Transmutation elements Re/Ta effect on vacancy formation and dissociation behavior in W

TL;DR

This study uses first-principles calculations to explore how transmutation elements Re and Ta influence vacancy formation, migration, and clustering behaviors in tungsten, which are critical for plasma-facing materials in nuclear environments.

Contribution

It provides new insights into the effects of Re and Ta on vacancy dynamics in tungsten, highlighting their roles in vacancy cluster growth and dissociation processes.

Findings

Re increases vacancy formation likelihood in W.

Re promotes vacancy cluster growth, Ta suppresses it.

Vacancy dissociation is easier starting from a single vacancy.

Abstract

Transmutation elements are the essential products in plasma facing materials tungsten, and have further effects on point defects evolution resulted by radiation. Here, transmutation elements Re and Ta atoms have been selected to assess the effects on property of vacancy and vacancy cluster in W material via first-principles calculations. The formation energy indicates mono-vacancy is more likely to form in W-Re system than pure W and W-Ta system. Both Re and Ta have reduced the diffusion barrier energy in the mono-vacancy migration. The calculation presents that vacancy cluster prefers to grow up by combining another vacancy cluster relative to a single mono-vacancy. Re is favorable to the nucleation and growth of vacancies clusters, while Ta has a suppressive effect on the aggregation of small vacancy cluster. The emphasis analysis is obtained according the volumetric dependent strain. Vacancy dissociation calculations show that the dissociation of vacancy clusters is easier to begin with a single vacancy dissociation process.