenite, and hence the material is unlike the type of arizonite from Arizona. Opaque Titanium Minerals Rutile is essentially titanium dioxide. However, as pointed out by Dana,5 important amounts of Fee and Fe3 as well as Cb and Ta are reported in some analyses.

Jan 1, 1947

By Thomas Egleston

The uncertainty of finding the exact equivalents fortechnical expressions in different languages has led me to think that a glossary of furnace-terms would be useful to members of the profession. I was led, some years ago, to prepare a small one, which has been found so very useful, that I have arranged one for presentation to the Institute, for four different 'types of furnaces, in the hope that it may prove of use to those who are in the habit of consulting foreign technical journals, I was further induced to make the attempt in the hope that it might tend to make the terminology less complicated than it now is, and also to make it more uniform over larger districts. The idea of referring to a drawing which expresses exactly what is meant, resulted from the necessity of presenting such subjects to students, and will, it is hoped, prove much more useful than the mere dictionary arrangement in alphabetical order. The drawing of the blast-furnace was prepared for me by Mr. J. P. Witherow, of Pitsburgh ; the drawing of the open-hearth furnace by Mr. S. T. Wellman, of Cleveland, and the reverberatory furnace by Mr. John Fritz, of Bethlehem. The bloomary-furnace is taken from my own paper* on Bloomaries, but, in order to have a complete furnace, I have introduced into the drawing of those used at Saranac the guard-plate used at Ironville. The interest which has been taken in the preparation of this paper by those gentlemen who have contributed the drawings, has been supplemented by gentlemen in Europe who have taken the trouble to read the proof. In France it has been read by Mr. Lodin, of the School of Mines, and by Mr. Chaper, of Paris, and in Germany by Dr. Wedding, of Berlin, and Mr. Luhrman, of Osnabruck. The preparation of the paper has been much more difficult than was anticipated, and its value has been very much enhanced by Dr. Raymond's kind assistance and cooperation; and to him, as well as to all the other gentlemen, Iam very much indebted. It was at first proposed to add to the paper the names of all the tools used in these various furnaces. It was found, however, that this would make such

Jan 1, 1888

By S. W. Miller

Most of the steel welding done at the present time is in material containing not over 0.3 per cent. carbon, and the tests here described were in similar material. These tests are not as yet completed but it is hoped that more results and more reasons for the conclusions may be presented at the meeting in February. From the time the author found the peculiar structure in electric welds referred to in a previous paper,' that is, needles or plates in the grains and similar material, in larger spots, at the grain boundaries, he has felt that these plates which may be iron nitride and probably contain some carbon, were at least partly responsible for the brittleness of electric welds. He has found but few traces of similar lines in oxyacetylene welds until the last 2 mo., he has since found large numbers under certain conditions. In the top of these welds, they are quite numerous. In the body of heavy oxyacetylene welds, they appear at times, but not nearly to the extent that they do in electric welds; the author has never seen them in the body of welds in material less than % in. (19 mm.) thick. They are shown in Fig. 82. The reason they were not noticed before is undoubtedly due to the fact that in making tests of welded pieces the weld was always ground off level with the plate, and as this structure only appears in the top 1/16 in (1-5 mm.) of the weld, they were removed by the grinding or machining; also, welds 3/4 in. thick had not been examined. It did not appear, in making bending tests, that this structure had much influence on the strength of oxyacetylene welds; while electric welds are noticeably brittle. Further, oxyacetylene welds made with certain special materials were exceedingly brittle even after the tops of the welds were removed; this was true in cases where there was no sign of the plates whatever and where the welds were remarkably free from oxide and the other usual defects. It appeared, therefore, that this brittleness did not depend on any variable that had been noticed so far, and it was decided to find where the rupture occurred in various kinds of welds made

Jan 1, 1920

By Robert L. Thoms, Joseph D. Martinez

The development of Gulf Coast salt domes thus far, although enormously successful and productive, has proceeded in an unscheduled fashion governed by events rather than by a comprehensive plan. Motivation for the sequential progress of exploitation has included mineral discoveries, inventions, technological improvements, new needs, and a dynamic economy. Although it is too late to implement a plan for the entire cycle of exploitation of this resource, it would seem advisable to introduce now a system concept for further development. Viewed from this perspective, general determinative parameters should include economic, environmental, logistical, technical, and resource considerations, and more fundamentally, basic societal goals. Experience gained from planning in the Gulf Coast should provide guidelines for use elsewhere in the world.

Jan 1, 1981

By Rossiter W. Raymond

The substance known as carbonite, or natural coke, has been several times the subject of comment before the Institute. The most important contribution hitherto made to the discussion is that of Dr. Henry Wurtz, of Hoboken,* who states, upon the strength of a chemical analysis, that carbonite is not a coke, but contains 14.08 per cent. of volatile combustible matter. In 1882 a mine was opened upon a carbonite seam, near Midlothian, Chesterfield County, Va., by Messrs. Jewett & Brother, of that place. The seam, which dips westerly at an angle of about 30 degrees, was struck at the depth of 137 feet with a vertical shaft, and followed on the dip 325 feet, at which depth gangways were opened north and sooth. For these statements (having made no personal examination of the locality), I am indebted to Mr. Albert Blair, of Richmond, and for the following section, to Mr. John Bladon, engineer at the mine. The section was taken in the face of the gangway, February 17th, 1883. It shows an aggregate thickness of 15 feet of "coke," of which about 5 feet were extracted by the system employed last winter. It is reported that under the "coke" seam there is a thick seam of highly bituminous coal, which has been extensively worked on a neighboring property, a little south of the Jewett colliery, the coal being sold for gas-waking. The carbonite is used for domestic purposes, and is said to burn

Jan 1, 1883

By P. L. Allsman

Butte mining district contains extensive manganese vein deposits forming a peripheral zone. Oxidation in the veins studied usually extends to a depth of about 75 ft. Secondary minerals formed by oxidation were found to be ramsdellite—always accompanied by intermixed pyrolusite—and cryptomelane. Enrichment of the gossan is accomplished by reduction of weight upon oxidation; theoretical enrichment is 32.2 pct. Additional enrichment is caused by leaching of soluble minerals, particularly calcium and magnesium carbonates. BUTTE mining district contains extensive manganese vein deposits in the outer zone, surrounding the copper and zinc deposits and corresponding to the well known silver zone. This article describes the mineralogy of the manganese veins, the oxidation and enrichment processes, and the use of this information in prospecting. Information was derived from a study of the Emma, Star West, Tzarena, and Norwich mines, selected as representative of the district. Vein exposures at these mines were mapped, studied, and sampled on the outcrops and throughout the oxidized zone. Specimens were cut and polished for minera-graphic examination, identification, and textural studies. Knowledge of the manganese oxide minerals is scanty, previous information having been rendered obsolete by publication of the first correctly identified list of manganese oxide minerals by Fleischer and Richmond in 1943. Positive identification of the manganese oxides is possible only by X-ray analysis. Identifications for this study were made by the author with a Phillip's Diffractometer at the Montana School of Mines and confirmed by Lester Zeihen of The Anaconda Co., using a Norelco X-ray camera. It was necessiary to re-evaluate some X-ray data, as published patterns of several manganese oxides proved to be of mixtures, mostly showing pyrolusite as a contaminant. Perhaps the most useful information on oxidation and enrichment of manganese is presented in recent books by Goldschmidt1 and Rankama and Sahama.2 While their hypotheses are not conclusively proved, all laboratory and field evidence has served to substantiate them. This information was very useful in this study. Mineralogy: The primary minerals of the manganese veins are chiefly rhodochrosite and quartz. Rhodonite is abundant in the northern part of the district and in places has been found to comprise over a third of the vein matter. A variable but generally small amount of sulfides may be present, principally pyrite and silver minerals. Sphalerite is progressively more abundant near the zinc zone. Rhodochrosite is believed to form complete iso-morphous series with siderite, ankerite, and calcite. Some variation into these compositions is common, and the intermediate forms are termed manganosid-erite, manganankerite, and rnanganocalcite. Much of the rhodochrosite is remarkably pure. Other manganese minerals in the district include huebner-ite, alabandite, and helvite. Ramsdellite (MnO2, orthorhnmbic) is the principal manganese oxide mineral, comprising perhaps two-thirds of the total oxides. It is dull to iron black, and generally massive or platy in structure. A prominent platy cleavage is the only distinguishing megascopic characteristic. Pyrolusite (MnO2, tetragonal) is next most abundant to ramsdellite, with which it is usually intimately mixed. The luster is often brighter or more metallic than in ramsdellite, and needle-like crystals are diagnostic. Pyrolusite is common in small cavities formed by oxidation of pyrite grains. It is relatively abundant in zones of high limonite content. Cryptomelane (KMnO16 tetragonal ?) is rare in the outcrop, but becomes more abundant with depth. At depths of several hundred feet it is the principal oxide. Although its appearance varies, a blue-black flinty luster and blocky to conchoidal fracture are most common. A potassium flame test will identify this mineral. Hardness of all three oxides varies from 2 to 6. The three are quite commonly intermixed, and their textures can vary greatly. The commonest textures are massive or colloform, representative of colloidal deposition, or vuggy and boxwork textures, formed by partial leaching and oxidation in place. A box-work of either ramsdellite or chalcedony is formed after rhodochrosite rhombs and is indicative of ore shoots in this district. Some replacement of both quartz and the granitic wallrock by ramsdellite has been noted, but most of the oxide was deposited as a fissure filling by fine particles. No trace of manganite, hausmannite, braunite, or manganosite was found. No minerals of the psilome-lane group were detected besides cryptomelane. Amorphous MnO, was found at several spots. A specimen of oxide coated with yellow barite crystals was amorphous and not psilomelane (BaMn9O18. 2H2O). Voids formed by the leaching of sphalerite were coated with cryptomelane, not hetaerolite (ZnMn2O4) as might be expected. No manganese sulfate minerals were found in the gossans; however manganese alum (apjohnite ?) has been re-

Jan 1, 1957

By W. Hurst

The authors of this paper, in substituting values in a material balance equation associated with a gas reserve and a water drive, cannot find sustainment of what the gas in place should be; therefore, their conclusion is that this type of problem dealing with gas reservoirs is insoluble. They have introduced the word, "cybernetics," based on the work of Norbert Wiener, that further extends this line of reasoning, namely, to the effect that the system is a "black box", and that the gas reservoir and aquifer can take on infinite aspects 'based upon their past performance, to quote the authors. The inference is that this black box is an unknown. which permits in computer programming to subscribe as many variables as possible to observe by adjustment of one to another those combinations of conditions that fit field behavior. This may satisfy those in this discipline whose dedication is to programming, but to the others this is a comparison to the rationalization of the combinational results of the throwing of dice—a probability procedure. In reservoir engineering we are more direct. We learn from the examination of individual we'll and field data exactly what is in this black box. I now come to the impasse that has confronted these authors in their machine calculations. In this I have reproduced from their own production data (Tables 1 and 2 of their paper) pressure vs cumulative gas produced. shown as Figs. D-1 through D-5. A perusal of any of these five plots, for the corresponding fields in the Po Valley, shows the straight-line relation of pressure vs gas produced, evidencing pressure depletion. The point I make is that in their fundamental production data, there is no variance from a straight line that can support a water drive.

By Milton E. Wadsworth, W. Martin Fassell, William H. Dresher

A study of the rate of dissolution of molybdenite (MoS2) in alkaline solution was carried out under carefully controlled conditions. Effects of temperature, oxygen over-pressure, and KOH concentration were evaluated. Studies were made in the temperature range 100°C to 175°C and in the pressure range 0 to 700 psia of oxygen. Under these conditions molybdenite was found to leach according to a linear mechanism. Both oxygen over-pressure and KOH concentration were found to control the rate of leaching. The mechanism has been explained in terms of adsorption of oxygen at the molybdenite surface followed by configurational rearrangement of the adsorbed molecules. The hydroxyl ion dependency is believed to be diffusion-controlled. Laboratory batch studies have shown that molybdenite can be readily dissolved in alkaline solutions under moderate conditions of temperature and pressure. Commercial application of this process to the production of ferro-molybdenum and molybdenum chemicals is promising in view of the ease of dissolution of molybdenite and the relatively noncorrosive conditions involved in the process.

Jul 1, 1956

By E. S. Machlin, Morris Cohen

The isothermal formation of martensite in a 71 pct Fe, 29 pct Ni alloy is found to take place mainly by the nucleation of new plates rather than by the growth of existing ones, and is dependent on the temperature and time of the isothermal hold, the amount of atherrnal martensite present, the state of internal strain, and the application of tensile stress. The conclusion is reached that the isothermal nucleation is activated by thermal fluctuations superimposed on localized regions of very high strain. The reaction-path concept, involving martensite nucleation at strain embryos by athermal activation on cooling, or by thermal fluctuations on holding, reconciles the athermal and isothermal modes of transformation, and offers a unified picture of the kinetics of martensite formation. THE phenomenon of isothermal martensite formation has been the subject of considerable study lately,'-' and its reality has been thoroughly established. The existence of such isothermal transformation has been claimed to confirm the nucleation and growth hypothesis as applied to the martensitic reaction.1 " However, the isothermal formation of a martensitic phase is also compatible with the reaction-pathw escription of the transformation. The purpose of this investigation is to examine the isothermal mode of the martensitic reaction, both theoretically and experimentally, in order to test the likelihood of the above two mechanisms. Material and Methods The alloy used in this study contained about 71 pct Fe and 29 pct Ni. The complete analysis was 29.5 ± 0.2 pct Ni, 0.036 pct C, 0.02 pct N, 0.19 pct Mn, 0.09 pct Si, 0.008 pct P, and 0.006 pct S. The amount of isothermal transformation was determined by electrical resistance measurements using a Kelvin double bridge. The specimens were in the form of rods 1/16 in. diam x 4 in. long. Aus-tenitizing was performed at 1095°C for % hr either in a pre-purified nitrogen atmosphere or in an evacuated Vycor tube, followed by oil quenching to room temperature. After this treatment, the samples were completely austenitic, and the transformation studies were conducted at subatmospheric tempera- tures. Lineal analysis and X-ray determinations of retained austenite were used to calibrate the electrical resistance changes in terms of the percentage of martensite. The martensite range curve for this alloy is given in Fig. 9 of ref. 6. The M, temperature occurs at about -18°C (255°K). Reaction-Path Theory The nucleation and growth description of the martensitic transformation that occurs isothermally has already been given by Kurdjumow.','2 However, no comparable treatment exists using the reaction-path concept." Consequently this section presents the reaction-path description of the isothermal mode of the martensitic transformation. According to the latter theory, there is a reaction path (a strain) which describes the relative motion of the atoms during their transference from the austenitic to the martensitic state. The possibility exists, therefore, that the nucleation of a martensitic plate is accomplished by an embryo that comprises a state intermediate between that of austenite and martensite. This state may be attained within a finite volume by means of a homogeneous strain of the austenitic matrix. There is a free-energy barrier (F.) along the reaction path, corresponding to a critical strain in a critical volume. When activation is achieved, a spontaneous increase in strain and volume of the embryo takes place to generate the full-size martensitic plate. This mode of nucleation is to be distinguished from the more conventional mode involving embryos of the martensitic phase that merely grow in size by an interface motion. There are two ways whereby embryos in the austenitic phase can achieve the critical state of strain for isothermal nucleation: 1—through the formation of internal strains by plastic deformation or by stress; and 2—through thermal fluctuations, preferably superimposed upon existing internal strains. The activation free energy F,, must be supplied either mechanically by internal strains or thermally by energy fluctuations, or by a combination of both.

Jan 1, 1953

By R. E. Reed-Hill

Recently Levine applied the Conrad-Wiedersich17 equation where H is the activation enthalpy, v the activation volume, T* the effective shear flow stress, T the absolute temperature, and ? the strain rate, to an analysis of titanium single-crystal data. The activation energy as a function of testing temperaturs obtained from specimens oriented for single (1010) prismatic slip is shown in Fig. 12. This diagram indicates a different linear dependence of H on T in the temperature interval from 220° to 300°K than from 0° to 220°K. Levine interpreted the break in this curve as indicating a change in the thermally activated mechanism controlling the flow stress. The purpose of this communication is to point out that the data in Fig. 1 is not consistent with the concept of a flow stress controlled by a simple thermally activated mechanism between 220° and 300°K. The Conrad-Wiedersich relation assumed that the strain rate can be expressed by:

Jan 1, 1968

By R. J. Jackson, D. E. Williams, W. L. Larsen

The phase diagram of the Ta-Zr system is presented with a discussion of the methods used in its determination. The solidus contains a minimum at 1820°C near 25 wt pet Ta. A complete solid solution exists at elevated temperatures between tantalum and ß zirconium. This solid solution decomposes monotectoidally at 800°C and 12 wt pet Ta. The maximum solubility of tantalum in a zirconium is slightly less than 2 wt pet, and decreases with decreasing temperature. The solubility of zirconium in tantalum is 5 wt pet at the monotectoid temperature and about 2 wt pet at room temperature. THIS investigation was part of a program of research on refractory metal alloy systems having potential application in nuclear reactor technology. Preliminary prop-ess has been reported in the Ames Laboratory annual research reports.l Most of the previously reported work on the Ta-Zr alloy system consisted of partial phase diagram investigations and the determination of the mechanical properties of the zirconium-rich alloys. Anderson eta1.2 studied alloys containing up to 30 wt pet Ta as part of an investigation of several zirconium alloy systems. These investigators also determined some of the mechanical properties of the alloys at room temperature and 650°C. In a discussion of Anderson's work, Pfei13 suggested that the bright phase in the microstructures of the intermediate alloys is a tantalum-rich solid solution or an intermediate phase in a matrix of ß zirconium solid solution. Litton,4 Keeler,5 and Chubb6 determined the mechanical properties of zirconium-rich alloys at ambient and elevated temperatures. Van Thyne and McPherson7 reported the tensile properties

Jan 1, 1962