Computer simulation of images of undissociated dislocations in hexagonal metals

Abstract

The computer programme originated by Head (1967) has been modified for hexagonal crystal structures. Computed and experimental images have been matched for edge and mixed dislocations with Burgers vectors a/3 and lying in the basal plane of magnesium. The programme has been used to investigate the general form of dislocation images in common c.p.h. metals, allowing for elastic anisotropy. When g. b = 0 dislocations with Burgers vectors b = a/3, a/3 and c and having particular line directions behave as if the material were elastically isotropic. For those combinations of Burgers vectors and line directions for which elastic anisotropy must be considered its effect is to lower the value of g. b ∧ u at which the change from invisibility to visibility occurs when g.b = 0.