Application of anisotropic elasticity theory to the plastic deformation in hexagonal zinc

Abstract

The elastic energies of dislocations in the edge orientation are calculated for the various possible slip systems and the type twin in hexagonal close-packed zinc crystal by applying anisotropic elasticity theory. The interaction between a pair of twin dislocations is derived from the stress field around a twin dislocation and is found to be non-centrosymmetrical unless they lie on the same atomic plane. The results are applied to a discussion of the feasibility of dislocation dissociation processes and interpreting the shapes of advancing twin boundaries. Certain dislocation dissociation processes which are energetically indeterminate from the isotropic elasticity point of view become feasible. The observed shapes of some twin boundaries agree with the calculated results. The energy associated with a coherent twin boundary is estimated from the observed angle between a coherent and an incoherent twin boundary to be 1·4±+0·4 ergs/cm².