Hierarchy of the Dislocation Glide Systems in Titanium Alloys by Atomic Simulation

摘要

Titanium (Ti) alloys are important materials for industrial applications and a since few years, the major aim is to improve the properties and performances when these alloys are subjected to extreme conditions of deformation. Simulations predicting mechanical properties need the fundamental parameters of the plasticity like the critical resolved shear stresses (CRSS). The CRSS represent the strain applied to a dislocation in the glide plane and the glide direction to make it cessile. There exist,in HCP materials,many glide planes (basal prismatic and pyramidal planes). We have studied the hierarchy of dislocation glide systems in titanium alloys (CRSS) in five planes. We have used two different modeling approaches. The first approach is by using the stacking fault energy maps (gamma surfaces) obtained by Molecular Dynamics (MD) and ab initio calculations. The second is to calculate directly the CRSS by MD simulations based on EAM potentials. The CRSS for slip in the-direction for the basal,prismatic (type 1) and pyramidal (type 2) planes are obtained. Finally,we discuss the hierarchy of the glide systems with the energy criterion of the gamma surfaces and with the CRSS values and we compare with both experimental and modeling data from the literature.