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By R. H. Hiltz

Three titanium alloys, known to provide a mechanically unstable p structure after quenching, were selected as material for a study of the Origin and nature of stress-induced transformation. Data from hardness and tensile tests were used to study the initiation of marten site and the effect of the transfornation and transformation products on the mechanical properties of B titanium, particularly the stress-strain relationships. With the exception that the materials investigated showed a natural aging reaction in the P condition, their behavior is analogous to that of' stress-transforming stainless steels. The transformation starts after initial yielding and is essentially complete just prior to .maximum loading. Once initiated, the martensite itself is capable of propagating the transformation. The deforn-ing materials show low strength, high ductility, and a high strain-hardening exponent. In metallic systems which undergo a diffusionless transformation on cooling, it is possible to produce a similar transformatiorl by plastic deformation under special conditions. Dewez' in delineating Ms temperatures for the titanium-rich end of most titanium binary systems:, established the point of intersection of Ms with room temperature for those particular alloys. Alloy compositions which would quench to mechanically unstable p were established from these data. The first investigation into the possibility of stress-induced transformation occurring in titanium met with little success. It was concluded that such a transformation in titanium was possible only under very special conditions. Continued effort in this direction, however, showed certain Ti-Mo binaries to be highly susceptible to this phenomenon. This fact was utilized by Liu to study the habit planes of martensite and by Machlin and wenig5 to study the effects of stress and plastic deformation on the P to a prime transformation in titanium alloys. The first investigation of the mechanical properties of these alloys was conducted by Holden and his coworkers at Battelle Memorial Institute.' The potentiality of the alloys i3s sheet-forming material was recognized, and the data reappeared in a survey of this type of titanium material.? The initial optimism was tempered by the difficulties in obtaining homogeneous 2i-Mo alloys in commercial-size ingots. The increasing need for good sheet-forming material kept investigation in this direction active, resulting in the development of a commercial alloy of this type.' This study was undertaken to obtain a clearer picture of the mechanism of stress-induced transformation in titanium. MATERIALS AND TEST PROCEDURE Three alloys were selected for this investigation: one a Ti-Mo alloy; another a Ti-Cr-Mo alloy, known to deform martensitically; and the third, a Ti-V alloy with an Ms below room temperature and an Md above room temperature, but known to contain w phase in the quenched condition. The compositions of these alloys are given in Table I. These alloys were cast as 5-lb experimental ingots, employing skull melting. The ingots were hot-forged into 1-in.-round bars. Two 72-in.-thick slices were cut from each bar for hardness testing; the remainder was cut into 0.252-in. tensile blanks. The tensile blanks and one hardness disc from each bar were heated in salt to a temperature 100°F above the 0 transus, held 2/2 hr, and brine quenched. X-ray analysis showed the pieces to be 100 pct 8.* *Omega cannot be distinguished from p by the technique employed. Tensile blanks were machined to size after this treatment. TO prevent transformation due to machining stresses, the shoulders and gage length were ground. True stress-true strain curves were

Jan 1, 1960

By A. R. Gregory

A shear wave velocity laboratory apparatus and techniques for testing rock samples under simulated subsurface conditions have been developed. In the apparatus, two electromechanical transducers operating in the frequency range 0.5 to 5.0 megahertz (MHz: megacycles per second) are mounted in contact with each end of the sample. Liquid-solid interfaces of Drakeol-aluminum are used as mode converters. In the generator transducer, there is total mode conversion from P-wave energy to plain S-wave energy. S-wave energy is converted back to P-wave energy in the motor transducer. Similar transducers without mode converters are used to measure P-wave velocities. The apparatus is designed for testing rock samples under axial or uniform loading in the pressure range 0 to 12,000 psi. The transducers have certain advantages over those used by King, 1 and the measurement techniques are influenced less by subjective elements than other methods previously reported. An electronic counter-timer having a resolution of 10 nanoseconds measures the transit time of ultrasonic pulses through the sample; elastic wave velocities of most homogeneous materials can be measured with errors of less than 1 percent. 5- and P-wave velocity measurements on Bandera sandstone and Solenholen limestone are reported for the axial pressure range 0 to 6,000 psi and for the uniform pressure range 0 to 10,000 psi. The influence of liquid pore saturants on P- and S-wave velocity is investigated and found to be in broad agreement with Biot's theory. In specific areas, the measurements do not conform to theory. Velocities of samples measured under axial and uniform loading are compared and, in general, velocities measured under uniform stress are higher than those measured under axial stress. Liquid pore fluids cause increases in Poisson's ratio and the bulk modulus but reduce the rigidity modulus, Young's modulus and the bulk compressibility. INTRODUCTION Ultrasonic pulse methods for measuring the shear wave velocity of rock samples in the laboratory have been gradually improved during the last few years. Early experimental pulse techniques reported by Hughes et al.2 and by Gregory 3 were beset by uncertainties in determining the first arrival of the shear wave (S-wave) energy. Much of this ambiguity was caused by the multiple modes propagated by piezoelectric crystals and by boundary conversions in the rock specimens. Shear wave velocity data obtained from the critical angle method, described by Schneider and Burton4 and used later by King and Fate sand by Gregory, 3,6 are of limited accuracy, and interpreting results is too complicated for routine laboratory work. The mode conversion method described by Jamieson and Hoskins7 was recently used by King 1 for measuring the S-wave velocities of dry and liquid-saturated rock samples. Glass-air interfaces acted as mode converters in the apparatus, and much of the compressional (P-wave) energy apparently was eliminated from the desired pure shear mode. A more detailed discussion of the current status of laboratory pulse methods applied to geological specimens is given in a review by Simmons.8 A new shear wave velocity laboratory apparatus has been developed for testing rock samples under elevated pressures. This apparatus employs liquid-solid interfaces as mode converters. The technique for generating pure shear waves at liquid-solid interfaces was developed from studies of critical angle methods.6 Two identical transducers are placed in contact with opposite ends of the rock sample, one transducer acting as an ultrasonic energy emitter or generator and the other acting as an ultrasonic energy receiver or motor. The P-wave energy emitted from the piezoelectric crystal in the generator transducer is converted into pure S-wave energy at the Drakeol-aluminum

By G. Sachs, E. J. Ripling, S. I. Liu, J. J. Lynch

It is a generally recognized fact that by repeated straining the fracture stress of any metal is reduced to a fraction of its value for static loading. The value of this fatigue strength depends upon numerous factors, such as the states of strain and stress, the limits of straining, and the number of repeated loadings or cycles The large volume of previous investigations on fatigue is concerned entirely with large numbers of cycles, say exceeding 10,000 and up to 500,000,000. However, the changes in fracture stress and fracture strain occurring after a small number of repeated loadings have attracted little attention. Apparently the only investigations of this type are those byLudwik4.5 who subjected steel, copper, and aluminum wire to repeated torsion. In each test the torque was varied between identical values in the two directions of twisting. Depending upon the magnitude of the moment, fracturing occurred after a number of cycles, up to 10,000. The results of Ludwik's tests will be discussed later Such torsion does not readily yield actual stress and strain values. Therefore a pre- liminary study was made of the effects of repeated direct stresses, that is, tension and compression stresses. Because such tests are considerably more tedious than torsion tests, only high stresses were used in the preliminary work, yielding definite changes in metal properties after a few cycles. It was found in these tests that strains could be controlled more readily than stresses in the investigated range of high stresses. This paper, consequently, deals with the effects of strains of equal magnitude but different signs. The metal was first prestrained in static tension by a certain amount then subjected to compression to yield the same amount of strain after unloading. This loading cycle was repeated up to a maximum of seven times. After various cycles, the stress-strain curves in tension were determined, up to fracturing. As material for these tests, the aluniinum alloy 24ST was selected because it exhibits a comparatively small amount of necking in the tension rest This alloy permitted, therefore rather accurate cont.rol at the high strains necessary to produce fatigue failures at less than seven cycles. The results of this invest~gation appear sufliciently interesting to extend the method of attack in various directions It is intended to study (11 the effects of cycles up to a tew thousands and (2) the effects of strains of different magnitude in tension and compression respectively 'The latter variable also includes a. a special case the effects of compressive strains.

Jan 1, 1949

By R. F. Mehl, M. Gensamer

Although a large number of X-ray photograms of cold-rolled steel have been published, two circumstances have led to the experimental work reported in this paper. The first is that no complete study, making use of the pole-figure method of Weverl, has been made of cold-rolled low-carbon steel. Wever has published pole figures of mild steel subjected to plane parallel deformation1, 2 and undoubtedly he has applied the method to cold-rolled mild steel, but the authors have not found these data published. Kurdjumow and Sachs3 have applied the method to the study of rolling and recrystallization textures in electrolytic iron; their results will be referred to later. The reason for this dearth of papers using the pole-figure method is obvious; a greater number of photograms and more analytical work (although this work is quite simple and straightforward) are required to construct a pole figure than most investigators have felt worth while, despite the fact that no other method of which the authors are aware will satisfactorily depict the orientations of the crystallites in a polycrystalline aggregate. The second circumstance that led to the work reported in this paper was the appearance of a paper by Wayne A. Sisson4 on the same subject. In his valuable study of the factors influencing the development of preferred orientations in cold-rolled mild steel, Sisson made one observation that required confirmation; that is, that at some stage of the rolling process the type of preferred orientation changed from the type that gives a photogram characterized as a "six-point" X-ray pattern to that known as a "four-point" pattern. A similar observation had been made by Tam-mann and Heinzel5, who studied the orientations developed in the rolling of steel by the specular reflection of light from the etched surface of rolled samples. These workers also found that the type of preferred orientation changed during the rolling process. The authors had some difficulty in seeing how this behavior could be consistent with modern views on the genesis of preferred orientations, particularly with those of Wever2

Jan 1, 1936

By F. H. Spedding

From thermal, metallographic, X-ray, dilatometric, and electrical resistance data a Phase diagram is proposed for the La-C system. TWO compounds are formed, body-centered-cubic Laz C, having a large range of solid solubility, and body -centered-tetrago-nal Lac2 . The former melts incongruently at 1415°C, and at 25OC it has an electrical resistivity about two and one-half times that of bure lanthanum. The latter melts congruently at 2356°C and at room temperature has an electrical resistivity about equal to that of bure lanthanum. The addition of carbon to La lowers the melting Point of La about 115' C, raises the higher (B-Y) transfomzation about 10" C and appears to have no effect on the lower ( a-0) transformation. The addition of carbon appears to lower the oxygen content in the metal and improve the machinability; however, the tendency to oxidize is increased. Two eutectics are formed in the system. The first occurs at 2.2 pct C and melts at 806" C, while the second occurs between Lac2 and C with a melting point of2271"C. PETTERSSON,~ in 1895, was the first to prepare lanthanum dicarbide by heating the oxide with carbon in an electric furnace. He showed that this yellow, crystalline but brittle carbide had a formula corresponding to LaCz and that it reacted with water with the evolution of hydrogen and hydrocarbons and the formation of the hydrated oxide. Von Stackelberg's investigation of the crystal structure of the MCz carbides showed that the lanthanum dicarbide is of the tetragonal calcium dicarbide-type structure. He found the lattice parameters were a = 3.92 and c = 6.56.* Bredig,' using X-ray methods, showed that the room-temperature form of lanthanum dicarbide is stable up to 1750 °C and that above this temperature it transformsoto a face-centered-cubic structure, a = 6.0 ± O.lA, probably of the pyrite, FeSzstruc- typ? The reported discovery of two new cerium carbides, suggested that a corresponding face-centered-cubic lanthanum monocarbide and a body-centered-cubic lanthanum sesquicarbide might exist. This paper describes work on the lanthanum-carbon system which is part of a study of the rare earth metals and their alloys now in progress in this laboratory. EXPERIMENTAL PROCEDURE Source of Materials—The lanthanum metal was prepared at the Ames Laboratory by metal1o;hermic reduction of the fluoride with calcium metal. The results of spectrographic and chemical analysis indicated the presence of 0.01 pct Y, Al, Cu, Fe, and Si; 0.02 pct Ca and Mg; 230 ppm C; and 115 ppm N. The carbon used was of two types: 1) "National Special Graphite Spectroscopic Electrodes," and

Jan 1, 1960

By C. G. Dunn, J. L. Walter

Either (100) (001] or (110) (0011 oriented secondaries, or both, depending on annealing atmosphere and material composition, grew in a matrix of 2-dimensional grains. The growth dependence of secondaries of(hkl) orientation in the iron and 0.6 pct Si-Fe is explained in terms of surface energy driving forces and the dependence of these driving forces on both (hkl) orientation and amount of oxygen at the surace. (100) [001] grains grow when suflicient oxygen is present at the gas-metal interface to make y100 the lowest (hkl) surface energy. When little or no oxygen is present at the gas -metal interface, making Y110 the lowest surface energy, (110) (001 1 grains grow. When Y100 and y110 are approximately equal but lowest among (hkl) surface energies, both (100) (0011 and (110) (0011 grains grow simultaneously. An excess of surface oxygen produces complete grain growth inhibition in high-purity iron; i.e., a 3-dimensional grain structure is retained over long annealing periods. However, a small amount of silicon in the iron reduces the growth inhibiting tendency of oxygen without altering the (hkl) surface energy relationships. Some information on annealing twins is presented. SECONDARY recrystallization in high-purity a iron, cold rolled to strip a few mils thick, was reported recently.' The present paper provides additional information on this subject, also furnishes similar information on both zone-refined iron and a high-purity 0.6 pct Si-Fe alloy, and treats the more important surface phenomena that determine to a large extent whether one or more secondary recrystallization textures will appear during annealing. Previous studies on high-purity 3 pct Si-Fe2,3 have shown the importance of (hkl) and impurity-atom dependent gas-metal surface energies on the formation of secondary recrystallization textures in high-purity material. For example, either (100) or (110) oriented grains may have the lowest surface energy depending on the amount of oxygen at the gas-metal interface, and hence the highest driving force for growth if other growth factors are the same. Another important phenomenon in high-purity material is stabilization of the matrix structure; neither impurities nor a strong matrix texture seem to be necessary when recrystallization and normal grain growth occur, developing a stable two-dimensional type grain structure. The average grain size in such a structure is usually between one and two times the specimen thickness. Consequently, most of the grains have grain boundaries terminating at exposed surfaces, and this results in gas-metal interfaces (or hkl surfaces) as well as

Jan 1, 1962

By W. D. Robertson, Raymond C. Boettner

A study was made of the change in density during the first (transient) and second (linear) stages of the creep curve of polycrystalline copper as a function of 1) stress, 2) temperature, 3) plastic strain, 4) impurity and atmosphere effects, and 5) structure, including single crystals. Voids were not observed in single crystals strained 15 pct at 500°C, or in a polycrystal-line aggregate produced by recrystallizing a single crystal, within the limit of sensitivity, Ae/e = 1 x 10-4. It appears that voids are heterogeneously nucleated at grain boundaries by an insoluble phase, or phases, which can be removed by directional solidification. The principal controlling mechanism of void growth appears to be condensation of vacancies at grain boundaries. Vacancies are transported to a boundary and condense as a consequence of the tensile stress component across the boundary, which depends on the orientation and configuration of the boundary plane and on boundary shear across ledges and other irregularities. The ultimate source of vacancies is the free surface and diffusional transport is by way of the boundary plane. PREVIOUS investigations have dealt with the nucle-ation of voids at grain boundaries under creep condition~'-~ and with the connection between grain boundary voids and subsequent brittle fracture.5-7 Growth of voids during the creep process, particularly in the transient and linear stages of creep, has not been studied with the same intensity. Therefore, it seems pertinent to investigate the process of void growth with respect to the related creep curve, and the morphology of growing voids with respect to the structure.

Jan 1, 1962

By B. R. Hollebone

The chemical action of molten anhydrous pyridinium chloride (pyridine hydrochloride) on oxy salts and ores of some Group IV and V metals are discussed-in particular zirconium, hafnium, niobium (columbium) , and tantalum. Laboratory-scale experiments are described whose results suggest that this reaction might provide a practicable means of converting ores of these metals to the anhydrous metal chlorides. Experimental results are given which provide some insight into the nature of the reactions and some of the compounds which could be present at intermediate stages. The treatment of ores of the more refractory metals is difficult and expensive and often demands the use of gaseous chlorine, hydrogen fluoride, or other reagents which are, if nothing else, expensive and dangerous to use. This situation is, of course, due to the strong metal-oxygen affinity resulting from the high charge and the small size of the metal ion which combine to produce such high lattice energy in the metal oxide as to defeat standard reduction methods. Thus, the characteristic of these metals which leads to one of their most important properties—corrosion resistance—is the main hurdle in obtaining the metal. Many common methods' for treating ores of zirconium and niobium (columbium), for example, proceed as directly as possible to the preparation of anhydrous halides. These halides are purified by now standard processes of solvent extraction, fractional distillation, and so on. This paper reports on preliminary stages in the development of a method of treating these ores—particularly of niobium—so as to prepare the anhydrous, volatile halides by the use of chemical reagents which are much more easily handled than those used at present. CHEMICAL PRINCIPLES The solvent action of aminium halides has been referred to periodically in the literature over several decades. The chemistry of pyridinium chloride has been discussed particularly by Audreith2 and Starke.3 However, since this is not familiar chemistry in its nonaqueous setting, it is perhaps well to point out some general metallurgical principles and applications. One can use, as point of departure, the fact that HC1 dissolved in pyridine is an acid very much the same as aqueous HC1. It thus gives essentially all the reactions of the HC1 with which we are familiar. However, when the ratio of HC1:pyridine reaches 1:l (a ratio far higher than is possible with H2O) the solution becomes solid C5F5NHC1, pyridinium chloride.* Inter- estingly, the acidic properties of HC1 persist in this medium, although they are manifest only in the molten state of the compound. Some typical reactions of divalent metal compounds which we have carried out in our laboratories are the following: 2PyHCl + Zn — (ZnCl2) + H2 + 2Py 2PyHCl + MnO — (MnCl2) + H2O + 2Py 2PyHCl + CuS — (CuCl2) + H2S + 2Py 2PyHCl + CaCO3 — (CaCl2) + H2O + CO2 + 2Py In these equations, the parentheses indicate a solvated compound which in water would be predominantly a hydra ted cation but which in molten PyHCl will more likely be a complex chloro-anion of the type MC14-. Some important physical properties of pyridinium chloride (PyHCl) are given in Table I. One sees from the data in Table I that at the temperature of molten pyridinium chloride both water and pyridine will boil away. Thus the system will be kept anhydrous. For this reason the reaction 2NbCl5 + 5H2O— Nb2O5 + 10HC1 has no counterpart in molten PyHCl. Instead, the chloride is made even more stable by the formation of a hexachloro complex: Nb2O5 + 12PyHC1 — 2PyHNbC16 + 5H2O + 10Py One interesting property of these complexes is their thermal instability which for the case of niobium can be illustrated as PyHNbCl6 — PyHCl + NbCl5 With a view to possible use of this chemistry in ore treatment, we have attempted to dissolve Pyrochlore (essentially FeO - Nb2O5) and recover the NbC15 from it.

Jan 1, 1968

Jan 1, 1940

Jan 1, 1940

By C. S. Simons, G. Major-Marothy, M. A. K. Grice, D. A. Dahlstrom

The vacuum filter operating variables that influence cake moisture are discussed. The influence of temperature control, particularly through application of steam to the cake, is emphasized. Results of pilot plant studies on filtration of fine hematite concentrates are presented and discussed, and are shown to support the theoretically-derived conclusions. Results on fine magnetite concentrates are also used to support the argument. The relative merits of disc and drum filters from the standpoint of cake moisture are discussed. Moisture content has always been recognized as one of the most important properties of concentrates used as pellet plant feed. Most iron ore concentrates are produced by wet methods, and are finally de-watered on filters. Obviously, a real economic advantage accrues to the ability of control the moisture content of the filter cake within the range required for optimum pellet production. Another consideration, also, has been receiving increasing attention recently. Transoceanic shippers of concentrate cargoes are critically assessing the hazards of excess moisture. The nature and magnitude of these risks have been described, ' and it appears that their elimination may require that residual moisture be somewhat lower than the limit for proper pelletization. Coarse, very free-filtering materials, such as the products of spirals, are usually best handled on top-feed types of machines. The moisture content of the cake may be held at a specified value by proper design and operation, taking into account cake thickness, air-flow rate, and drainage time. Fine-grained concentrates, with which we will be concerned here, must be filtered on Drum or Agidisc machines. With many of these materials, it is possible, by proper design, to meet cake moisture requirements with a conventional filter station. The first installations to produce high-grade pellets from magnetic taconites fell in this class. In fact, the design criteria were developed in connection with operations of Reserve Mining Co. at Silver Bay, inn.,2 and these have been verified repeatedly in other mills. The trend today, however, is toward the production of more difficultly dewatered concentrates. This is due on the one hand to the increasing attention being given to non-magnetic ores, which tend to be far slimier, and therefore much more retentive of moisture, than the magnetites. On the other hand, the pressure to improve the grade of the magnetic ores is leading to finer grinds, which also are more difficult to dewater. In the latter case, the decision to improve grade in an existing operation by finer grinding for better liberation may lead to two unattractive alternatives: 1) substantially higher bentonite consumption, plus the risk of poorer quality pellets, from high cake moisture, or 2) installation of a thermal dryer. There is, however, a third alternative. In recent papers by two of the authors3,4 it was shown that for many materials a significant decrease in cake moisture can be obtained by applying live steam to the cake face during the drying part of the filter cycle. Further, this limited drying appears to have distinct economic advantages compared to thermal drying. It is the purpose of this paper to explore the third alternative. To do this, the results of an extensive pilot study of steam filtration of a hematite flotation concentrate will be critically examined. This study was sufficiently broad so that a number of alternate suggestions (besides steaming the cake) for reducing moisture content were tested, and comparative data for both Drum and Disc filters were obtained. The work was particularly interesting since the concentrate has a high Blaine surface, and is therefore particularly difficult to dewater to the levels required. FILTER CAKE MOISTURE The significant difference between concentrate filter cake as discharged from the filter, a cargo of that same filter cake during or after shipment, and a green ball formed from that filter cake is in the relative volume of voids, or porosity. In every case, the material is a collection of small solid particles held together by the cohesive forces of a liquid. The physical properties of the aggregate are determined by the

Jan 1, 1967

By John J. Van den Broek

As the established tailings disposal techniques do not meet the requirements of today, alternative methods of disposal are explored. McIntyre Mines Ltd., Coal Div. found a solution in the construction and operation of a tailings dewatering plant. The solids are recovered from the tailings slurry by means of mechanical dewatering equipment and are then dried in a unique drying system to provide an excellent thermal fuel for a power generating station.

Jan 1, 1983

By Bain, Edgar C.

THE results are presented of an investigation to discover the fundamental atomic conditions existing in Corson's high-copper alloys hardenable by means of silicide solution and reprecipitation. The study attracted the writer because it offered a very convenient example of the general type of hardenable alloys exemplified by duralumin. Sykes' iron-tungsten and iron-molybdenum alloys and the hardenable lead-antimony. SUMMARY OF RESULTS AND CONCLUSIONS In brief, the investigation shows that very perfect crystallinity exists in the solid solutions prepared at high temperature to contain as much dissolved silicide as possible. The lattice parameter of copper is altered very little by the amount of cobalt, nickel or chromium, and silicon dissolved. The hardening by drawing at a temperature to initiate precipitation of excess silicon and metal produces a remarkable change in the atomistics of the solid solution. The old perfection of crystallinity in the solid solution is destroyed and the new atomic spacings are of variable magnitude even in one grain, and a condition in a measure resembling that found in martensite is observed. Were no particles whatever precipitated by the drawing action, still ample causes for hardness would be in evidence in the solid solution alone. The lack of plane continuity in the crystal grains would oppose slip in a very effective manner. Complete annealing restores the crystalline perfection in large measure. In these alloys even the most sensitive methods failed to reveal the characteristic pattern of the silicide precipitated by the anneal, but this was largely to be expected as the amount is relatively small.

Jan 1, 1927

By R. S. Dean

MANY studies have been made of the properties of steel produced by adding varying amounts of sponge iron to the charges used in steel-making furnaces.1-3 The results of these previous studies, however, have failed to disclose a reason for the belief of steelmakers that steel made in this way is definitely different from steel made entirely from scrap or iron melting stock. This paper deals chiefly with the structure of the sponge iron, of the wrought iron made by welding the sponge iron into blooms, and of the steel made by melting the forged and rolled blooms. It is believed that the structure of the final steel is inherited from the ore and that this inherited structure produces marked differences in the properties of the steel and explains the feeling of steelmakers which is based on their experience. Three kinds of sponge iron were used in this investigation: One made from a limonite ore reduced with natural gas, one made from a hematite ore reduced with natural gas, and one made from a magnetite ore reduced with charcoal. The sponge iron made by reduction with natural gas

Jan 1, 1935

By H. R. Deeth, C. J. Koenig

About ten years ago nepheline syenite was introduced to the ceramic industry and the material has now found application in the various branches of the industry, namely, as a vitrifying agent in white-wares and as a source of alumina and alkalies in glasses, glazes, and porcelain enamels. Spencel described the early mining and processing developments regarding this material. Since the time of his article many research papers have appeared relating to the usage of nepheline syenite but little has been published relative to subsequent mining and processing methods. A complete indexed review of the literature was issued recently by Ohio State University.2 Since "Lakefield" nepheline syenite from Blue Mountain, Ontario (Fig I); is the only commercial ceramic-grade nepheline syenite now being marketed on this continent, discussion is limited to this operation carried on by American Nepheline Limited, Lakefield, Ont., and its subsidiary in the United States, American Nepheline Cory. at Rochester, N. Y. The Deposit Blue Mountain is a long ridge rising to an elevation of about 350 ft at its highest point above the surrounding country and extending for about six miles in a northeasterly direction across Methuen township, Peterborough County. The rock of the Blue Mountain central alkaline intrusive is fine grained, light colored and of even granitic texture. The solidified mass consists predominately of the minerals albite, nepheline and microcline in order of abundance. The average mineralogical composition for the deposit obtained by a study of 112 samples taken regularly over the whole formation is as follows:3 Volumetric Mineral Per Cent Albite.................... 54 Microcline................ 20 Nepheline................ 22 Muscovite................ 2 Mafics.................... 2 (Biotite, hastingsite, magnetite) Total................... loo The mineral nepheline (or nephelite) belongs to the feldspathoid group but is lower in silica content than are the feldspars. It is a silicate of soda, potash, and alumina (NaKAl2O32SiO2). Its presence with albite (Na2oA12O3 6SiO2) and microcline (K2O A12O3 6SiO2) gives the Blue Mountain deposit an alkali content of 15 pct and an alumina content of approximately 24 pct. While this huge alkaline mass is somewhat variable mineralogically, it has a uniform chemical composition. When the iron, mostly in the form of magnetite, is removed during processing, a remarkably uniform finished product is obtained. Geological surveying has disclosed many million tons of nepheline syenite in the Blue Mountain deposit. Diamond drilling in the area where mining is now being carried out indicates a block of about one million tons.

Jan 1, 1949

By C. G. Dunn

IT is well known that plastic deformation alters many of the properties of a metal and subsequent heat-treatment partially or completely restores these properties.1 In the deformed or strained state, the metal is unstable and tends to change toward a condition called a "strain-free state." The transformation occurs through recovery, recrystallization, and grain growth-processes that may take place singly or in combination. The distortion of the lattice of an individual grain of a metal in a state of strain may be rather complex in nature, because plastic deformation produces: (I) dislocations within mosaic blocks; (2) elastic variations of the lattice spacings; and (3) gross alterations throughout the lattice, especially along slip planes, along composition planes between a grain and its mechanical twins, and along boundaries of deformation bands. These gross alterations are of the nature of bent planes or rotated regions of the crystal lattice and are revealed by a spread in the orientation of the grain. Although we cannot describe these strains and their formation accurately because of insufficient knowledge, we can, nevertheless, use the information as well as possible to obtain a better understanding of recovery processes. In recovery, the lattice of a grain is not made anew as it is in recrystallization, but is improved or mended in such a way that the basic structure remains unaltered. Until recently observations were that recovery produced no marked changes in the shapes of spots in Laue diffraction patterns, whereas recrystallization did, but now it is known for silicon ferrite2 that Laue spots may become quite sharp entirely through recovery. Consequently, the shape of Laue spots alone would not be a suitable test to distinguish between recovery and recrystallization. There is considerable evidence that the micro- structure usually does not change visibly during recovery. Absence of a visible change in the microstructure, therefore, provides a sufficient test of recovery in many cases. However, including this observation in a definition of recovery as a necessary condition (this is usually done) is unfortunate, because recovery may, as will become evident later, produce new grain boundaries that are visible not only in the microstructure but also in the macrostructure. For the present, therefore, let us say that a necessary condition for a process to be one of recovery is that the principal orientation or orientations of a deformed grain be essentially unchanged throughout the transformation toward the strain-free state. Several transformations may occur that fulfill this condition, and the nature of the distortion in a grain indicates what these must be if the lattice is to be mended in part or fully. Consequently, it will be convenient as well as

Jan 1, 1946

By Jasper L. Stuckey

GEOGRAPHICALLY, North Carolina consists of three divisions, the coastal plain on the east, the piedmont plateau in the center, and the Appalachian mountain region on the west. Geologically, the State may be divided into two main divisions, an eastern or coastal plain region, and a western or piedmont plateau and mountain region. The eastern region is underlain with unconsolidated sands, clays, marls, and shell limestones varying in age from Cretaceous to Recent. The western region is, in general, underlain with gneisses, schists, slates, sheared volcanics, and igneous intrusives of Pre-Cambrian age. In the mountain and upper piedmont portion of the western region are several areas of irregularly metamorphosed sediments of early Paleozoic age. Throughout the piedmont plateau and a part of the mountain portion of the western region, important areas are underlain with igneous intrusives of late Carboniferous age. Along the eastern edge of the piedmont plateau are two narrow belts, trending northeast-southwest, underlain with sediments of upper Triassic age. Although North Carolina contains a

Jan 1, 1947

Jan 1, 1928

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Jan 1, 1938

By Ma Guang, Huang Jinshou

In this paper we briefly describe measuring techniques and their practical use in the mining industry of China. A strain coefficient matrix of triaxial strain cell for a flat ended borehole is also introduced.

Jan 1, 1983