First-principles calculations of transition metal–solute interactions with point defects in tungsten

Abstract

The interactions of solute atoms with point defects can modify the microstructure of materials and affect microstructural evolution, ultimately leading to macroscopic changes in the mechanical properties of materials. In this paper, we performed a series of first-principles calculations to quantify the intrinsic properties of transition metal (TM) solutes and their interactions with point defects in W, including vacancies and 〈111〉-crowdions. This work provides good explanations for recent experimental results on the influence of solute on radiation response and might aid future material design regarding the choice of alloy composition. We find that the early TM elements do not segregate together while the late elements tend to accumulate to form small clusters in dilute W alloys. The solute–point defect interactions are mostly attractive with a few exceptions, and can be well understood in terms of the combination of, and competition between, electronic effects and strain-relief effects, which are characterized by the solute electronegativity and atomic size, respectively. Solute atoms with larger electronegativity more favorably bond to the vacancy and the smaller ones prefer to bind to the 〈111〉-crowdion, and vice versa. The present results, together with previous experimental results, suggest that Re might be a relatively suitable alloying element compared to other possible candidates, and Ta seems suitable for adding in W–Re alloy to adjust the concentration of Re and Os.