Effect of temperature and shear direction on yield stress by {1122}〈1123〉 slip in HCP metalsslip in HCP metals

ISSN： 1543-1940

Source： Metallurgical and Materials Transactions A, Vol.33, Iss.13, 2002-03, pp. : 831-836

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The yield shear stress τ _y due to second-order pyramidal slip system in cadmium, zinc, and magnesium hcp crystals increased with increasing temperature. This results is interpreted by two thermally activated processes as follows: (1) the dissociation of a (c+a) edge dislocation with a Burgers vector of into a c sessile dislocation and an a glissile basal dislocation, and the subsequent immobilization of the (c+a) edge dislocation; (2) consequently, the double-cross slip of (c+a) screw dislocations must be activated thermally by an increment of applied stress to increase propagation velocity of slip band width. Moreover, τ _y is affected strongly by a direction of applied shear force due to second-order pyramidal slip in zinc as well as in cadmium. The anomalous behaviors of yielding would be caused by the nonsymmetrical core structure of the (c+a) dislocation due to the lattice heterogeneity in hcp metals.