Helium behavior in W-Ta-Cr-V high-entropy alloy: An interatomic potential and molecular dynamics simulations

Abstract

Tungsten-based high-entropy alloys have demonstrated promising performance as materials for nuclear fusion. Understanding typical helium behavior in these alloys is crucial for assessing their resistance to helium ion irradiation and underlying mechanisms. In this study, we developed a W-Ta-Cr-V-He five-element interatomic potential and used it to examine helium behavior in the W₃₈Ta₃₆Cr₁₅V₁₁ alloy through molecular dynamics simulations. Our results reveal several notable differences between W₃₈Ta₃₆Cr₁₅V₁₁ and pure tungsten. Specifically, the formation and binding energies of helium clusters and helium-vacancy clusters in W₃₈Ta₃₆Cr₁₅V₁₁ are significantly lower than in pure tungsten, indicating reduced binding ability for helium atoms and a weaker self-trapping effect. Furthermore, the alloy exhibits a significantly higher diffusion energy barrier for a single interstitial helium atom, resulting in decreased helium mobility and further reducing the tendency for helium cluster formation. The study also highlights distinct mechanisms of helium bubble growth: in W₃₈Ta₃₆Cr₁₅V₁₁, helium clusters lead to the expulsion of interstitial atoms without forming dislocation loops, whereas in pure tungsten, dislocation loop emission accompanies helium bubble growth. Temperature-dependent simulations show that helium bubble nucleation is notably suppressed in W₃₈Ta₃₆Cr₁₅V₁₁ compared to pure tungsten, with weaker clustering of helium atoms observed at various temperatures. The developed W-Ta-Cr-V-He potential and the resulting data offer valuable insights into helium behavior in tungsten-based high-entropy alloys.