On the character of self-interstitial dislocation loops in vanadium

Abstract

Molecular statics and molecular dynamics simulations based on a new Finnis–Sinclair potential were used to investigate the energy and structure of self-interstitial atom (SIA) dislocation loops in vanadium. The results are compared to experimental observations and recent results in ferritic alloys which detail the formation mechanism responsible for the nucleation and growth mechanism of ⟨100⟩ dislocation loops. The SIA dislocation loops in vanadium are composed of ⟨111⟩ split dumbbells and crowdions. The clusters can be described as perfect prismatic dislocation loops with Burgers vector b = 1/2⟨111⟩. As the loops grow, SIAs fill successive jogged-edge rows with minimum free-energy cusps corresponding to unjogged filled hexagonal shells. Notably, dislocation loops of ⟨100⟩ Burgers vector are not observed in vanadium, and these results provide a basis for understanding the experimental observations.

Acknowledgements

This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.