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By Carlos G. Valenzuela

The value generally accepted for stacking-fault energy, of copper has been approximately 40 ergs per sq cm based on Fullman's2 value for the coherent twin-boundary energy and the assumption that is twice the twin boundary energy However, Thornton and coworkers8 determined that the lower limit of for copper is approximately 60 ergs per sq cm, based on measurements of dislocation-node radii. They suggested that the assumption of = 2t is invalid. It is the purpose of this note to present results which indicate that the values of obtained by measurement of twin-grain boundary intersections and the values obtained by measurement of dislocation-node radii are actually compatible. The most reliable values for of the a brasses, based on electron-microscope observation of dislocation nodes, are probably those values reported by Smallman and Green6 who applied the Siems correction (1961) to data obtained by Howie and Swann.3 These values shown in Fig. 1 give an extrapolated value of approximately 70 ergs per sq cm for pure copper. In the present work, Fullman's method for determining the stacking-fault energy of copper was extended to the a brasses. High-purity copper (99.999 pet) and high-purity zinc (99.999 pet) were mixed in proportioned amounts and melted in sealed and evacuated quartz tubes. The alloys were homogenized for a week at 750°C and chemically analyzed by means of X-ray fluorescence. These alloys, along with a specimen of pure copper, were rolled to 98 pet reduction and a thickness of 0.009 in., resealed, and annealed for 40 hr at 715°C. Values for the ratio of twin-boundary energy to the grain-boundary energy, it gb, were obtained from measurements of dihedral angles formed at the intersections of twin boundaries and grain boundaries by using Fullman's2 mechanical analogy of surface tensions acting at the intersection of an annealing twin and a grain boundary. The angles between the twin traces and the grain boundaries were measured for a large number of twin-grain boundary intersections at a magnification of X500 using a rotating mechanical stage on a Reichert metallograph. The rotary stage has a calibrated angle scale with vernier so that measurements can be made to 0.1 deg. The mean twin-grain boundary energy and standard deviation were calculated for copper and each of the brasses by the use of an IBM 7072 computer. It was found that the mean value of gb stabilized after approximately 100 twin-angle measurements. This was determined by plotting the mean against the number of angles measured. Since the measured angles deviate from true dihedral angles, a correction factor for grain orientation, discussed below, was applied. The stacking-fault energy was then calculated from these values and the values of grain-boundary energy derived by Taylor.7 The data obtained are tabulated in Table I. Values for stacking-fault energy are plotted in Fig. 1. The value of gb for the specimen of 1.03 pet Zn is close to the value obtained by Fullman2 for OFHC (99.98 pet) copper, 0.045. It is believed that the purity of the copper affects gb significantly. The 99.999 pet purity Cu used in this investigation yielded a value of yt/ygb, 0.76, which is much higher than that obtained by Fullman. Additional evidence suggesting that the purity of

Jan 1, 1965

It has been established that molybdenum sesquisulphide, not molybdenite, is in equilibrium with molybdenum metal and sulphur vapor in the vicinity of 1100°C. The S2 pressure for this system has been obtained using the Knudsen orifice method and the standard free energy for the dissociation of S2. THIS work was undertaken to help in determining the thermodynamic properties of the molybdenum sulphide which is in equilibrium with metallic molybdenum and sulphur vapor in the temperature range 1025" to 1150°C. From the results of MontoroL and of Parravano and Malquori' molybdenite would be expected to be in equilibrium with molybdenum metal, while the results of Guichard indicate that a lower sulphide must be in equilibrium with the metal. Thus it was concluded that the problem warranted reconsideration, especially in view of the suspiciously low temperature independent term for the standard free-energy function for the reaction MoS² Mo + S,. The reaction was calculated and duly noted as being low by Richardson and Jeffes,' using the data of Parravano and Malquori.' Experimental Method The general method used in this investigation is that of the Knudsen orifice method for the determination of equilibrium pressure. The apparatus and technique are similar to those described for the determination of the vapor pressure of silver.% owever, a closed-end McDanel tube instead of fused silica was used to maintain the vacuum, a molybdenum effusion cell with a replaceable lid was employed instead of a silica cell, and a titanium getter maintained at run temperature was used to assure that no oxidation of the molybdenum or molybdenum sulphide was taking place. All runs were made at a residual pressure less than 10-5 mm Hg. The data are given in Table I. Runs 1 through 13 were obtained using molybdenite, analyzed 98.5 pct, from the Molybdenum Corp. of America. The remaining runs were done with a sample from the Climax Molybdenum Corp. which was their grade No. 3 and analyzed 59.87 pct Mo. The weight loss of the cell during heating up and cooling down was subtracted from the total weight loss of the cell during the run. Also, when the tem- perature was changed, the Knudsen cell was placed in the vacuum chamber and heated at temperature for several hours in order to allow the sulphide and the metal to adjust their compositions to the equilibrium values, to desorb or adsorb gases into or from the molybdenum cell itself, and to desorb any water from the molybdenum sulphide or molybdenum powder inside the cell. Water may have been adsorbed inside the cell because, after each run, the top of the cell was removed and the material in the cell was stirred to insure that a layer of molybdenum metal would not build up and obstruct the passage of sulphur vapor into the gas phase. It was established that the molybdenum cell alone decreased in weight an inappreciable amount when heated at the highest run temperature for long periods of time. There are two questions to be answered before the data in Table I can be used to calculate thermodynamic functions: 1—Which molybdenum sulphide is in equilibrium with molybdenum metal and sulphur vapor? 2—What sulphur species are present in the vapor phase? It can be assumed safely that no molybdenum is vaporized, since its vapor pressure is almost negligible at these temperatures. It will be shown subsequently that no sulphide of molybdenum is volatile. Question 1 was answered in the following way: The especially purified molybdenite, obtained from the suppliers mentioned previously, was charged

Jan 1, 1956

By R. M. Rose, D. P. Ferriss, J. Wulff

Single crystals of tantalum were grown by multipass zone melting in an electron beam apparatus. Tension tests of these crystals at 4.2 x 10&apos;* per sec-gave a resolved louler yield stress of 7300 psi at with a chisel edge; total uniform deformation increased from 1 to 2 pct at 77°K to over 20 pct at 300°K. This, and slip traces, indicated that deformation is more inhomogeneous at lower temperatures. Deformation occurred exclusively by slip in <III> directions, on planes in the <111> zones. Cross slip was frequent, particularly for those orientations where the resolved shear stress on the cross system was comparable with that on the primary plane. The existence and magnitude of the upper yield point were found to be sensitive to orientation. This effect was related to the circumvention of dislocations which were "locked" by interstitial atoms, by double cross slip, or composite slip, of screw dislocations. Prestrainirg at 300°K did not remove the upper yield point in subsequent tension at 77°K. Also, this treatment was found to cause yield points, where none existed for the unprestrained material. This behavior was also rationalized in terms of the circumvention mechanism. The mechanical properties of polycrystalline tantalum have been investigated by several workers,1"4 and may be summarized by pointing out the following features: a) Sharp rise of yield stress with decreasing temperature below room temperature. b) Response to strain aging at 300" to 400"C. c) Yielding with upper and lower yield-point phenomenon at and below room temperature. d) Low strain hardening below room temperature. e) Reluctance to twin except at very high strain rate. Furthermore, tantalum is ductile at ordinary strain rates as low as 4.2"K.&apos; This feature, in particular, makes tantalum unique among the high melting point, bee transition metals of Groups V and VI in the periodic system. Therefore, a more fundamental and detailed knowledge of the low-tempera- ture deformation of tantalum is required. Since high purity and the absence of grain boundary effects make such a study most productive and unambiguous, the method of electron beam zone melting was selected for the preparation of test specimens. This technique has the further advantage that crystals may be seeded in order to obtain any desired orientation. EXPERIMENTAL The electron beam zone-melting equipment was constructed as a modification of that described by Calverley, Davis, and Lever? All crystals were made by three passes of the molten zone at 4 mm per min to achieve an optimum purity commensurate with economy of time and material. Table I reports the chemical analyses of the starting and refined metal. It will be noted that there remain some 50 to 70 wt ppm of interstitial elements, while all substi-tutional elements have been removed by evaporation. Tungsten is picked up by evaporation of the cathode filament wire. Crystal seeding was normally successful within 3 deg, and the orientation of all crystals are given in the standard stereographic triangle in Fig. 1. Tensile bars were prepared from the crystals by centerless grinding to the shape in Fig. 2. Specimens were then electropolished to remove 10 pct of the diameter in order to remove worked material and to prepare a metallographic surface for subsequent deformation trace observations. All specimens were held in the split bushing grips as indicated in the cross section view of Fig. 2. All tests were made at a strain rate of 2 112 pct per min in an Instron testing machine.

Jan 1, 1962

By J. B. Darby, P. A. Beck

IN a previous publication,&apos; the 1200°C isothermal section of the Cr-Mo-CO system was surveyed. It was found that starting from the binary (Cr,Co)a, the u phase extends deep into the ternary system in the form of a narrow band, which, when extrapo-

Jan 1, 1956

By L. D. Ricketts

AN older man looks back, perhaps wistfully, on a long and rather active experience, and possibly a popular and brief glimpse of some contrast between past and present may hold your attention for a few brief moments and prove useful. In the late nineties an engineer was .called on to de- sign and build two copper ore concentrating mills of 400 tons average daily capacity. There were larger mills than this at Washoe and elsewhere, but a 400 ton&apos; mill was a large one as mills went over thirty years ago, and one might say a large mill of those days could crush a ton of copper ore in 216 seconds. In the mills I refer to steel construction and the conveying belts were introduced into the copper industry and rein- forced concrete came shortly after. Since then we in the West have ever been faced with a constantly de- creasing tenor in the grade of our copper ores and a constantly increasing demand for our product, and we have therefore been obliged to call for far larger castings and finished machines than were formerly used. The mechanical engineer has also enabled us to accomplish notable economies in power generation and distribution. Ore handling and crushing have been simplified and through the introduction of reagents to induce physical or chemical reactions, or both, our older methods have been vastly improved or even supplanted by new and better ones and our recoveries greatly improved.

Jan 1, 1929

By Henry P. Chandler

Tripoli is the general name for a number of fine-grained, lightweight, friable, minutely porous, forms of decomposed siliceous rock, probably derived from siliceous limestones or calcareous cherts. Tripoli is often confused, both in the trade and technical literature, with tripolite, a diatomaceous earth (diatomite), found in Tripoli, North Africa. A material found near Seneca, Mo., resembling tripolite was incorrectly termed "tripoli." This name has persisted and now has a definite physical and trade meaning. However, tripoli contains no diatoms, is of an entirely different origin, and has chemical and physical properties different from those of tripolite. There are two distinct types of tripoli in the United States; that from the Missouri-Oklahoma field and that from the Southern Illinois field. Commercially the term "tripoli" is applied to the material from the Missouri-Oklahoma field, while the material from the Southern Illinois area is often referred to as "amorphous" or "soft" silica. Material similar to the Missouri-Oklahoma tripoli, but finer grained, occurs in northwestern Arkansas. In its Minerals Yearbook the Federal Bureau of Mines groups statistically under "natural silica abrasives," tripoli from these producing areas and rottenstone from Pennsylvania. The justification for this grouping is the similarity of use. Composition and Physical Properties Commercial tripoli contains 97 to 99 pet SiO2. The remainder is mostly alumina, iron, lime, soda, and potash, some of which may impart desirable physical properties to the material. Variations in the chemical composition of tripoli are not as important as its physical characteristics. The color of tripoli varies from white to cream, brown, rose, and red, the variations from white being the result of iron deposited from percolating surface waters. The commercial varieties of tripoli mined in the Missouri-Oklahoma area are designated as cream and rose. Other physical properties of the tripoli from this area are: Free quartz, less than 0.5 pct; oil absorption, 50.71 to 53.14 pct; water absorption of the crude tripoli, about 38 pct, and of prepared material, about 52 pct; fracture, uneven to conchoidal; specific gravity, 2.15 to 2.62; weight per cubic foot crude, 35 lb, ground, 55 lb; fusion point, 3,225° to 3,300°F; and refractive index, 1.54. Tripoli occupies about 1 cu yd to the short ton in place and about 1.5 cu yd when broken. Packed for shipment, the powdered material occupies about 33 cu ft to the ton. Its value and usefulness depend primarily on a low content of crystalline silica, size of the natural particles, absorption, and color. Some beds in the Missouri-Oklahoma area are of sufficiently compact material that large, fairly strong blocks may be removed. These find a market as filter blocks and have been used for building material. In the Southern Illinois field the color of the material is the important physical property; pure white is preferred. The rottenstone mined in Pennsylvania is of higher density and lower in silica content than the various types of tripoli. Its composition approximates 60 pct silica, 18 pct alumina, 9 pct iron oxide, 8 pct alkalies, with small amounts of lime and magnesia. The material apparently is a ferruginous and siliceous shale, having properties rendering it suitable as an abrasive or as a filter for paint, rubber, and plastics.

Jan 1, 1960

By M. R. J. Wyllie

The relationship between the electromotive force (E.M.F.) across a shale barrier and the concentrations of sodium chloride solutions on either side has been investigated. It is shown that the action of a shale barrier is analogous to a glass membrane separating two acid solutions of different hydrogen ion concentrations. The shale behaves as a sodium electrode and is responsive to the activities of the sodium ions in the two solutions in such a way that the potential can be calculated by means of the Nernst equation. This conclusion is confirmed by laboratory experiments. In a borehole the total E.M.F. of a shale cell is the algebraic sum of the ~otential across the shale and a boundary potential. The relationship between total E.M.F. and the resistivity ratio of two sodium chloride solutions is indicated for a number of formation temperatures. The E.M.F. thus predicted is then compared with the .elf potential read from an electric log and good agreement is demonstrated. Based on both the self potential and resistivity curves of the electrical log. a method is given for calculating connate water content in a bed having in-tergranular porosity and containing both connate water and hydrocarbons. INTRODUCTION The first paper on electrical well logging by C. and M. Schlumberger and E. G. Leonardon in 1934&apos; attributed the self potential curve principally to streaming potentials, i.e. to electroki-netic effects. Almost immediately great difficulties were encountered in reconciling many of the curves they obtained with this interpretation. and a ~econd paper&apos; by the same authors soon appeared. In this second paper self potentials were attributed to the combined effects of streaming potentials and electrochemical potentials, the electrochemical potential being considered the result mainly of the interaction of fluids of differing salt concentrations, i.e. a boundary potential, and partly of potentials set up at the faces of impermeable materials. Some experiments involving a gray clay for the impermeable material were quated. The Schlumbergers and Leonardon deduced from the equation for a simple boundary ~otential that the electrochemical potential, as opposed to the electrokinetic potential, could be expressed in the form E=Klog- .......1 pe where K is a constant, pm the mud resistivity. p, the resistivity of the connate water in a porous bed. However, no general expression for the constant K was obtained. Although the literature between 1934 and 1943 contains a number of quotations of their results, the valuable work of the Schlumbergers and Leonardon was not extended so that the electrochemical potential has been generally attributed wholly to boundary potentials between the mud in the borehole and the connate waters in porous formations. Unfortunately, however, the fundamental premise of all these papers, that a boundary potential can give rise to current flow in a borehole, is thermodynamically untenable. As will be shown. the fact that the electrochemical potential can be fairly accurately express as E = K log pm/pc, a form in which a boundary potential may also be written, is partly fortuitous. The boundary potential is indeed an integral part of the expression for the electrochemical potential in a horehole, but in magnitude it represents only about 20% of the total potential. In 1943 an important step in the elucidation of electrochemical potentials was made by Mounce and Rust3 who showed that if a wall of shale separated two compartments which contained saline solutions of different concentrations, and if the two solutions were themselves brought into contact in the pores of a porous inert membrane (such as unglazed porcelain) a current flowed through the shale and saline solutions. The direction of positive current was from the shale into the more dilute solution. The paper of Mounce and Rust, while repeating some of the observations of the Schlumbergers and Leonardon, seems to be the first to show that the shale was the seat of a genuine electrochemical effect capable of causing current flow. In the same paper Mounce and Rust pointed out the similarity between the fundamental conditions of their experiment and the conditions which existed when a bed of shale in the ground was simultaneously in contact with a porous sand containing saline connate water and mud fluid of salinity different from that of the water in the sand. Since it is now generally recognized that the S.P. curve measures ohmic potential changes in the mud fluid in the well bore resulting from changes in current flow, it is apparent that currents having their origin in the electrochemical interaction of mud filtrate and connate waters with shale beds are a very important portion of the total S.P. The work of Mounce and Rusta and others appears to indicate that, in general, the electrochemical portion of a particular kick on a S.P. curve far exceeds any electrokinetic potentials resulting either from streaming potentials or Dorn effects. The Dorn effect, or sedimentation potential. arises when small particles are allowed to fall through certain fluids under the influence of gravity. a difference of potential being observe? between two electrodes placed at different levels in the stream of falling particles. The Dorn effect is unlikely to affect seriously the S.P. curve as now measured. A successful analysis of the electrochemical aspects of the S.P. log should

Jan 1, 1949

By M. R. J. Wyllie

The relationship between the electromotive force (E.M.F.) across a shale barrier and the concentrations of sodium chloride solutions on either side has been investigated. It is shown that the action of a shale barrier is analogous to a glass membrane separating two acid solutions of different hydrogen ion concentrations. The shale behaves as a sodium electrode and is responsive to the activities of the sodium ions in the two solutions in such a way that the potential can be calculated by means of the Nernst equation. This conclusion is confirmed by laboratory experiments. In a borehole the total E.M.F. of a shale cell is the algebraic sum of the ~otential across the shale and a boundary potential. The relationship between total E.M.F. and the resistivity ratio of two sodium chloride solutions is indicated for a number of formation temperatures. The E.M.F. thus predicted is then compared with the .elf potential read from an electric log and good agreement is demonstrated. Based on both the self potential and resistivity curves of the electrical log. a method is given for calculating connate water content in a bed having in-tergranular porosity and containing both connate water and hydrocarbons. INTRODUCTION The first paper on electrical well logging by C. and M. Schlumberger and E. G. Leonardon in 1934&apos; attributed the self potential curve principally to streaming potentials, i.e. to electroki-netic effects. Almost immediately great difficulties were encountered in reconciling many of the curves they obtained with this interpretation. and a ~econd paper&apos; by the same authors soon appeared. In this second paper self potentials were attributed to the combined effects of streaming potentials and electrochemical potentials, the electrochemical potential being considered the result mainly of the interaction of fluids of differing salt concentrations, i.e. a boundary potential, and partly of potentials set up at the faces of impermeable materials. Some experiments involving a gray clay for the impermeable material were quated. The Schlumbergers and Leonardon deduced from the equation for a simple boundary ~otential that the electrochemical potential, as opposed to the electrokinetic potential, could be expressed in the form E=Klog- .......1 pe where K is a constant, pm the mud resistivity. p, the resistivity of the connate water in a porous bed. However, no general expression for the constant K was obtained. Although the literature between 1934 and 1943 contains a number of quotations of their results, the valuable work of the Schlumbergers and Leonardon was not extended so that the electrochemical potential has been generally attributed wholly to boundary potentials between the mud in the borehole and the connate waters in porous formations. Unfortunately, however, the fundamental premise of all these papers, that a boundary potential can give rise to current flow in a borehole, is thermodynamically untenable. As will be shown. the fact that the electrochemical potential can be fairly accurately express as E = K log pm/pc, a form in which a boundary potential may also be written, is partly fortuitous. The boundary potential is indeed an integral part of the expression for the electrochemical potential in a horehole, but in magnitude it represents only about 20% of the total potential. In 1943 an important step in the elucidation of electrochemical potentials was made by Mounce and Rust3 who showed that if a wall of shale separated two compartments which contained saline solutions of different concentrations, and if the two solutions were themselves brought into contact in the pores of a porous inert membrane (such as unglazed porcelain) a current flowed through the shale and saline solutions. The direction of positive current was from the shale into the more dilute solution. The paper of Mounce and Rust, while repeating some of the observations of the Schlumbergers and Leonardon, seems to be the first to show that the shale was the seat of a genuine electrochemical effect capable of causing current flow. In the same paper Mounce and Rust pointed out the similarity between the fundamental conditions of their experiment and the conditions which existed when a bed of shale in the ground was simultaneously in contact with a porous sand containing saline connate water and mud fluid of salinity different from that of the water in the sand. Since it is now generally recognized that the S.P. curve measures ohmic potential changes in the mud fluid in the well bore resulting from changes in current flow, it is apparent that currents having their origin in the electrochemical interaction of mud filtrate and connate waters with shale beds are a very important portion of the total S.P. The work of Mounce and Rusta and others appears to indicate that, in general, the electrochemical portion of a particular kick on a S.P. curve far exceeds any electrokinetic potentials resulting either from streaming potentials or Dorn effects. The Dorn effect, or sedimentation potential. arises when small particles are allowed to fall through certain fluids under the influence of gravity. a difference of potential being observe? between two electrodes placed at different levels in the stream of falling particles. The Dorn effect is unlikely to affect seriously the S.P. curve as now measured. A successful analysis of the electrochemical aspects of the S.P. log should

Jan 1, 1949

By JOHN R. SUMAN

TONIGHT I want to speak of the current problems and the postwar difficulties facing American industry. American industry has done an outstanding job in adjusting its operations to wartime necessity. The national income for 1942 was nearly $120,000,090,000 and of this outlay approximately $55,000,000,000 went for war material. The enormity of the expenditures for war material is indicated by the fact that the expenditures for war purposes alone were greater than the annual gross national income in the period 1931-34. This tremendous production job in turning out a record output of war products was accomplished by industry in spite of a large number of restraining and hampering influences, and I want to mention several of the more important problems.

Jan 1, 1943

By F. D. George, M. J. Salkind

Al3Ni whisker-reinforced aluminum was found to exhibit good Charpy impact toughness and little notch sensitivity even though its room-temperature tensile elongation parallel to the whiskers is only 2 pct. This impact behavior was maintained d liquid nitrogen temperature (-196"C). It is postulated that this behavior is due primarily to the presence of the continuous aluminum matrix which provides sufficient 10calized ductility in the vicinity of the crack tip to absorb considerable energy from the advancing crack. The impact behavior of Al-Alni was found to be quite anisotropic. Of six orientations studied, the transverse orientation having the notch normal to the whisker axis was found to exhibit the lowest impact energy, whereas the transverse orientation having the notch parallel to the whisker axis was found to exhibit the highest impact energy. A significant differnce was noted between the impact behavior of material containing needlelike whiskers and that containing bladelike whiskers. Only two of the six orientations studied exhibited complete fracture for the material containing needlelike whiskers. On the other had, most of the specimens containing bladelike whiskers exhibited complete fracture. It was postulated that the bladelike whiskers block transverse flow, thus reducing the amount of plastic deformation ahead of the crack tip. One of the more significant advantages of composite materials is the prospect of combining high strength with toughness. In general, toughness is associated with materials which exhibit considerable ductility and can deform plastically in the presence of a stress concentration. Very strong materials which resist plastic deformation generally exhibit low toughness. At first glance, then, it would appear as though strength and toughness are mutually incompatible so that useful engineering materials would have to be a compromise between the two. One approach to the problem of combining the high intrinsic strength of ceramics with the toughness of metals was to mix them together to form a cermet. Unfortunately, the toughness of cermets was found to be rather disappointing. Whisker reinforcement of metals, however, appears to be a more promising approach. It has been demonstrated that whisker-reinforced metals produced by unidirectional solidification exhibit enhanced strength due to the presence of high strength nonmetallic whiskers. The total strain capacity of these composites in the direction of fiber alignment is limited to that of the fibers, the matrix being unable to carry the load once the fibers have failed. A characteristic, then, of whisker composites is low ductility in the direction of whisker alignment, on the order of a few percent elongation. This low elongation, which is usually associated with brittle behavior, should not be taken as an indication of low toughness. Such a material can exhibit significant ductility in directions other than parallel to the fibers7 and can therefore possess significant intrinsic toughness. Toughness in a fiber-reinforced metal is derived from several mechanisms. The first is due to the toughness of the matrix itself. A continuous ductile metal matrix can act as an effective crack arrest medium by undergoing localized plastic deformation. Cracks initiated from the surface of the composite or from a brittle fiber failure must travel through the matrix before reaching another brittle phase particle. A second crack arrest mechanism peculiar to fiber composites is due to the fact that, as a crack travels through the matrix and approaches a fiber, the plastic deformation ahead of the crack tip will result in loading of the fiber. This causes the matrix shear strength in the plastic zone to be apparently higher, thus extracting more energy from the crack and diverting the crack at an angle to the original direction of propagation. A third crack arrest mechanism occurs in fiber composites which exhibit a weak bond between fiber and matrix. The idea was proposed by Cook and Gordons that if a crack propagating transversely in a fiber composite were made to turn and run along the fibers by decohesion of the fiber-matrix bond, then toughness would be imparted by the blunting of the crack tip and the creation of new surfaces. The last mechanism, interfacial decohesion, is commonly noted in naturally occurring fiber composites such as wood, bone, and bamboo, and has been observed in man-made composites such as glass fiber-reinforced resins,g silica fiber-reinforced aluminum," laminated steel," and tungsten and silica fiber-reinforced electroplated copper.&apos;&apos; The first mechanism, crack arrest by plastic deformation in the matrix, has been noted in tungsten wire reinforced cast copper." The purpose of this investigation was to quantitatively assess the toughness of a whisker-reinforced metal as a function of orientation. Previous investigation considered only cracks propagating nominally perpendicular to the reinforcement. In this investigation, crack propagation in three mutually perpendicular directions as well as three intermediate orientations was investigated. The system chosen for study was the unidirectionally solidified A1-A13Ni eu-tectic alloy which has a microstructure consisting of 10 pct by volume of A13Ni whiskers in a matrix of aluminum This material exhibits two different kinds of whisker morphology, depending upon the rate at which it is solidified.&apos; At low rates of solidification (less than 2 cm per hr) the whiskers are bladelike, whereas at higher rates of solidification they are

Jan 1, 1969

THE strike and dip of bedded formations is readily determined by trigonometry if some marker horizon is intercepted by three holes. If no marker can be identified and if orientation of the cores is unknown, as is the usual case in diamond drilling, the determination still can be made readily by the use of a stereonet if the bearing, inclination, and angle the bedding makes with the core axis is known for each of the three holes. Such determination, valid only if the bedding orientation is fairly uniform within the area drilled, is considered simpler, faster, and more effective than any solution previously published. Method: The steps of this procedure are as follows: 1) Mark north and south poles on tracing paper placed over stereonet.* 2) Plot the three diamond drillholes by drawing a line from the center of the net in the direction of the bearings of the holes. Then rotate the paper until each line, in turn, lies along the equatorial diameter of the net; the end of each line is determined by the inclination of the hole measured in degrees from the periphery toward the center of the net along the equatorial diameter. Fig. 1 illustrates a vertical hole and a hole inclined at —23" due east. 3) With the projection of one diamond drillhole along the equatorial diameter, measure from the end of the hole, to the east and then to the west, a dis- tance in degrees equal to the core axis-bedding plane angle. Find two more points by measuring the same number of degrees north then south along the great circle from the end of the drillhole. Draw a circle, the center somewhere along the direction of the projection of the drillhole, to connect these four points. Draw circles for the other two diamond drillholes in the same manner. See Fig. 1 for two circles representing core axis-bedding plane angles of 35" and 23" and Fig. 2 for these plus a third circle representing a core axis-bedding angle of 42" in a hole bearing S 50 W inclined at —52". 4) Rotate the tracing paper until one great circle on the stereonet is found which is tangent to all three of the circles or parts of circles derived in the previous step. Trace this great circle on the paper and join its ends with a straight line passing through the center of the net. The bearing of this line is the strike of the bedding. In Fig. 2 the bedding strikes N 77 E. 5) Rotate the paper until the strike is along the polar diameter of the net. The dip of the bedding is determined by measuring along the equatorial diameter the distance in degrees from the periphery of the net to the great circle derived in step 4. The dip of plane illustrated in Fig. 2 is 55" to the N 13 W. Fig. 3 indicates the solution for three holes whose bearings and inclinations are N 20 W and —43o, due E and —30°, S 30 W and 23" with core axis-bedding angles of 30°, 50°, and 43" respectively. The bedding (stippled area) strikes N 44 W and dips 70" to the southwest.

Jan 1, 1956

By Samuel Storchheim

IT was noted that variations existed in the magnetic properties, namely, coercive force, He, and rema-nence, Br, of 18/8 stainless steel wires of the same analysis when these wires were given the same percentage of reductiori of area at different rates of reduction. In order to determine the extent of these variations, a program was initiated whereby commercial 302 and 304 stainless steels were drawn with a wide variation of speeds. Ultimate tensile strengths and specific resistances, as well as the Hc-BT measurements, were determined. If variations of considerable magnitude were found, it was thought that the knowledge accrued from the investigation could probably aid in determining the particular drawing speed required to obtain desired properties for a given specification for a particular analysis of wire. Drawing Procedure Two specimens (set I, No. 302 and No. 304), the chemical analyses of which are given in Table I, were drawn at different speeds, namely, 45 to 3900 ft per min, directly from 0.016 in. diam wire to 0.004 in. diam wire, a 93.7 pct reduction of area. To obtain this high percentage of reduction, the wire at 0.016 in. was softened by annealing at 1150°C. It was then strung in a No. 16CF variable speed Vaughn drawing unit and passed through 13 B.&S. gage dies of successively smaller diameter, as shown in the accompanying table. Following this step, several hundred feet of the wire was drawn, at a particular speed, through the dies and wound upon a spool. Once the sample of wire was drawn at the desired speed, the spool with the finished sample was removed, tagged for later identification, and an empty spool was placed in the machine. Another wire sample was drawn at a different speed, after making the necessary adjustments upon the Vaughn unit. At the greater speeds, several thousand feet of sample were drawn to insure that the wire to be used for testing would be uniform. This was done because the desired speed was not reached instantly; the wire taking a short while to attain the required drawing rate. All speed measurements were made by placing a tachometer against one of the machine&apos;s pulleys during the actual drawing of the specimens. 84.4 pct reduction of area. The 0.072 in. diameter wire was also annealed at 1150°C. The process of obtaining samples was the same as described above. The only difference between the two was that the rates involved were not as extensive, set II covering a range of 625 to 1150 ft per min. Tensile tests were carried out for the 0.004 in. diam wires on a horizontal Scott Tensile Tester, while tensile tests for the 0.028 in. diam wires were made on a vertical Scott Tensile Tester. Each value listed in the tables represented the average of five samples with a maximum deviation of approximately 3 pct among the samples. Resistance per foot of the wires was determined by use of standard bridges accurate to the nearest hundreth of an ohm for the 0.004 in. wire, and to the nearest thousandth of an ohm for the 0.028 in. wire. The resistances per foot were then converted to resistivities by use of the following equation: P = RxCM where R is the resistance per ft in ohms per ft; CM, the area in circular mils; and P, the resistivity in ohms—CM. The values listed in the tables likewise

Jan 1, 1952

By F. von Gemmingen, E. J. Fasiska, L. Zwell

EARLIER studies of the dependence of creep on structure1 and of the dependence of creep rupture on creep behavior2 did not include detailed discussion of the phases present in the specimens under examination. It is of interest to determine the nature and amounts of such phases present since it is well known that these are dependent on composition, heat treatment and creep conditions.3 This investigation has therefore been undertaken to identify these constituents and to determine their relative amounts. This report presents the results of this investigation and describes an improved "extraction replica" technique developed in the course of the work. The composition of the Type 316 austenitic stainless steels studied in this investigation is given in Table I. The specimens were solution treated at 2000°F for 1/2 hr and water quenched. Those specimens subjected to prestrain at room temperature Methods for extracting precipitate particles from materials for electron and X-ray diffraction analysis have been described by Fisher,4 Smith and Nutting: and Booker and coworkers.6&apos;7 Electrolytic extraction methods have been described by Andrews and Hughes.8 The first two methods have been used at this Laboratory, but have not proved satisfactory for many problems requiring X-ray diffraction analysis. It has been difficult to remove the replicas or to avoid tearing them during removal. These difficulties are overcome by backing the replica with a water-soluble plastic such as Dupont 51-05 Elvanol (polyvinyl alcohol). The backing increases the thickness of the replica so that it can be mechanically stripped from unloosened particles without folding or tearing. This procedure eliminates the stripping of wet replicas, which usually have a low tear strength. By stripping replicas after drying, it is possible to extract partially loosened particles which otherwise would remain imbedded in the metal. The modified method is as follows: after the specimen is polished, it is etched for 60 min in modified glyceregia consisting of 30 ml glycerol, 7 ml nitric acid, and 4 ml of hydrochloric acid. The sample is then washed, air dried, and coated with a 20 pct Baker and Adamson 1611 collodion (85 pct amyl acetate by volume) film. After the collodion film is dry (about 15 min), the sample is again etched in the modified glyceregia for 50 min, washed with isopropyl alcohol (to prevent dissolving the collodion) and air dried. A very thick coat of polyvinyl alcohol (about 50 pct solution "Elvanol Dupont 51-05" in water) is poured over the sample and is permitted to dry for about 24 hr. The composite film containing the precipitates is then stripped from the specimen and floated, polyvinyl alcohol side down, in water (at about 50°C) until the polyvinyl alcohol dissolves. This usually takes about 15 min. Should any of the polyvinyl alcohol remain on the replica, it does not give a crystalline diffraction pattern and therefore does not hinder identification of the precipitates. The extraction replica, floating in water, is picked up on a glass fiber and mounted in the Debye-Scherrer camera for X-ray diffraction analysis. Concentration of the etchant, and also etching time, had to be increased for several of the samples. Fig. 1 shows two extraction replicas taken from different areas of spec. M74-37; X-ray analysis showed a strong diffraction pattern of M23C6 and a medium one of u phase. A

Jan 1, 1962

By C. T. Wei, A. Kelly

USING a recently developed X-ray method, reported by Schulz,2 it is possible to make a rapid survey of the perfection of a single crystal at a particular surface. This technique has the advantage of allowing a large surface of a specimen to be examined by taking a single photograph and it compares well with other X-ray methods in regard to sensitivity of detection of small angle boundaries. During the course of a survey of the perfection of large crystals of aluminum produced by a number of methods, an examination has been made of a number of single crystals produced from the melt using a soft mold (levigated alumina)." Crystals grown by this method are known, from an X-ray study carried out by Noggle and Koehler,3 to contain regions where they are highly perfect. In the present work, it has been possible to obtain photographs showing directly the distribution of low angle boundaries at a particular surface of these crystals. single crystals were grown from the melt using the modified Bridgman method with a speed of furnace travel of -1 mm per min. These were about 1/10 in. thick, 1 in. wide, and several inches long. The metal was 99.99 pct pure aluminum supplied by the Aluminum co. of America. The crystals were examined by placing them at an angle of about 25° to the X-ray beam issuing from a fine focus X-ray tube of the type described by Ehrenberg and Spear4 and constructed by A. Kelly at the University of Illinois. A photographic film was placed SO as to record the X-ray reflection from the lattice planes most nearly parallel to the crystal surface. The size of the focal spot on the X-ray tube was between 25 and 40 u, and the distance from the X-ray tube focus to the specimen (approximately equal to the specimen to film distance) was -15 cm. White X-radiation was used from a tungsten target with not more than 35 kv in order to reduce the penetration of the X-rays into the specimen. Exposure times were approximately 1 hr with tube currents between 150 and 250 microamp. The type of photograph obtained from these crystals is illustrated in Fig. 1, which shows a number of overlapping reflections from the same crystal. The large uniform central reflection is traversed by sets of horizontal white and dark lines. These two sets run mainly parallel to one another. Lines of one color are wavy in nature and often branch and run together. Large areas of the crystal surface show no evidence of these lines whatsoever. The lines are interpreted as being due to low angle boundaries in the crystal, separating regions which are tilted with respect to one another. A white line is formed when the relative tilt forms a ridge at the interface and a black line is found when a valley is formed. In a number of cases, the lines stop and start within the area of the reflection and often run into the reflection from the edge, corresponding to a low angle boundary starting from the edge of the crystal. The prominent lines run roughly parallel to the direction of growth of the crystal although narrow bands can run in a direction perpendicular to this; see Fig. 2. Although they may change their appearance slightly, the lines tend to occur in the slightly,Same place in the X-ray image and to maintain their rough parallelism when the crystals are reduced in thickness by etching. Thus the low angle boundaries can occur at any depth within the crystal. The appearance of the lines is unaffected by subjecting the crystal to rapid temperature changes, such as plunging into liquid nitrogen or rapid quenching from 620°C. From the width of the lines on the x-ray reflection, values can be found for the angular misorienta-tion of the two parts of the crystal on either side of a boundary. The values found run from 1&apos; to 10&apos; of arc, but values of UP to 20&apos; have sometimes been found, e.g., the widest lines on Fig. 2. These mis-orientations are much less than those commonly found in crystals possessing a lineage structure. When a number of a and white lines occur, running in a roughly parallel direction across the image of a Crystal, the total misorientation corresponding to lines of one color is approximately equal to that corresponding to lines of the other color. The interpretation of the lines as due to low angle boundaries has been checked in a number of ways. Photographs taken with different specimen-to-film distances distinguish lines due to low angle boundaries from effects due to surface relief of the specimen. Normal Laue back-reflection photographs, taken with the beam irradiating an area of the surface showing a number of the lines, show white lines running through each Laue spot. Black lines are set to see by this method. X-ray photographs were also taken, using the set-up described by Lam-one et al.5 when the beam straddles regions giving rise to lines in the Schulz pattern, split reflections are observed within the Bragg spot. The misorienta-tions calculated from the separation of these reflections and that found from the widths of the lines on the schulz technique patterns show good agreement. An exposure was made with Lambot technique of an area of the crystal showing no evidence of low angle

Jan 1, 1956

PRESIDENT. CHARLES F. RAND,1 NEW YORK, N. Y. PAST PRESIDENTS. CHARLES KIRCHHOFF,1 NEW YORK, N. Y. JAMES F. KEMP,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT. BENJAMIN B. THAY ER,1 NEW YORK, N. Y. TREASURER. GEORGE C. STONE,1 NEW YORK, N. Y.

Jan 4, 1913

Institute of Metals Division PAUL D MERICA, Chairman ZAY JEFFRIES, Vice-chairman W M CORSE. Secretary General Committee ROBERT J ANDERSON H C JENNISON L W SPRING WILLIAM K FRANK DAVID LEVINGER R L SUHL J R FREEMAN, JR. PAUL McKINNEY R F WOOD STANISLAUS SKOWRONSKI

Jan 1, 1923

Established as a Division March 24, 1922 John R McMillan, &apos;56, Chairman Claude R Hocott, &apos;55, Past Chairman Thomas C Frick, &apos;56, Vice-Chairman D W Akins, &apos;57, Vice-Chairman Joe B Alford, Executive Secretary 800 Fidelity Union Building Dallas 1, Texas T A Pollard, Treasurer

Jan 1, 1954

UNITED ENGINEERING TRUSTEES, INC James L Head, &apos;51 E C Meagher, &apos;52 Gail F Moulton, &apos;53 ADVISORY COMMITTEE TO REAL ESTATE COMMITTEE Cleveland Dodge Herbert Hoover Paul D Merica HOOVER MEDAL BOARD OF AWARD Scott Turner, &apos;56, Chairman Cadwallader Evans, Jr , &apos;52 Paul D Merica, &apos;54

Jan 1, 1951

By G. D. Gemmell

Effects of solid-sdutidn alloying with titanium, molybdenum, and tungsten at concentrations up to 10 pct on the strength of pure columbium at elevated temperatures (mainly 2000°F) have been investigated by means of creep-rupture, hot-tensile, and hot-hardness testing and recrystallization studies. ThIS paper presents some results from the initial part of a study of the effects of alloying on the high-temperature strength properties of columbium. The elevated-temperature strength characteristics of pure columbium were first studied. Binary alloys of columbium with titanium, molybdenum, and tungsten containing 1, 5, and 10 pct of the solute elements were chosen on the basis of their high melting points, their known solid solubility in columbium, and results of separate oxidation-resistance studies of columbium alloys. EXPERIMENTAL PROCEDURE All the materials used were of highest purity. A typical analysis of the columbium is shown in Table I. Compositions of the alloys are also given in Table I. To evaluate the strength properties of pure co-lumbium and the alloys at elevated temperatures, creep-rupture, hot-tensile, and hot-hardness testing was done on recrystallized material. To prepare the pure metal and the alloys for these tests, 1- 1b buttons were made in a water-cooled copper crucible, inert atmosphere, tungsten arc furnace. Tapered ingots, 3 in. long, were made from these buttons by a skull-casting technique and these were machined to 1/2 in. diam, swaged to 50 pct reduction (pure columbium at room temperature, alloys at lowest temperature possible without cracking, generally in range 1100" to 1800°F) and heated in vacuum (lo-&apos; mm Hg) for 16 hr at 2550°F for re-crystallization and homogenization. The resulting grain diameter was 0.1 to 0.3 mm. The 10 pct Mo alloy casting was not successfully swaged at temperatures up to 1800°F without cracking and was not included in the test program. Creep-rupture testing was done at constant load in vacuum on cylindrical specimens of 0.16 in. diam, using Instron capsules. The pressure at test temperatures was less than 10-1 mm Hg. Hardneas readings taken on the test specimen before and after testing were used as a check on possible gaseous contamination. Hot tensile tests in vacuum on cylindrical specimens of 0.125 in. diam were also made with Instron equipment at a strain rate of 0.067 min.-l. Hot-hardness measurements were taken with a unit constructed at the Du Pont Experimental Station. The test piece, supported on an alumina anvil, and the molybdenum indenter shaft with sapphire tip is heated in a platinum-wound furnace. The load applied to the pyramid indenter is measured by strain gages attached to a proving ring located outside the hot zone. In the measurements reported here the load was I kg. The tester operates in a vacuum of about 10"5 mm Hg and is capable of temperatures up to 1400°C.

Jan 1, 1960

By C. Dean Starr

The physical basis of the equation correlating electrical conductizlity and temperature coefficient of resistance of solid solution alloys has been inzlestzgated and the nature of the constants evaluated. It is shaun that the same form of correlation is valid irrespective of the magnitude of the temperature coefficient. However, the effect of therma1 expansion and change in resistivity with temberature nust be considered when the magnitude of the temperature coefficient of resistance is near zero. In a comprehensive literature survey conducted at the Armour Research Foundation in 1950, it was found that a linear relationship exists between the electrical conductivity, K, and the temperature coefficient of resistance, a, for solid solution alloys. This was expressed by the equation where B, a constant, depends on the solvent metal but not the solute. A continuing investigation by Hansen, Johnston, and Parks showed this equation was generally appropriate for Cu, Ag, Au, Pd, Pt, and Co base binary solid solution alloys as well as for many ternary alloys of copper over a range of conductivities and temperature coefficient of resistances from 0.02 to 0.60 reciprocal pohm cm and-0.00015to0.004Q per 0 per "C respectively. Eq. [I] was not always valid for alloys that exhibited a change in state (magnetic to nonmagnetic) or for alloys that had a temperature coefficient of resistance near or below zero. For example, in nickel alloys, a simple linear curve as predicted by Eq. [l] was not obtained when the conductivity was plotted against the temperature coefficient of resistance. Hansen suggested that deviations observed were caused by transitions from a ferromagnetic to a nonmagnetic state. Subsequent and more extensive data by ronin on Ni-Mn alloys confirmed Hansen&apos;s postulate. While both states independently showed a linear relationship between K and a, the value of B was different for the two states. In some copper and gold base alloys, as well as the platinum and palladium alloys investigated by Hansen, the conductivity did not extrapolate to zero at zero a as demanded by Eq. [I]. This deviation can be readily corrected by simply adding a constant to Eq. [I.] whence Eq. [2] shows the K decreases as a decreases but that K has a positive value when a = 0 which is observed for commercial solid solution alloys as well as the experimental alloys tested by Hansen. While other methods of correlation of electrical properties have been made such as the one by Starr and Wang3 who found a linear relationship between resistivity and temperature coefficient of resistance for Ni-Cr-Al-Cu alloys, the data, in general, can also be correlated by a form of Eq. [2]. Thus, Hansen&apos;s empirical equation has considerable merit. The objective of this paper is to determine the physical basis for this equation and to examine the region near zero a in more detail. ELECTRICAL CONDUCTIVITY VS TEMPERATURE COEFFICIENT OF FU3SISTANCE The resistance of a metal or alloy is defined as

Jan 1, 1963