First-principles insights into strain-mediated He migration and irradiation resistance in W-Ta-Cr-V complex alloys

Abstract

Abstract High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation. Among them, tungsten-based alloys demonstrate exceptional potential owing to their superior irradiation resistance. Recent experimental studies have demonstrated that WTaCrV alloys exhibit excellent irradiation resistance under helium (He) ion irradiation. However, the underlying mechanisms, especially the migration behavior of He atoms, remain unclear. In this work, the influences of uniaxial tensile and compressive strain on He migration in W-Ta-Cr-V complex alloys have been systematically studied through first-principles calculations. Our results demonstrate that He atoms preferentially occupy the tetrahedral interstitial sites, with interstitial formation energies significantly reduced compared to pure W. The introduction of Ta, Cr, and V alloying elements markedly increases the He migration barriers, effectively suppressing He diffusion. Compressive strain increases the migration barriers, inhibiting He bubbles nucleation and growth, while tensile strain decreases the barriers, facilitating bubble formation. Compared to pure W, the W-Ta-Cr-V alloys exhibit both lower He interstitial formation energies and higher migration barriers, with further enhancement under compressive strain. Specifically, compressive strain of 6% increases the He migration barrier of the W-Ta-Cr-V alloy by 0.166 eV, which further widens the difference relative to pure W. These findings provide a theoretical explanation for the superior irradiation resistance of tungsten-based alloys observed experimentally and promote the understanding of irradiation damage in these alloys under strain.

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