Reply to comments of D. H. Zeuch
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inhomogeneity caused by frictional forces as specimen shortening becomes extreme; effects of friction and sample length can be explored parametrically.13 Unlike brittle materials, superimposed hydrostatic pressures have little effect on the mechanical properties of ductile metals except as high pressures affect creep rates through separation of partial dislocations or the activation volume for diffusion.4 However, although intermetallic alloys exhibit far greater ductility than classically brittle materials, they nevertheless fail by fracturing and are therefore almost certainly pressuresensitive. It would be of fundamental interest to explore the extent of pressure-sensitivity of intermetallic alloys by conducting triaxial compression experiments of the sort discussed above, as these materials appear to be transitional in behavior between classically brittle and fully ductile materials. Furthermore, results of such a study could have practical applications. Hydrostatic pressures have already been used at high homologous temperatures to suppress creep cavitation (void coalescence) in metals and ceramics, with the goal of developing new fabrication techniques. 1415 Hydrostatic pressures could, perhaps, also be used to suppress fracture and promote plastic deformation by intracrystalline slip in intermetallic alloys at low temperatures, to form rough or fully finished parts.
2. M. Yamaguchi, Y. Umakoshi, and T. Yamane, Philos. Mag. 55A, 301 (1987). 3. C. D. Turner, W. O. Powers, and J. A. Wert, Acta Metall. 37, 2635 (1989). 4. M.S. Paterson, Experimental Rock Deformation: the Brittle Field (Springer-Verlag, New York, 1978), 254 pp. 5. 1990 Annual Book of ASTM Standards (American Society for Testing of Materials, Philadelphia, 1990), Vol. 0 4 - 0 8 , p. 360. 6. 1990 Annual Book of ASTM Standards (American Society for Testing of Materials, Philadelphia, 1990), Vol. 0 3 - 0 1 , p. 161. 7. B. Evans, J. T. Fredrich, and T-F. Wong, in The Brittle-Ductile Transition in Rocks, edited by A. G. Duba, W. B. Durham, J. W. Handin, and H. F. Wang (The American Geophysical Union, Washington, DC, 1990), p. 1. 8. P. G. Meredith, in Deformation Processes in Minerals, Ceramics and Rocks, edited by D. J. Barber and P. G. Meredith (Unwin Hyman, Boston, 1990), p. 5. 9. S. D. Peng, Int. J. Rock Mech. Min. Sci. 8, 399 (1971). 10. S.D. Peng and A.M. Johnson, Int. J. Rock Mech. Min. Sci. 9, 37 (1972). 11. A.M. Starfield and W. R. Wawersik, in Basic and Applied Rock Mechanics: Proceedings of the Tenth U.S. Symposium on Rock Mechanics (Society of Mining Engineers of the AIME, 1972), p. 793. 12. J. C. Jaeger and N. G. W. Cook, Fundamentals of Rock Mechanics (Chapman and Hall, London, 1976), 585 pp. 13. L. J. Branstetter and D. S. Preece, in Rock Mechanics, TheoryExperiment-Practice: Proceedings of the Twenty-Fourth U.S. Symposium on Rock Mechanics (Association of Engineering Geologists, Short Hills, NJ, 1983), p. 37. 14. J-G. Wang and R. Raj, J. Am. Ceram. Soc. 67, 399 (1984). 15. C. C. Bampton and R. Raj, Acta Metall. 30, 2043 (1982).
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