It was recalled that the shear yield stress, τ, due to the {11▪2}<¯1¯1▪3> second-order pyramidal slip system in hexagonal close-packed Cd crystals increased with increasing temperature. This result was explained by positing 2 thermally activated processes: the dissociation of a (c+a) edge dislocation with a Burgers vector of 1/3<¯1¯1▪3> into a c sessile dislocation and an a glissile basal dislocation, and the subsequent immobilization of the (c+a) edge dislocation. The consequent double cross-slip of (c+a) screw dislocations which had to be activated thermally by an increment of applied stress to increase the propagation velocity of slip band width. Moreover, τ was strongly affected by the direction of the applied shear force due to second-order pyramidal slip in Cd. The anomalous behaviors of yielding would then be caused by the non-symmetrical core structure of the (c+a) dislocation, due to the lattice heterogeneity in hexagonal close-packed metals.

Effect of Temperature and Shear Direction on Yield Stress by {11▪2}<¯1¯1▪3> Slip in HCP Metals. H.Tonda, S.Ando: Metallurgical and Materials Transactions A, 2002, 33[3A], 831-6