An atomic scale study on self-interstitial formation and diffusion behaviors in TiVTa and TiVTaNb concentrated solid-solution alloys

The formation and diffusion behaviors of self-interstitial defects in TiVTa and TiVTaNb concentrated solid -solution alloys (CSAs) are studied systematically by first-principles calculations and molecular dynamics simu-lations. It is found that [1 1 1] VV and TiV dumbbells are the most stable configurations in TiVTa-based CSAs, the formation energies of self-interstitials in TiVTaNb are higher than that in TiVTa CSAs. Local chemical envi-ronment can affect the formation of interstitials, where interstitials prefer V-rich environment. Larger local lattice distortion in TiVTa can lead to an irregular energy landscape and make it easier to form interstitials than in TiVTaNb. Compared with pure V, the diffusivity of interstitial is much lower than in TiVTa-based CSAs, which is related to the specific stability of interstitial configurations and lattice distortion. The preferential elemental diffusion is also observed which can be demonstrated by the interstitial formation preferences. Significant lattice distortion caused by atomic size mismatch in TiVTa-based CSAs can hinder the formation of interstitials, resulting in chemically biased diffusion and preferential diffusion pathways of interstitials.

Automated summary

The formation and diffusion behaviors of self-interstitial defects in TiVTa and TiVTaNb concentrated solid-solution alloys (CSAs) are systematically studied. Stability and formation energies differ in TiVTa-based CSAs and TiVTaNb alloys due to the local chemical environment and lattice distortion. The diffusivity of interstitials is lower in TiVTa-based CSAs compared to pure V, and preferential elemental diffusion is observed as a result of lattice distortion in TiVTa-based CSAs.