CONSTITUTIVE MODELING OF LL2 INTERMETALLIC CRYSTALS

A dislocation model of the hardening of L1(2) intermetallics is propos ed. Hardening is presumed to be the net effect of point obstacles oppo sing the motion of dislocations. Two sources of point obstacles are co nsidered: forest dislocations and cross-slip pinning. Forest hardening is assumed to be the only operative hardening mechanism for cubic sys tems. Octahedral systems are presumed to be subject to both forest har dening and hardening by cross-slip pinning. The rate of obstacle gener ation by die latter mechanism is taken to be proportional to the rate of cross-slip. The activation enthalpy for cross-slip is taken from th e work of Paidar et al. (V. Paidar, D. P. Pope and V. Vitek, Acta Meta ll., 32 (3) (1984) 435). Detailed comparisons between theory and exper iment are given. The theory correctly predicts salient aspects of the behavior of L1(2) intermetallics, including features which had previou sly been interpreted as indicative of ''non-Schmid'' yield behavior.