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EXECUTIVE COMMITTEES OF LOCAL SECTIONS New York L. W, FRANCIS, Chairman, WILLARD S. MORSE, Vice-Chairman. THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y. P. A. MOSMAN, Treasurer. LOUIS D. HUNTOON. Boston HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. TIMOTHY W. SPRAGUE, HENRY A. WENTWORTH. Columbia F. A. THOMSON, Chairman. GEORGE W..RODDEWIG, Vice-Chairman. LYNDON K, ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. R. S. McCAFFERY, S. H. RICHARDSON.

Jan 7, 1914

EXECUTIVE COMMITTEES OF LOCAL SECTIONS New York L. W. FRANCIS, Chairman, WILLARD S. MORSE, Vice-Chairman. THOMAS T. READ, Secretary, Woolworth Bldg., New York. N. Y. P. A. MOSMAN, Treasurer. LOUIS D. HUNTOON. Boston HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. TIMOTHY W. SPRAGUE, HENRY A. WENTWORTH. Columbia F. A. THOMSON, Chairman. GEORGE W. RODDEWIG, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. 0. Drawer 2154, Spokane, Wash. R. S. McCAFFERY, S. H. RICHARDSON.

Jan 9, 1914

EXECUTIVE COMMITTEES OF LOCAL SECTIONS New York L. W. FRANCIS, Chairman, WILLARD S. MORSE, Vice-Chairman. THOMAS -T. READ, Secretary, Woolworth Bldg., New York: N. Y. P. A. MOSMAN, Treasurer. LOUIS D: HUNTOON. Boston HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. TIMOTHY W. SPRAGUE, HENRY A. WENTWORTH. Columbia F. A. THOMSON, Chairman. GEORGE W. RODDEWIG, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. R. S. McCAFFERY, S. H. RICHARDSON.

Jan 10, 1914

EXECUTIVE COMMITTEES OF LOCAL SECTIONS New York L. W. FRANCIS, Chairman. WILLARD S. MORSE, Vice-Chairman. . THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y. P. A. MOSMAN, Treasurer. LOUIS D. HUNTOON, Boston HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. TIMOTHY W. SPRAGUE, HENRY A. WENTWORTH. Columbia F. A. THOMSON, Chairman. GEORGE W. RODDEWIG, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. R. S. McCAFFERY, S. H. RICHARDSON.

Jan 6, 1914

EXECUTIVE COMMITTEES OF LOCAL SECTIONS New York L. W. FRANCIS, Chairman, WILLARD S. MORSE,. Vice-Chairman. THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y. P. A. MOSMAN, Treasurer. LOUIS D. HUNTOON. Boston HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman. AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. TIMOTHY W. SPRAGUE, HENRY A. WENTWORTH. Columbia F. A. THOMSON, Chairman. GEORGE W. RODDEWIG, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. R. S. McCAFFERY, S. H. RICHARDSON.

Jan 8, 1914

By W. F. Rochow, W. C. Burke

Numerous designs of linings and accessories, including dams, lifters, and heat exchangers, contribute greatly to kiln efficiencies. Greater conductivity is achieved with basic brick than with fireclay and high-alumina refractories, depending largely upon the use of steel plates in radial joints between adjacent brick to increase heat transfer through the lining. Refractory lifters expose all portions of the load to radiant or convective heat and raise some portions to higher temperatures by cascading the load down through the path of the hot gases.

Jan 3, 1955

By A. E. Gorum, I. Cornet

Fatigrle of ionic crystals has been studied primarily in magnesinm oxide. under cyclic stress dislocations move irrreversibly; they multiply; slip bands form and grow; cracks mucleate and propagnte, and failure occurs. The use of ionic crystals such as MgO is advantageorus in such investigations because they are optically transparent. Individual dislocation Intersections with {100} surfaces may be observed with a standard microscope, using etch-pit techniques. Slip, deformation, crack .formation, and fracture in MgO crystals under cyclic stress are compared with cotrresponditzg processes in metals. ThE effect of cyclic loading in metals has been studied for many years. The appearance of slip lines is readily observed and the ensuing fracture may also be seen. From these observations it is possible to predict the behavior of a material and make an educated guess as to what is happening internally, but the actual changes taking place within the structure are not readily apparent. If one could obtain a material in which the individual glide components could be observed, it would be invaluable in determining the actual slip distribution resulting from cyclic loading as well as the distribution of slip in the neighborhood of a growing crack. Such a material is magnesium oxide. Dislocation arrays may be observed by means of etch pits

Jan 1, 1961

By T. D. McKinley

Theory, operational characteristics, and indicated precision and accuracy of analytical methods based on vacuum extraction, equilibrium pressure, and combustion approaches are reviewed. At the present time vacuum extraction at 1400°C and the equilibrium pressure method are recommended for determination of hydrogen in titanium and titanium-rich alloys. UNTIL a few years ago the role of hydrogen in titanium was an unknown factor with regard to its effect on the physical and mechanical properties of the metal. However, following the work of Jaffee and othersa-" it is now generally acknowledged that hydrogen has a degrading effect on titanium and its alloys. The chief manifestations are a decrease in impact strength in -systems and delayed cracking in a-ß systems. Since hydrogen does have a de- grading effect on titanium it is essential to control it within tolerable limits. It then follows that procedures for quantitative estimation of hydrogen are a primary requirement for the industry. For greatest benefit these methods should be simple, rapid, and precise. In addition to having these virtues, methods must be easy to duplicate in both equipment and technique to gain widespread use. After inherent accuracy has been established, the, required precision to make a method acceptable is dependent largely on the nature of the work at hand. Ability to obtain a representative sample has a pro-

Jan 1, 1959

By F. A. Crossley

The key to disagreements between Blackburn's findings and mine is the word equilibrium". My work attempted to define the equilibrium diagram of the titanium-rich end of the Ti-A1 system. It can readily be shown that Blackburn's conclusions are based primarily on the examination of structures substantially removed from equilibrium. The diagram presented in Fig. 16 is properly labeled a "phase diagram". However, it appears that Blackburn either does not understand or does not accept the difference between "phase diagram" and "equilibrium diagram" as defined in the Metals Handbook.17 The conflict lies not in Blackburn's data but in his interpretation of it, and his use of "transformation", "phase diagram", and "equilibrium diagram" as synonymous terms. I share his view that the light microscope is much inferior to the transmission electron microscope for the study of transformations; but this fact does not render the light microscope useless or untrustworthy. The difficulties experienced with the Ti-A1 system have not been due to the limitations of the light microscope, but rather to the extreme sluggishness in achieving equilibrium at temperatures below 1000° C. Were it not for the light microscope employed with polarized light, the twin phase syndrome' might still be unrecognized and, as a consequence, still adding to the confusion of Ti-A1 investigations. (Ref. 1 should read ... Contract No. N161-25952 ... vol. 236.) Other, more sophisticated techniques, including electron transmission, simply confirm the erroneous tentative conclusions drawn from observations of structures due to the twin-phase syndrome. By the standards of most of the investigations of the Ti-A1 systems, seven of the fifteen compositions investigated by Blackburn were seriously contaminated with oxygen. The writer has found that 0.1 wt pct 0 shifts the a + Ti3A1 boundary to 1 at. pct lower A1 content at 700°C. At constant aluminum content, this corresponds to a temperature shift of the boundary of +25°c.18 Blackburn advises that the first group of alloys contained 0.1 to 0.15 wt pct 0, bur he does say whether the analyses were performed on as-received material or on specimens in their final state of heat treatment. This is especially important considering the 20-mil-thick starting materials. If specimens had been annealed in the two-phase a + 6 region it would have provided an indication of the final degree of oxygen contamination since up to about 12 at. pct A1 the boundaries of this region are well-defined for low-oxygen alloys. Blackburn questions the capability of light microscopy in determining phase boundaries in the Ti-A1 system. I submit that the a/a + Ti3A1 boundary in Fig. 1 of Ref. 1 over the composition range from 10 to 18 at. pct A1 was determined by dilatometry and supported by electron diffraction. Specimens of alloys containing 8, 10, 12, and 14 at. pct A1 were aged at 550°C for 1000 hr (under stress of 5000 psi to accelerate the tendency to equilibrium) and then fractured in tension at room temperature. Collodion was applied to the as-fractured (unetched) surface and, when stripped, carried away particles identified by electron diffraction as Ti3A1. Perhaps Blackburn will explain why these electron diffraction data were ignored. At this time, a technique for revealing or indicating

Jan 1, 1969

By A. Vignes, J. P. Sabatier

A study of ternary diffusion at 1315°C in the Fe-Co-Ni system covering the entire ternary phase diagram has been carried out. Experimental values of the four interdiffusion coefficients DFeNico,DFeCoCo, DFeCoNi were computed at 33 points of the ternary diagram. The limiting values of these coefficients on the three sides of the ternary diizgram have also been determined. This set of data is presented as a contour map on the ternary isotherm for each of the four coefficients. Assuming that the Fe-Co-Ni system can be considered as ideal, the phenomenological coefficients Lk ij (with k = Fe) have been computed and the Onsager reciprocal relutions verified. It is shown that, in the Fe-Co-Ni system, the diffusion process can also be described by only two interdiffusion coefficients DFeFe and DCoNiFe, the second cross diffusion coefficient DCoFeNi being equal to zero and the second direct difusion coefficient being given by The values of the cross interdiffusion coefficients and of the Onsager coefficients are explained in terms of atomic mobilities of the three components with the help of a kinetic calculation due to Lane and Kirkaldy.8 It is shown that all the results are explained if the tracer difusion coefficients of the three components are such that DFe > DNi ~ DCo in complete agreement with experimental data on the three binary systems. DIFFUSION in a ternary alloy system is basically and significantly different from diffusion in binary alloys. In binary diffusion, there is just one independent composition variable and only one coefficient Dij is needed to describe the interdiffusion process. In ternary diffusion, we must allow for cross interaction between two independent species, and four interdiffusion coefficients are necessary to describe the transport process. Kirkaldy et al.1,2 have determined interdiffusion coefficients in the systems, Cu-Mn-A1 and Zn-Cu-Al. Guy and Leroy4 have reported intrinsic diffusion coefficients for the r phase at 1300°C of Co-Ni-Cr alloys as a function of composition using the analysis of Philibert and Guy.3 Interdiffusion coefficients were measured at three different compositions at 850°C in the single phase copper-rich corner of the Cu-Zn-Mn system by Dayananda and race.5 Zie-bold and Ogilvie6 have determined interdiffusion coefficients in the single-phase field of the Cu-Ag-Au system at 725°C. Preliminary results on diffusion at 1136°C in the system Fe-Co-Ni have been reported.7 In this study, data are reported on a more complete determination of interdiffusion coefficients in the Fe-Co-Ni system in the entire ternary at 1315°C. There is complete solid solubility with the fcc structures at 1315ºC, and this system can be considered as nearly ideal. This approximation allows the computation of the Onsager phenomenological coefficients. These values can then be used to test a kinetic calculation of the Onsager L coefficients in ternary substitutional solid solutions due to Lane and Kirkaldy.8

Jan 1, 1970

By ELLSIVOKTH DAGGETT

THE Berlin gold quartz mine is situated in Nye county, Nevada, on the west flank of the Shoshone range, about 40 miles south and 30 miles west from the town of Austin, the county-seat of Lander county. The distance from Austin is about 60 miles by stage-road. The outcrop of the vein, at the top of the incline-shaft, is situated just at the base of the mountain proper, almost exactly at the intersection of the mountain-side with the gravelly bench that slopes for about three-quarters of a mile to the flatter sage-brush plain, or desert valley, below. The -vein itself consists almost entirely of quartz, with perhaps 2 per cent. of sulphide of iron, copper, lead, zinc and antimony, and perhaps a trace of some of the compounds of tellurium with gold and silver, although none of the latter have been as yet positively identified. The relative proportion, by weight, of silver and gold in the ores, varies in different parts of the vein, from 12 silver for 1 of gold, to 7 silver for 1 of gold. The quartz vein-filling is usually frozen fast to the walls, and is very hard and compact, seldom showing the friable, fissured, or shelly structure often to be found in quartz veins. Comparatively little evidence of relative motion of one wall of the vein upon the other is to be found-a fact indicating that during the formation of the vein, and prior to the extensive movements herein described, little disturbance had taken place. No evidence whatever of metasomatic origin has been observed. On the other hand, occasional occurrences of comby structure, in which the axes of the quartz crystals are at right angles to the plane of the vein, rather indicate deposition from solution in a pre-existing fissure. Spurs, or branches, and small parallel veins, while not en-\

Mar 1, 1907

By William L. Saunders

Many members of the Institute, who participated in the visit made, during the Bethlehem meeting of February, 1906, to the shops of the Ingersoll-Rand Company, at Phillipsburg, N. J., inspected with interest the new Electric-Air drill, which the company had set up for the purpose of showing it in actual operation to American mining engineers. At the request of the Secretary of the Institute, I promised at that time to prepare a paper for our Transactions, describing the construction and advantages of the machine. But such a paper would then necessarily have contained much that was only expected or claimed by the designers and manufacturers of the drill, and not yet incontrovertibly proved by varied and long-continued practice. However moderate such statements might have been, they would have given inevitably to the paper, to some extent at least, the air of a prospectus, rather than of a technical contribution. I therefore decided, with the Secretary's approval, to postpone the writing of the promised paper until it could set forth the results of adequate actual practice, as well as the latest details of construction, etc., based upon practical experience. That period has now arrived. The Electric-Air drill has been exhaustively tested in the field, under varied and arduous conditions and upon the hardest rocks. It is now fairly in the field; its merits and performances are matters of unimpeachable record, and its place among established competitors can be definitely determined. As a representative of the Ingersoll-Rand Co., as well as a member of the Institute, I may be permitted to add that my company, being largely interested in the manufacture of air-coxpressors and machinery driven by compressed air, has no desire to injure its own business by claiming for this new machine that it should immediately supersede all existing applications of pneumatic transmission of power for drilling. On the

Jan 1, 1908

By W. D. Robertson, Raymond C. Boettner

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

Jan 1, 1962

The war story of the engineer corps at home and in France is told officially for the first time in the advance sheets of the War Department's brief history of American war efforts. Many of these accomplishments have been published before as isolated incidents, but they gave no idea of the extraordinary duties modern warfare has laid upon engineering troops. In the engineering units that reached the other side, there were seven regiments and two battalions of railway construction engineers; five battalions for maintenance of way; two battalions for maintenance of railway equipment; four regiments and one battalion to operate the main American railways in France; three regiments to operate light railways and their repair shops; two regiments to operate the regular railway repair shops; two regiments and six separate battalions on general construction work; two regiments for storing and transporting engineer supplies; a forestry regiment; a light-railway construction regiment; a roadbuilding regiment; a water-supply regiment; a mining regiment; a quarrying regiment; a technical regiment for surveying and sound ranging; three survey and printing battalions; two railway transportation battalions; an electrical and mechanical regiment; several separate companies to operate cranes; a camouflage service; five inland waterway companies, to operate canal boats and the like; five pontoon trains and a pontoon

Jan 6, 1919

By Walter Kauzmann

ALL viscous or plastic flow of incompressible matter is the result of shear strain; the changing shape of any body that is being plastically deformed can be completely described in terms of the shear strain occurring at each point in the body.[t] Furthermore, the relative amounts of shear strain occurring in different parts of a body under stress depend upon the relative rates of shear strain at those different points, so that if the dependence of the shear rate of any material on the temperature, shear stress, previous history, etc., were understood, the principles of plastic deformation would be known, and we could calculate how a body made of a given material, having a given shape, and subject to a specified system of forces, would change its shape with time. It may be said, then, that the problem of plasticity resolves itself into, first, the problem of the rates of pure shear processes, and second, the application of what is known about pure shear to actual cases. It is the purpose of this work to investigate the former problem -i.e., the dependence of shear rates on temperature, stress, etc.-from the standpoint of recent developments in the field of chemical-rate theory and with particular reference to the phenomena occurring in the creep of metals and in the plastic flow of crystalline solids in general. It is left for the mechanical engineer, and perhaps the expert in hydrodynamics, to deal with the problem of applications1 RESOLUTION OF MACROSCOPIC SHEAR INTO MICROSCOPIC MOVEMENTS; RESEMBLANCE TO CHEMICAL REACTIONS Just as any large body is made up of many small units, or atoms, so macroscopically observable shear is the result of many microscopic unit shear processes; just as the understanding of the behavior of large bodies demands the understanding of the atoms of which it is made, so the understanding of macroscopic shear demands the understanding of these fundamental unit processes. The study of shear from this "atomistic" point of view has made considerable progress. There has been fairly complete understanding of shear processes in gases for a long time, at least for nonturbulent flow, as a chapter on gaseous viscosity in any text on the kinetic theory of gases will prove. In recent years Andrade2 and Eyring3 have presented important theories for the flow of liquids and amorphous solids. Becker,4 Orowan,5 Taylor,6 Burgers,7 and Kanter8 have considered the

Jan 1, 1941

By V. Lessels, D. J. Buckwalter, D. H. Rose

At White Pine Copper Co.'s operation in the Upper Peninsula of Michigan, the company has been losing more than four lbs of copper in each ton of sand tailings. With an average rate of 12,000 tpd of sand going to the tailing pond daily, the company has been losing more than 14 million lbs of the red metal annually. With an eye aimed toward lessening this loss, White Pine engineers in 1959 initiated a study on techniques for recovering this "lost" copper from the sands. Inasmuch as the flotation operation was considered to be optimized, a logical approach seemed to be leaching. For various reasons ammonia, ferric chloride, acid, and biological leaching were ruled out as impracticable. This led to a consideration of cyanide leaching as practiced in the precious metals industry.

Jan 8, 1967

In 1970, the federal Clean Air Act was passed, promulgating limits on the emissions of sulfur dioxide (SO2) from large stationary sources that would affect local air quality. The brunt of this regulation was felt by the electric utility industry, especially those units generating electricity with coal-fired boilers. The law hastened development of a new industry, flue gas desulfurization (FGD), which is composed of three major segments: the electric utility, the FGD equipment suppliers (the scrubbing modules), and the scrubbing chemical suppliers. Dravo's experience suggested the equipment end of the business, but market analysis recommended investigating the chemical processes involved in the removal of the SO2 gas. This resulted in the formation of Dravo Lime Co. to manufacture and market reagents to the FGD industry. This paper will briefly describe the Thiosorbic lime scrubbing process and review Dravo's innovative mine and calcining facility.

Jan 1, 1982

By Lester Tarnopol, Ralph Hultgren

A considerable interest in the subject of superlattices has been manifested by many papers and reviews that have recently appeared, both in physical and metallurgical publications. This interest is due largely to the apparent simplicity of the ordering process, which permits the explanation of many phenomena on the basis of elementary theory. Moreover, ordering may cause important changes in the physical properties of alloys. In this paper, we shall discuss the causes of superlattices in terms of simple properties of the elements that give rise to them, together with a series of experiments performed to test our conclusions. Evidence is presented that in some cases the process of ordering is more complex than might be supposed. While the different species of atoms are usually found in random positions in alloy lattices, in some cases unlike atoms tend to be nearest neighbors. Bethe's1 "order of neighbors" is a statistical measure of thib tendency. At suitable compositions it is possible for atoms in large regions to be regularly arranged, which causes superlattice lines to appear. in X-ray diffraction patterns. Bragg and Williams2 haw dealt with this "long-distance order" in their fundamental work 011 superlattices. Excellent discussions of superlattices are to be found in current reviews TheRmodynamic Considerations Thcrmal vibration tends to destroy order. The magnitude of the effect can be determined from the entropy of mixing, which is calculate from first principles. Since the ordered state has the lower entropy, it must also have a lower internal energy to be stable at any temperature. The difference in internal energy determines the critical temperature at which long-distance order disappears. According to the, theory of Bragg and Williams,~

Jan 1, 1939

By Lester Tarnopol, Ralph Hultgren

A considerable interest in the subject of superlattices has been manifested by many papers and reviews that have recently appeared, both in physical and metallurgical publications. This interest is due largely to the apparent simplicity of the ordering process, which permits the explanation of many phenomena on the basis of elementary theory. Moreover, ordering may cause important changes in the physical properties of alloys. In this paper, we shall discuss the causes of superlattices in terms of simple properties of the elements that give rise to them, together with a series of experiments performed to test our conclusions. Evidence is presented that in some cases the process of ordering is more complex than might be supposed. While the different species of atoms are usually found in random positions in alloy lattices, in some cases unlike atoms tend to be nearest neighbors. Bethe's1 "order of neighbors" is a statistical measure of thib tendency. At suitable compositions it is possible for atoms in large regions to be regularly arranged, which causes superlattice lines to appear. in X-ray diffraction patterns. Bragg and Williams2 haw dealt with this "long-distance order" in their fundamental work 011 superlattices. Excellent discussions of superlattices are to be found in current reviews TheRmodynamic Considerations Thcrmal vibration tends to destroy order. The magnitude of the effect can be determined from the entropy of mixing, which is calculate from first principles. Since the ordered state has the lower entropy, it must also have a lower internal energy to be stable at any temperature. The difference in internal energy determines the critical temperature at which long-distance order disappears. According to the, theory of Bragg and Williams,~

Jan 1, 1939

By W. A. Backofen, D. Lee

Tlze condition of superplasticity or neck-resistanl flow that results front high strain-rate sensitivity has been observed in isothermal tension tests on several titanium alloys and one of zirconium hi general, il was associated with reasonably fine-grain micro-structures being stvained in the transformation range at rates below i - 10 -3 sec-&apos;. The metallographic mean-free path, L, was measured at room temperature after rapid cooling from the temperature of test-ing. The flow stress of Ti-GAL-4V at 950°C was proportional to La at different constanl <; the value of a decreased with increasing. E but at E< 1.5 x 10-4 sec-1 it varied only from 0.9 to 1.25. The findings were interpreted to mean that viscous boundary shear is the rate-controlling process of deformation at high levels of strain rate sensitivity in these materials. Elongation of over 1000 pet could be obtained, but a1 temperatures so high and rates so low that any practical application of the full effect would probably be difficult. As the transformation range was narrowed, by turning from Ti-6AL-4V to Ti-5Al-2.5sn to nomznally pure titanium, the allowable temperature varialion was correspondingly reduced. Superplasticily was not found in Armco iron, presumably because the transformation range was too narrow to allow the developtnenl of a reasonably stable microstructure for isolhermal lesting. THE work represented by this paper grew out of a recent study of texture hardening in a(hcp) titanium and zirconium-alloy sheet,&apos; of which part has now been published.2 It was found that, with heating, the tensile plastic-anisotropy index, R,* was decreased from well above 1 towards 1 as the temperature range for the a(hcp) -ß(bcc) phase change was entered. The clearest example of that trend is illustrated with previously unpublished data in Fig. 1. It might have been thought that such a development resulted simply from introduction of the cubic and therefore plastically less anisotropic phase. However, the accompanying change in the index of tensile strain-rate sensitivity, m = a log a/a log E, was rapidly upwards, to a high of 0.85 in some cases (also illustrated in Fig. 1). At the same time, the total tensile elongation rose to a maximum and the flow strength dropped away as R (and m) approached 1. Taken together, the observations cannot be understood as resulting from the presence of cubic phase, per se. It has been concluded instead that they reflect the largely noncrystallographic deformation which characterizes superplasticity. As demonstrated in other recent work? a necessary condition for super-plasticity is strain-rate sensitivity of flow stress sufficiently high that m is above a lower limit of -0.3. The origin of large m has been traced, in turn, to grain size so small that a substantial amount of viscous deformation is introduced by such processes as Nabarro-Herring diffusional flow4 and/or grain boundary shear.5,6 Because of problems in the processing of titanium and zirconium alloys—problems of high strength, limited ductility, and excessive springback, originating largely in slip resistance-it was natural to wonder if something useful might be done with superplasticity in those materials. Therefore experiments were made for more closely identifying and generally bounding the phenomenon with temperature and strain-rate limits, before attempting to decide about its exploitation. The results are being reported here. EXPERIMENTAL Materials. The two of primary interest were the titanium alloys of nominal composition (in wt pct) 5A1-2.5Sn and 6A1-4V. Others were a 4A1-1/4O2 titanium alloy, titanium of commercial purity (RC-70), Zircaloy-4. and Armco iron. All were received as annealed 3/16 in. thick sheet, except RC-70 which was & in. thick, and tested in that condition. Details of transformation temperature and grain size are given in Table I. The results of dilatometry for the measurement of transformation temperatures were unsatisfactory. Data were finally obtained by metallographic examination of each specimen after test, to determine from the amount of transformed 4 where the specimen had been heated in relation to the critical temperatures. Results were in reasonable agreement with information from the supplier. Strip tensile specimens were of full sheet thickness and taken along the rolling direction, except for those

Jan 1, 1968