Motion of a 1/3〈 11 23〉 screw dislocation in a model h.c.p. lattice

A computer-simulation study has been made of the behaviour of a 1/3〈1123〉 screw dislocation under the effect of applied shear stresses, using a truncated Lennard-Jones potential. As has been shown elsewhere, the stress-free dislocation assumes various core configurations spreading over {1011}, {1122} or several combinations of these planes. Regardless of its core configurations, the dislocation glides on the {1122} plane under the shear stress applied in the direction corresponding to the compression parallel to the c axis, while it glides on the {1011} plane under the shear stress applied in the opposite direction. The result is discussed in the light of the macroscopic behaviour of h.c.p. metals.