Kinks in the a/2 screw dislocation in Ta

Abstract

We study the structure and formation energy of kinks in the 1/2a〈111〉 screw dislocations in metallic Tantalum (Ta) using molecular dynamics with a first principles based many-body interatomic potential. In our study, four a/3〈112〉 kinks are constructed in a quadrupole arrangement in the simulation cell. To the simulation cell, we impose periodic boundary conditions in the directions perpendicular to the [111] direction and fix boundary condition in the [111] direction. We find that two, energetically equivalent, core configurations for the 1/2a〈111〈 dislocation lead to 8 distinguishable single kinks and 16 kinds of kink pairs. The different mismatches of the core configurations along [111] direction attributed to the differences in the formation energy for various types of kinks. Formation energies for all possible kinds of isolated single kinks and kink pairs have been determined. It was found that 0.730 eV was the lowest energy cost to form a kink pair in the a/2〈111〉: screw dislocation in Ta.