Investigation of Glide Properties in Hexagonal Titanium and Zirconium: An Ab Initio Atomic Scale Study

Abstract

In this work we present ab initio atomic-scale simulations based on the density functional theory of stacking faults and of the structure of the (a) screw dislocation core in hexagonal Zr and Ti. The basal, prismatic, pyramidal π₁ and π₂ gamma-surfaces were investigated and the energy profiles along (a) and (c+a) Burgers vectors were determined. The results clearly indicate preferential prismatic spreading of screw dislocation cores suggesting a primary prismatic glide. The ab initio simulations are in an overall good agreement with previous tight binding ones¹ although differences concerning the atomic relaxation around prismatic faults have been observed. Some environment effects on dislocation glide properties have been investigated through the study of the hydrogen effect on the stacking fault excess energies. Hydrogen in solid solution induces significant reductions of the stacking fault energy and should promote enhanced planar prismatic glide.