Interaction of Parallel Dislocations in a Hexagonal Crystal

Abstract

Based on the theory of anisotropic elasticity, the stress field of a single dislocation, the force between two parallel dislocations, and the stress field of various types of infinite dislocation walls and arrays are fully analyzed for a hexagonal crystal. The attraction sector of an edge dislocation with respect to another edge dislocation of the same sign is no longer the half-quadrant as in the isotropic case. For graphite crystals the attraction sector is about 70° instead of 45°. The force between two parallel screw dislocations is not central. A tangential component exists, being zero along x and y axes. The tangential force will retard the formation of screw dislocation arrays along any plane except those parallel or normal to the basal plane. Cross slip may be aided or opposed by this force, depending on the direction of applied stress. The stress field of an infinite dislocation wall or array, either parallel or normal to the basal plane, has similar characteristics to those from isotropic treatment, although their magnitudes and geometries may differ considerably. Numerical data of six important material constants are tabulated for many common hexagonal crystals.