Abstract
Resolved yield stresses were determined in tension and compression for ultra high vacuum degassed tantalum crystals as a function of orientation at 77 K and 197 K. The yield stress at 77K was a minimum for specimens oriented to slip on the (112) [111] system, and a maxi-mum for specimens oriented to slip on the (–112) [1–11] system. The yield stress in tension was less than the yield stress in compression for all orientations. However, at 197 K, the yield stress in tension was found to be greater than in compression for specimens oriented to slip on the (121) [111] system in agreement with the results of Lachenmann and Schultz,1 who also found that, for specimens oriented to slip on the (•112) [1–11] system, the yield stress in compression was higher than the yield stress in tension, as occurs at 77 K. This behavior may be explained by the influence of a normal stress on a lattice expansion which occurs when the leading 112 stacking fault of a dissociated core dislocation as described by Dues-beryet al2 begins to move.
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R. Lachenmann and H. Schultz:ScriptaMet., 1972, vol. 6, pp. 731–36.
M. S. Duesbery, V. Vitek, and D. K. Bowen:Proc. Roy. Soc. London, 1973, vol. A332, pp. 85–111. See also various papers inInteratomic Potentials and Simulation of Lattice Defects, Plenum Press, New York, 1972.
J. W. Christian:Second Int. Conf. on the Strength of Metals and Alloys, p. 3, American Society for Metals, 1970.
P. B. Hirsch:Trans. Jap. Inst. Metals, 1968, Suppl. to vol. 9, pp. 30–39.
K. V. Ravi and R. Gibala:Second Int. Conf. on the Strength of Metals and Alloys, p. 83, American Society for Metals, 1970.
P. J. Sherwood, F. Guiu, H. C. Kim, and P. L. Pratt:Can. J. Phys., 1967, vol. 45, pp. 1075–89.
S. Takeuchi, E. Kuramoto, and T. Suzuki:Acta Met., 1972, vol. 20, pp. 909- 15.
R. L. Smialek and T. E. Mitchell:Phil. Mag., 1970, vol. 22, pp. 1105–27.
E. Fromm and H. Jehn:Vacuum, 1969, vol. 19, pp. 191–97.
R. L. Smialek: Ph.D. Thesis, Case Western Reserve University, 1970.
H. Lachenmann and H. Schultz:Scripta Met., 1973, vol. 7, pp. 155–60.
G. L. Webb: Ph.D. Thesis, Case Western Reserve University, 1973.
T. E. Mitchell:Phil. Mag., 1968, vol. 17, pp. 1169–94.
S. Goods, J. Shields, and T. E. Mitchell: unpublished research.
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Formerly Graduate Student in Metallurgy and Materials Science at Case Western Reserve University
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Webb, G.L., Gibala, R. & Mitchell, T.E. Effect of normal stress on yield asymmetry in high purity tantalum crystals. Metall Trans 5, 1581–1584 (1974). https://doi.org/10.1007/BF02646329
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DOI: https://doi.org/10.1007/BF02646329