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By Albert J. Phillips

When brasses containing from 61 to 62.5 per cent. copper are very rapidly cooled from temperatures near their melting point to below 0" C., unusual results are obtained. These results are quite unexplainable from a consideration of the old copper-zinc constitutional diagram but they can be satisfactorily explained by means of the diagram revised by Genders and Bailey1 (Fig. 1). Experiments on a 60/40 Brass If an alloy containing 60 per cent. copper is heated to any temperature between approximately 760' C. and its melting point, it will consist entirely of beta. Upon slowly cooling, alpha will start to separate just below 760" C. Since this alpha will contain nearly 65 per cent, copper, the beta will be impoverished by its separation. As the temperature decreases the composition of the separating alpha will approach approximately 61 per cent. and the beta in contact with the alpha will maintain an equilibrium composition approaching 54.5 per cent. copper. If the rate of cooling is extremely slow, especially at the lower temperatures, stable equilibrium will be established by diffusion through the alpha and beta so that eventually 85 per cent. of the alloy will consist of alpha containing 61 per cent. copper, while 15 per cent. will be beta containing 54.5 per cent. copper. With a faster cooling rate diffusion cannot keep apace and the constituents will be cored, the alpha varying from 65 to 61 per cent. copper and the beta from 60 to 54.5 copper. In this case the amount of alpha will be less than 85 per cent. and the beta will be increased correspondingly. The general structure thus obtained is illustrated in Fig. 2. When a more rapid rate of cooling is effected by quenching in water, the alloy is retained largely in the beta form. However, the crystals of beta are usually outlined with dark fringes which at high magnifications are found to be very fine alpha-beta structures almost martensitic in appearance. The separation of this fringe can be greatly suppressed

Jan 1, 1930

By Arthur Notman

(San Francisco Meeting, September, 1915) SACRAMENTO HILL is a mass of granite porphyry intruded along a fault between Paleozoic sediments and pre-Cambrian schists in the Bisbee district, Cochise County, Arizona. The intrusion invaded both walls of the fault to a large extent, and the accompanying extensive mineralization of the Paleozoic limestones is the locus of the great high-grade copper orebodies of the Bisbee mines. Prior to 1909, although the presence of ore in the mass of the hill itself had long been suspected, systematic exploration had not been attempted. A few shallow pits on the surface here and there had disclosed some chalcocite with associated carbonates as stringers in a mass of strongly brecciated, silicified, and iron-stained porphyry. The workings in the surrounding limestones had penetrated the porphyry in a dozen or so places for some distance from the contact but had disclosed no ore. However, the rock had been largely altered to quartz and sericite and very thoroughly impregnated with pyrite and traces of the copper sulphides. A close geological study of the conditions, both surface and underground, strengthened these suspicions, and plans for prospecting the hill were made in 1909. Reference to the accompanying illustrations, Figs. 1 and 2, will give an idea of the general appearance of the surface. The mineralization is more intense in two main zones, one at the west end and the other at the east end of the hill. The outcrop of the hill is elliptical and approximately 3,000 ft. long by 1,400 ft. wide. The Sacramento shaft, which is the main hoisting shaft of the mine and situated at the east end of the hill, as shown by the accompanying map (Fig. 3), offered a convenient base for prospecting that end of the hill, while the workings from the Holbrook shaft offered a similar opportunity at the west end. The choice of level for the first work was determined by analogy with the most favorable depth for enrichment below surface observed in the other disseminated deposits of the Southwest.

Jan 8, 1915

By Henry M. Howe

This paper is a discussion of the extremely valuable one of Mathewson and Phillips, The Recrystallization of Cold-Worked Alpha Brass on Annealing,1 which not only gives us a wealth of important data reached with great intelligence, but also shows both uncommon powers of imagination and a perfectly fair spirit. Let me try to analyze some of their results, and to enunciate some of the laws to which these results point. For brevity I refer to them as "The Authors." The page numbers in parentheses refer to their paper. 1. The Visible Aspects of Recrystallization.—Plastic deformation in a single direction, as in cold-rolling, draws the grains out in that direction, that is, inequiaxes them, without destroying their apparent individuality. Each grain seems to endure the drawing out without changing either its volume or its orientation materially, for the etching tint of each grain seems to be as uniform after as before the drawing out, save for the "etch bands,"2 shown in Figs. A to D of the Authors' Plate I. As the drawn-out metal is heated progressively, on reaching a certain "disintegration temperature" these old grains seem to break up, probably into submicroscopic fragments, and this apparent disintegration is followed by a coalescence of these fragments, so that their number decreases and their size increases, till they may become very much coarser than before the drawing out. Ruder3 coarsened the grains of silicon steel in this way till single grains reached an area of 50 cm. (7.75 sq. in.). The deformation itself probably breaks each grain up into many very small fragments, but the fact that each grain continues to have a uniform etching tint different from that of its neighbors indicates that these fragments retain the initial common orientation of the grain. The apparent disintegration which we observe, then, is rather an abandonment of community of orientation for individuality of orientation, by the fragments formed earlier during the deformation. Hence we

Jan 1, 1917

By George Scott

MANY requests for information as to the possibility of washing coals to some predetermined percentage of ash or sulfur have suggested that the producers aim to satisfy some degree of purity set by the user of the fuel, rather than to attain the greatest economic benefit to all concerned. This paper is written to show that the highest economic purity of washed coal can be determined from washability studies of the raw coal, costs of mining and washing coal, and data on the effect of ash and sulphur on the value of the coal for the particular use for which it is intended. COKE FOR BLAST-FURNACE USE For purposes of illustration, we take the case of coal washed for coke to be used in the iron blast furnace. The method outlined can be made general in its application by substituting for the figures used here the actual operating figures for the particular case under consideration. In general, it costs the blast-furnace operation from 8 to 25 c. per ton of pig iron to slag out each 1 per cent. of ash introduced into the blast furnace by the coke. This figure depends on which one per cent. of ash is removed, and decreases with decrease in ash: When blast furnaces and coal mines are considered as a whole, the figure decreases to zero and then becomes negative, on account of low recovery of washed coal. Various figures1 have been given by different investigators: These figures necessarily differ, not only on account of the differences in operating costs but on account of the difference in the respective fuels as well. For the purpose of this paper, which, as explained, is to point out a method of attacking a certain problem, the figures used in the exposition of the method are of secondary importance. It is apparent that no universally applicable figures can be used, because there are none. Each plant has its own coal,2 its own operating cost, and its own conditions.

Jan 1, 1929

By Carl H. Unruh, D. L. Katz

Experimental data are presented for hydrate formation conditions for gas mixtures of carbon dioxide and methane. Equilibrium constants for carbon dioxide, defined as the mole fraction of carbon dioxide in the gas phase (dry basis) divided by the mole fraction of carhon dioxitle in the hydrate (dry basis)... were calculated usine the equilibrium constants for methane developed in an earlier paper. INTRODUCTION A series of papers have been written on gas hydrates, giving temperatures and pressures at which hydrates would form.2. 3, 4. 5, 6. 9. 12, 13, 15 Vapor-solid equilibrium constants have been developed for methane, ethane, propane and iso-butane' by which it is possible to compute for a specific gas mixture the temperature and pressure at which hydrates will form. Carbon dioxide is present in many natural gases in concentrations usually from 0.1 to 2.0 per cent. It also forms a gas hydrate with water and presumably enters the solid solution when present with a natural gas which is forming a hydrate. The equilibrium constant giving the ratio of the concentration of carbon dioxide in the gas phase to the concentration in the solid phase is required for including the effect of the carbon dioxide when computing the conditions for hydrate formation. Direct determination of the concentration of carbon dioxide in solid hydrate requires a difficult separation to be made. Therefore, this research resorted to the measurement of the temperature and pressure at which specific mixtures of methane and carbon diox- ide would form hydrates. From the equilibrium constants previously mentioned for methane, it is possible to compute the equilibrium constant for carbon dioxide, without measurement of the composition of the solid phase. Fig. 1 shows the conditions at which methane and carbon dioxide form hydrates. The methane curve FG extents to some high pressure while the carbon dioxide curve AB intersects the vapor-liquid water-liquid carbon dioxide

Jan 1, 1949

By Carl H. Unruh, D. L. Katz

Experimental data are presented for hydrate formation conditions for gas mixtures of carbon dioxide and methane. Equilibrium constants for carbon dioxide, defined as the mole fraction of carbon dioxide in the gas phase (dry basis) divided by the mole fraction of carhon dioxitle in the hydrate (dry basis)... were calculated usine the equilibrium constants for methane developed in an earlier paper. INTRODUCTION A series of papers have been written on gas hydrates, giving temperatures and pressures at which hydrates would form.2. 3, 4. 5, 6. 9. 12, 13, 15 Vapor-solid equilibrium constants have been developed for methane, ethane, propane and iso-butane' by which it is possible to compute for a specific gas mixture the temperature and pressure at which hydrates will form. Carbon dioxide is present in many natural gases in concentrations usually from 0.1 to 2.0 per cent. It also forms a gas hydrate with water and presumably enters the solid solution when present with a natural gas which is forming a hydrate. The equilibrium constant giving the ratio of the concentration of carbon dioxide in the gas phase to the concentration in the solid phase is required for including the effect of the carbon dioxide when computing the conditions for hydrate formation. Direct determination of the concentration of carbon dioxide in solid hydrate requires a difficult separation to be made. Therefore, this research resorted to the measurement of the temperature and pressure at which specific mixtures of methane and carbon diox- ide would form hydrates. From the equilibrium constants previously mentioned for methane, it is possible to compute the equilibrium constant for carbon dioxide, without measurement of the composition of the solid phase. Fig. 1 shows the conditions at which methane and carbon dioxide form hydrates. The methane curve FG extents to some high pressure while the carbon dioxide curve AB intersects the vapor-liquid water-liquid carbon dioxide

Jan 1, 1949

L. S. Austin, Denver, Colo. (communication to the Secretary) : Mr Hartman says (p. 4 of the pamphlet) that the penetration of air into the crucible of the blast-furnace " is, of course, a function of the diameter of the nozzle." To this I would emphatically take exception. Fig. 1 represents a vertical ideal section of tuyere, cruciblewalls and charge, immediately at the tuyere, in which the currents of air are represented, both in quantity and in direction, by the tortuous black-lines emanating from the nozzle-opening and passing through channels of the least resistance. As an electric current, flowing by various conductors to a common point, is carried in quantity inversely as the resistance of those conductors, so here the air ramifies through the most open cavities or channels, relatively little of it passing where the resistance due to fine materials is great. This figure represents the course of currents in the vertical plane only. As a matter of fact, they pass away in every plane, as opportunity offers. The effect of blocking or decreasing the area of the nozzleopening would certainly only decrease the quantity of air entering by that particular tuyere, without assisting penetration. The large channels (b, b, Fig. 1, for example) would still carry the larger part of the air, while again the smaller channels (a, a, a) would continue small and take no larger percentage of the air than before. These channels momentarily change, however, with the slow descent of the coke. Further on (p. 5), Mr. Hartman describes the dispersive effect of a single lump of fuel. He has only to conceive the entire spaces before the tuyere-nozzles as filled with such lumps, in order to parallel the condition of affairs I have just explained. It is where the large pieces of the charge come down, that the mass is the most open, and the blast passes most freely. On the other hand, wherever the fine ore collects combustion proceeds slowly, because of the smaller supply of air. The

Jan 1, 1899

By J. S. Miller

THIS paper describes the method of mining a steeply pitching anthracite seam on a heavy pitch in the Orchard vein in No. 1 Tunnel of the Lehigh Coal and Navigation Co. The Orchard vein in the Nesquehoning district has a thickness of about 15 ft. on the level of the gangway, which is sufficient thickness for the gangway to be driven full width in coal. Above the gangway, the vein becomes thinner and near the surface is about 8 ft. thick. The coal is of good hard quality and carries a fairly good roof. The pitch of the vein is between 65° and 70°. Usually the breast-and-pillar method has been employed in the mining of the steeply pitching veins in this section. This method produced good results as far as the mining of the breast was concerned but the recovery of the pillar was difficult as to full extraction and expensive as regards costs. To recover these pillars after the breasts were driven, three methods were commonly employed; they were known as the pillar-breast method, pillar-skipping method, and pillar-chute method. The pillar-breast method consisted in putting a battery in one corner of the pillar (Fig. 1), coupling the manways A and B of the two adjacent breasts for two or three lengths ahead of the working face of the pillar being cut, and working the pillar as a breast. This method was used by the more skilled miners of the earlier days but has practically been abandoned. A slight variation of this method is used to some extent. In this case, the pillars are left wider than ordinarily and of sufficient width for the full-width breast to be driven in and a small pillar left on each side of the pillar breast between it and the regular breasts. With the completion of the "pillar breast," the ribs are drilled full of holes, loaded, and fired.

Jan 3, 1925

By Frederick Crabtree

WHEN Professor Stock asked for a paper on the above subject, it was too late to prepare by June 1, or near that time, one that would involve any appreciable amount of experimental work or original research; but the suggestion was made that a review of the literature bearing on the subject might be submitted in good time, and that later this could be supplemented by any experimental data obtained during the summer, if experiments were carried out. In accordance with this suggestion, there are submitted the following notes on references found in the literature of recent years bearing on sulfur in gas. It is to be, understood that, ill general, these notes express the opinions of the authors whose papers are abstracted, not necessarily the opinions of the abstractors. Very little published information was found bearing directly on producer-gas sulfur, so this has been supplemented, in certain phases of the subject, by references to illuminating gas. Methods of analysis and processes for the elimination of sulfur from the gas are, without much doubt, very closely related in these two products. As in illuminating gas, sulfur is found in producer gas mainly as hydrogen sulfide, mixed with a much smaller and variable quantity of carbon bisulfide.1 The presence of minute quantities of other organic-sulfur compounds has been intimated, but no definite statement is made concerning these. The amount of sulfur present in producer gas is variable and depends on several conditions. The primary factor is the quantity of sulfur in the fuel, but the form in which the sulfur exists, the temperature of the producer, the air-steam ratio, and the efficiency of the scrubbing process are all determining factors. When the coal used contains less than 0.5 per cent. of sulfur, the sulfur in the gas will not exceed the quantity found in the average illuminating gas.2 Sulfur in producer gas may safely

Jan 9, 1919

By Henry Howe

THE data which are collected in Table 1 show that the ferrite of low-carbon steel and of electrolytic iron, like the network of hypo- and hyper-eutectoid carbon steel, inherits, either absolutely or relatively, the, grain size of the mother austenite from which it is born in cooling through the transformation range. This evidence is so abundant and concordant as to cast doubt on Prof. Jeffries' 1 hypothesis of what might be called reversed inheritance, by which he explains Mr. Ruder's observation2 that the grains of a "slug of pressed pure electrolytic iron powder"were coarser, perhaps 12,000,000µ2, after a 3-hr. exposure to 1000° C. than after a 3-hr. exposure to 1250-1300°, when they were about 35,000µs. His explanation implies a natural tendency of coarser austenite grains to yield finer ferrite ones than spring from finer austenite grains, so that the inheritance is reversed. What seems to me a simpler explanation is that the enormous grains which followed the 1000° heating were not inherited from the mother austenite, but were formed by the process of natal coarsening, by means of which Stead and Carpenter developed grains of this same order of magnitude in this same kind of material, on heating to 950° or to 1000°, the temperature used by Mr. Ruder, provided the exposure was not unduly prolonged, and it does not seem to have been in Mr. Ruder's case. That their coarsening was natal and not through inheritance is shown first by the fact that their grain coarseness was out of all proportion to their relatively low temperatures and short periods, and hence was very far in excess of the grain size which the mother austenite must have had, and second and more cogently by the fact that the shape of these coarsened grains was evidently determined by the temperature distribution which existed during and immediately after the Ar3 transformation, that during the passage from the gamma to the non-gamma state.

Jan 9, 1917

By J. W. Moody

The first Rodpeb mill ever built and placed in full scale successful operation went onstream in mid- 1960 at Marquette Cement Manufacturing Co.'s newly modernized portland cement production plant at Nashville, Tenn. It replaced a third stage of fine crushing and two 7x22-ft Compeb mills in the wet raw slurry grinding department. The Rodpeb mill at Nashville is similar in appearance to a Compeb mill but is larger. The mill, which operates in open circuit, is 9 ft in diameter and 38 ft long. The rod compartment is 12 ft long, with the rods being 11.5 ft in length and ranging in diameter from 4 in. down to about 1 in. The weight of the rod charge is 100,000 lb. The liners of the rod compartment are of the Lorain design.

Jan 4, 1963

By H. P. Bucker, M. Felsenthal, F. R. Conley

INTRODUCTION In the intensive analysis of core samples from oil raservoirs, there is a recognized need for pore sizc distribution data. Such data, if collected with adequate precision and in sufficient quantity, should contribute to a better interpretation of fluid flow phenomena than is now possible from a knowledge of permeability and porosity data alone. It is hoped, for instance, that pore size distribution data may eventually provide a useful aid for predicting whether a water flood, or other secondary recovery methods. will he successful in a given reservoir.' Apparatus tor measurlng pore size distribution by mercury injection at pressures ranging from 0 to 2,000 psi have been described in the literature.2,3,4 All of these apparatus are somewhat complex and fairly expensive. Furthermore, the callbration of some of the apparatus is not always easy. Great difficulty, for instance, was experienced in obtaining reproducible pressure-volume correction data for the mercury pump shown in one of the references. An apparatus was therefore developed which was less complicated and less expensive than those of previously described designs. This apparatus is, in some respects, an improved version of a previously described low pressure apparatus' (maximum pressure 150 psi) which did not cmploy a mercury pump but instead used a precision bore glass tube for measuring the injected volumes. Tests were performed with the apparatus from vacuum to 2,000 psi and it was observed that the apparatus furnished reproducible pressure-volume correction data. In addition. it was noted that the maximum correction was small. precision of measurement was high. and operation of the entirc apparatus was relatively easy. Although the apparatus was designed exclusively for samples of 1 in. diameter and 1 in, length or smaller, it could be modified without much difficulty for larger samples, if desired. APPARATUS Arrangement of the pore six distribution apparatus is shown schematically in Fig. I. The heart of the apparatus is a steel sample chamber surmounted by a precision bore capillary glass tube. A mercury reservoir is connected to the lower half of the sample chamber. The top of the glass tube is in communication with a

Jan 1, 1957

By John Griffen

THE distinguishing principle of the Tromp process is the use of a medium in the bath which is not stable, i.e., the solids will settle and the density of the medium increases with depth. A medium of uniform density can most easily be effected by agitation or by means which increase the viscosity of the medium. Either of these works against the sharpness of separation of coal from its impurities. The Tromp process grinds the medium solids to relative coarseness, allows them to settle downward in the bath without hindrance, and introduces horizontal currents of medium at intermediate levels between top and bottom of the bath. This prevents any accumulation of particles denser than the upper layer of the medium from which the clean coal is conveyed away or an accumulation of particles lighter than the bottom layer or medium whence the refuse is removed. In a relatively shallow bath making a two-product separation, the intermediate horizontal currents sweep these intermediate gravity materials away to be discharged with the refuse removed by the conveyor. Such a system provides a number of advantages. The gravity of separation can be changed simply by changing the density of the medium without changing particle size of medium solids or other conditions, as would be necessary with a system requiring uniform or stable density throughout the bath. Some installations in Europe separate at 1.40 sp gr on one shift, producing a superclean coal, and on the next shift reclean refuse from dry cleaning units and effect a separation at 1.80 sp gr. Medium solids may be much coarser in size consist, which reduces the viscosity of the medium and promotes its fluidity and in turn the sharpness of separation. Coarser medium solids with a more rapid settling rate are much more easily recoverable from the dilute medium rinsed from the products. The Tromp process is not limited to the use of medium solids having magnetic properties. Instal-

Jan 1, 1953

By John Griffen

THE distinguishing principle of the Tromp process is the use of a medium in the bath which is not stable, i.e., the solids will settle and the density of the medium increases with depth. A medium of uniform density can most easily be effected by agitation or by means which increase the viscosity of the medium. Either of these works against the sharpness of separation of coal from its impurities. The Tromp process grinds the medium solids to relative coarseness, allows them to settle downward in the bath without hindrance, and introduces horizontal currents of medium at intermediate levels between top and bottom of the bath. This prevents any accumulation of particles denser than the upper layer of the medium from which the clean coal is conveyed away or an accumulation of particles lighter than the bottom layer or medium whence the refuse is removed. In a relatively shallow bath making a two-product separation, the intermediate horizontal currents sweep these intermediate gravity materials away to be discharged with the refuse removed by the conveyor. Such a system provides a number of advantages. The gravity of separation can be changed simply by changing the density of the medium without changing particle size of medium solids or other conditions, as would be necessary with a system requiring uniform or stable density throughout the bath. Some installations in Europe separate at 1.40 sp gr on one shift, producing a superclean coal, and on the next shift reclean refuse from dry cleaning units and effect a separation at 1.80 sp gr. Medium solids may be much coarser in size consist, which reduces the viscosity of the medium and promotes its fluidity and in turn the sharpness of separation. Coarser medium solids with a more rapid settling rate are much more easily recoverable from the dilute medium rinsed from the products. The Tromp process is not limited to the use of medium solids having magnetic properties. Instal-

Jan 1, 1953

By Frederick Crabtree, A. R. Powell

When Professor Stoek asked for a paper on the above subject, it was too late to prepare by June 1, or near that time, one that would invoive any appreciable amount of experimental work or original research; but the suggestion was made that a review of the literature bearing on the subject might be submitted in good time, and that later this could be supplemented by any experimental data obtained during the summer, if experiments were carried out. In accordance with this suggestion, there are submitted the following notes on references found in the literature of recent years bearing on sulfur in gas. It is to be understood that, in general, these notes express the opinions of the authors whose papers are abstracted, not necessarily the opinions of the abstractors. Very little published information was found bearing directly on producer-gas sulfur, so this has been supplemented, in certain phases of the subject, by references to illuminating gas. Methods of analysis and processes for the elimination of sulfur from the gas are, without much doubt, very closely related in these two products. As in illuminating gas, sulfur is found in producer gas mainly as hydrogen sulfide, mixed with a much smaller and variable quantity of carbon bisu1fide.l The presence of minute quantities of other organic-sulfur compounds has been intimated, but no definite statement is made concerning these. The amount of sulfur present in producer gas is variable and depends on several conditions. The primary factor is the quantity of sulfur in the fuel, but the form in which the sulfur exists, the temperature of the producer, the air-steam ratio, and the efficiency of the scrubbing process are all determining factors. When the coal used contains less than 0.5 per cent. of sulfur, the sulfur in the gas will not exceed the quantity found in the average illuminating gas.2 Sulfur in producer gas may safely run higher than that in coke-oven gas, due to the lower-flame temperature

Jan 1, 1920

By S. Paul Lindau

THREE years ago it was decided by the management to granulate the matte that is produced in the smelter of the St: Joseph Lead Co. at Herculaneum, Mo., thereby doing away with a large amount of labor in handling the matte and in subsequent crushing. On Mar. 1, 1915, the granulator was put in operation and up to Jan. 1, 1916, 18,735 tons had been, granulated. The four blast furnaces have a daily output of about 280 tons of pig lead and 100 tons of matte assaying about 11.0 per cent. Pb. It is expected that projected improvements in roasting methods will eliminate more sulphur from the charge, and cut down the matte-fall, to about one-half of the present figure. The blast furnaces are tapped into movable forehearths or settlers, 6 ft. by 4 ft. by 22 in., the slag overflowing into 27-cu. ft. slag cars which are hauled to the clump by electric locomotives. Previous to the adoption of granulation, the matte was tapped from the forehearths into small slag pots which were dumped after cooling. The matte cakes were broken with sledges, and transported to the crushing plant for fine crushing and screening. Here the matte was reduced to ¼ -in. size before being fed to the roaster bins.. A Wedge and a Holthoff mechanical furnace are used for preroasting before sintering on the Dwight and Lloyd machines. The matte is returned to the furnaces as an iron flux until the .gradually accumulating copper content reaches about 7 per cent., after which it is put aside to be concentrated in a small copper blast furnace, the resultant high-grade matte-being sold. When the matte does not settle readily from the slag, two settling devices are often used, the second one being a large catch-pot, which gathers any matte that may overflow from the forehearth, the slag then overflowing from the catch-pot into the slag cars. When full of matte, the catch-pot is removed, allowed to cool, and the contents broken and crushed.

Jan 10, 1916

By R. Maddi, I. R. Kramer

The delay time for the initiation of slip was studied in single crystals of a brass, aluminum, and ß brass. A delay time for slip was found in ß brass when the specimens were tested below room temperature; however, one was not found for a brass or aluminum. A general theory for the existence of the brittle transition temperature is proposed. A LTHOUGH a considerable amount of effort has A been devoted to the study of the deformation and fracture of single crystals, the vast majority of the work was concerned with static tests or with tests carried out at relatively slow strain rates. The necessity for the study of a possible incubation time for slip becomes apparent when the various theories which have been postulated for the elucidation of the mechanism of slip are considered. The existence of an incubation period would strongly indicate that slip occurs by a process of nucleation and growth; whereas the absence of an incubation would present rather convincing evidence that slip occurs by a cataclysmic process. In addition to shedding light on the process of plastic deformation, an understanding of the early stages of plastic deformation may be helpful in finding an explanation for the brittle behavior of the body-centered metals under certain conditions. It is well known that these metals, such as iron, molybdenum, tungsten, ß brass, etc., will become brittle as the test temperature is lowered or the strain rate is increased. In spite of the fact that this subject has received considerable attention since the turn of the century, no adequate theory exists today which explains the phenomenon. In the ductile temperature range the metal breaks with a "fibrous" fracture after considerable slip has taken place. In the brittle temperature range the metal fails essentially by cleavage on the {loo) planes: however, some plastic flow is always present even in the most brittle fractures. It is possible, as will be explained later, to ascribe this brittle behavior to the length of the incubation time for slip. Clark and Wood,' using polycrystalline metals, showed that a delay time existed for the yield point in mild steels and that the delay time depended upon the applied stress. These authors stated that the delay time was observed only with those materials for which the stress-strain curve showed a definite yield point. In their work only the mild steel specimens exhibited a delay time at the yield point, while the other materials studied-type 302 stainless steel, SAE 4130 normalized steel, SAE 4130 quenched and tempered steel, 24s-T aluminum—did not show a delay time. These authors' in an extension of their work, found that as the temperature was lowered the delay time was increased. It is, then, the purpose of this investigation to measure or to set an upper limit on the delay time for plastic flow in single crystals of a brass, aluminum, and ß brass. The delay time will also be studied as a function of temperature. The incubation time may be measured by determining the length of time the specimen will support a stress without slip occurring when the stress is greater than the static critical resolved shear stress. In order to accomplish these measurements use was made of a pendulum which was so designed that a single crystal specimen could be placed at various positions along its length. When a pendulum is struck by another pendulum of the same length, an elastic wave is transmitted down the bar with the velocity of sound in the material and is reflected from the far end of the bar. The reflected wave then travels back and unloads the stress until it reaches the impacted end of the bar and the two pendulums separate. The length of time that the specimen is subjected to the stress is equal to the time it takes for the stress wave to travel twice the distance from the specimen to the end of the bar. The stress applied to the specimen is governed by the velocity of impact of the two pendulums. The stress at which the specimen first suffers plastic: deformation was determined in these experiments by examining the specimen under the microscope for the first appearance of slip lines and by measuring the residual strain after each impact. In these experiments the critical resolved shear stress was approached from the low stress side and no attempt was made to determine it exactly. To determine it exactly, it would have been necessary to find that stress at which slip would have just started. However, since the stresses were increased in rather small increments the critical stress is believed to be approached rather closely, as will be seen from the experimental results. The critical stress will be taken as the highest stress obtained before the onset of plastic deformation. The stresses

Jan 1, 1953

By C. E. Armantrout, J. A. Rowland, D. F. Walsh

THE close-packed-hexagonal structure of mag-J- nesium is converted to a ductile and malleable body-centered-cubic lattice by the addition of lithium in excess of 10 pct. Further, the density of magnesium or magnesium-base alloys is decreased by additions of lithium. The practical possibilities of such alloys as a basis for uniquely light, malleable, and ductile structural materials were pointed out by Dean in 1944' and by Hume-Rothery in 1945.2 It was apparent to these investigators, however, that more complex compositions would be required if strengths sufficient for structural applications were to be developed in these alloys. In a search for strengthening additions, various investigators w have examined a number of the ternary and more complex alloys containing magnesium and lithium. An investigation of the fundamental characteristics of these alloys was undertaken by the Bureau of Mines. The investigation was initiated with a study of the magnesium-rich corner of the equilibrium diagram for the ternary system, Mg-Li-Al. The following data from published investigations of Mg-Li-A1 alloys were available: 1—a description of isothermal sections at 20" and 400°C through the Mg-Li-A1 constitution diagram by F. I. Shamrai;' 2—a diagram by P. D. Frost et al." showing approximate phase relationships at 700°F for a number of the Mg-Li-A1 alloys; and 3—diagrams showing the constitution at 500" and 700°F for the Mg-Li-A1 alloy system published by A. Jones et al.' Where compositions and temperatures permit comparison, these diagrams show disagreement. The 700°F isotherms of Frost and Jones differ only in the placement of the phase boundaries. But Sham-rai's 400°C (752°F) isotherm shows a variation in phases as well as in phase boundaries. Although rigid comparison of these different isothermal sections might not be justifiable, it seems impossible to reconcile Shamrai's construction with the isotherms of Frost or Jones. The isothermal sections presented in this paper were prepared to determine compositions which might be suitable for age hardening and to develop the general slope and placement of the various phase boundaries in the magnesium-rich corner of the diagram. Sections at 375", 200°, and 100°C were selected for investigation. In constructing these sections, the solubility of aluminum in magnesium, as reported by W. L. Fink and L. A. Willey Vn 1948, was used at the binary Mg-A1 boundary and the solubility of lithium in magnesium was obtained from the equilibrium diagram for that system as reported by G. F. Sager and B. J. Nelson" in the same year. The solubility of magnesium in lithium was determined experimentally and conforms in general to data reported by P. Saldau and F. Shamrai." Parameters for AlLi and MgI7A1, were taken from American Society for Testing Materials X-ray diffraction data cards. Experimental Procedures Although the isothermal sections presented in this paper are not unusually complex, the experimental techniques involved in their construction are made extremely difficult by the relatively high vapor pressure of lithium and the great chemical activity of both magnesium and lithium. Because of these characteristics, which make precise control of the composition of equilibrium-treated filings practically impossible, the disappearing phase method was used in preference to the parametric method in conjunction with metallographic studies. The alloys used in this investigation were melted and cast in an atmosphere of helium using a tilting-type furnace which enclosed a steel crucible and mold in a single unit. Each portion of the charge (500 to 600 g) was cleaned carefully just before placing it in the crucible; and the charge, crucible, and entire melting apparatus were evacuated and then washed with grade A helium while preheating to approximately 100°C. The alloys were melted and chill cast in an atmosphere of helium. Alloys prepared in this way were relatively free from inclusions and a fluxing treatment was considered unnecessary. The cylindrical ingots obtained were scalped and then reduced 96 pct in area by direct extrusion, yielding % in. diam rod. Sections of the rod, approximately 3 in. long, were given equilibrium heat treatments and then sampled for metallographic examination, X-ray diffraction study, and chemical analysis. The surface of each equilibrium-treated rod was machined to a depth sufficient to insure removal of contaminated material before samples for chemical analysis or X-ray diffraction study were obtained, and all decisions on microstructure were based on the examination of the central portion of the metallographic specimen. All specimens homogenized at 375°C were analyzed after this equilibrium heat treatment. When the composition of an alloy placed it in a critical area of the 200" or 100°C isothermal section, a check chemical analysis was made on a sample taken from the alloy specimen as-heat-treated at the particular temperature. Standard chemical procedures of gravimetric analysis were used in the determination of magnesium and aluminum; lithium, potassium, and sodium were determined by flame photometer methods

Jan 1, 1956

By W. B. Gogarty, W. C. Tosch

A new recovery process for producing oil under both secondary and tertiary conditions utilizes the unique properties of micellar solutions (also known as microemulsions, swollen micelles, and soluble oils). These solutions, which displace 100 percent of the oil in the reservoir contacted, can be driven through the reservoir with water and are stable in the presence of reservoir water and rock. Basic components of micellar solutions are surfactant, hydrocarbon and water. They may also contain small amounts of electrolytes and co surfactants such as a1cohol.r. The specific reservoir application dictates the type and concentration of each component. A salient feature of [he process is the capability for mobility control. Micellar solution slug mobility, by way of viscosity control, is made equal to or less than the combined oil and water mobility. Mobility control continues with a mobility buffer that prevents drive water from contacting the micellar solution. Laboratory and field flooding have proven that the process is technically feasible and that surfactant losses by adsorption on porous media are small. Introduction projects are under way to recover the maximum amount of oil under the most favorable economic conditions.' : New techniques are being developed to increase oil recovery,3" Polymer solutions are becoming an important means of controlling mobility in a waterflood. Thermal methods such as in-situ combustion and steam injection are being used in reservoirs containing highly viscous crudes. Surfactant flooding is receiving attention as a method of reducing interfacial tension to increase recovery.*'" Exotic recovery processes have been considered primarily for ' perations. Economics are unfavorable in most cases for tertiary recovery. studies at the Denver Research Center of the Marathon oil CO. have led to a new oil recovery method.* Micellar solutions (sometimes called microemulsions, swollen micelles, and soluble oils) are used to recover oil by miscible-type waterflooding. Basically, these solutions contain surfactant, hydrocarbon, and water. The method can be used in either secondary or tertiary operations. First, thc concept of thc process is considered in terms of the requirements for an effective miscible waterflood ing operation. Next, micellar solution properties are described including structure, composition, and phase behavior with reservoir fluids. Fluid characteristics are then considered as related to mobility control, and, finally, laboratory and field results are presented to illustrate the efficiency of the process. Concept of the Process Unit displacement efficiency and conformance determine the effectiveness of any oil recovery mechanism. In theory, a miscible waterflood should be capable of a 100-percent unit displacement efficiency with a correspondingly high conformance. Requirements for the slug of a miscible waterflood include (1) 100-percent displacement of oil in the reservoir contacted, (2) controllable mobility, (3) the capability of being driven through the reservoir with water, (4) a low unit cost to enhance economics, and (5) the ability to remain stable in the presence of reservoir water and rock. Micellar solutions satisfy requirements for the slug of a miscible waterflood process. Our discovery that these solutions acted as though they were miscible by displacing all fluids in the reservoir and by being displaced by water solved the miscibility problem. Adequate mobility control is possible by variations in solution viscosity through compositional changes. Economic requirements are met since micellar solution costs below $6/bbl appear possible, Mi cellar solutions stabilize surfactant in the presence of reservoir rock and water, thus reducing the importance of the problem of surfactant loss by adsorption. Fig. 1 illustrates schematically how these solutions are used. Operations start with injection of a micellar solution slug that serves as the oil displacing agent. Next, a mobility buffer of either a water-external emulsion or water solution containing polymer (thickened water) is injected to protect the slug from water invasion. Finally, drive water (water used in a regular waterflood) is injected to propel the slug and mobility buffer through the reservoir. Reservoir oil and water are displaced ahead of the slug, and a stabilized oil and water bank develops as shown in Fig. 1. Stabilized bank saturations are independent of original oil and water saturations. This means that, for a particular type of reservoir, the displacement mechanism is the same under secondary and tertiary recovery conditions. Oil is produced first in a secondary operation. For tertiary conditions, water is produced first. Movement of the slug through the reservoir is stabilized by the mobility buffer. An unfavorable mobility ratio usually exists at the interface between the buffer and drive

Jan 1, 1969

By G. L. Kehl, Emilo Jaraiz F., J. S. Brett

The transformation of eutectoid beryllium bronze has been quantitatively investigated at 550° and 592°C, the temperature region where the products of p decomposition are a fine lamellar eutectoid and a coarse lamellar aggregate which replaces the fine eutectoid with prolonged annealing. Metallographic evidence indicates that the coarse lamellar aggregate forms preferentially in the most densely lamellated regions of the fine eutectoid and favors the hypothesis that the development of the coarse lamellar aggregate in the fine eutectoid is due to the occurence of a cellular segregation reaction. WHEN eutectoid beryllium bronze (Cu-94 pct, Be-6 pct) is isothermally transformed at high temperatures in the and y region after quenching from the fl field, the principal initial decomposition process is G one of growth of approximately spherical nodules composed of a number of lamellar colonies of the a and y phases. After the initial reaction has proceeded substantially or completely, depending on the transformation temperature, a second reaction occurs wherein the fine lamellar eutectoid is replaced by a coarser lamellar aggregate composed of the same oand yphases.' This reaction is not simply a spheroidization of the initial fine eutectoid but the nucleation and growth of a coarser, structurally different, and more stable distribution of the @and yphases. Fig. 1 illustrates the replacement of the initial fine lamellar structure by a coarse lamellar aggregate. The a phase is the dark mottled constituent; the light constituent the y phase. The phase diagram for the copper-rich end of the Cu-Be system2 is shown in Fig. 2. The a phase has the face-centered cubic structure characteristic of copper-rich solid solutions. The B phase is a disordered body-centered cubic structure, while the y phase is body-centered cubic, ordered (CsC1, B2 type). A. viswanathanS investigating Debye patterns of Cu-6 pct Be discovered that a transitory phase appeared on very rapid quenching from the /3 region which was absent when the quenching velocity was moderate. The phase could be assigned a body-centtred cubic structure with a lattice parameter of 2.876. Tempering at 100°C for 2 hr after quenching resulted in complete disappearance of the phase. The work of Fillnow and Mack' is the only previously published study of the isothermal transformation of eutectoid beryllium bronze. Their study elucidated the nature of decomposition at various subcritical temperatures in an exploratory fashion. The purpose of the research reported in this paper was principally to obtain quantitative information on the isothermal decomposition of the fl phase and to clarify the relationships existing between the fine lamellar eutectoid and the coarse lamellar aggregate. EXPERIMENTAL PROCEDURE The material used in this investigation was an almost eutectoid Cu-Be alloy bar furnished by D.J. Mack. The alloy had been melted under a protective carbon cover and centrigugally cast into a graphite mold preheated to 490 "C. Segregation was minimized by violent agitation during melting and pouring. The analysis of the casting was 93.85 pct Cu, 5.60 pet Be with traces of Si, Mg, Mn, Co, and Al. To determine the minimum soaking time necessary to insure specimen homogeneity, a number of specimens were held in the P region at 788OC for times fron 1 min to 12 hr and isothermally transformed at 550°C. Specimens betatized less than 12 min exhibited partial transformation at times shorter

Jan 1, 1961