First-principles study on the segregation behavior of C/N/O interstitial impurities in TiVTaNb

Refractory high entropy alloys with outstanding high temperature properties and irradiation tolerance have been proposed as potential structural materials for advanced nuclear systems. However, the stability and mechanical properties of the alloys will be significantly reduced by the interstitial impurities such as C, N and O, through the component segregation and precipitate formation. To understand this process, the formation and segregation energy of interstitials in TiVTaNb RHEA are studied by using first-principles calculations. We found that interstitial impurities prefer to segregate around Ti atoms, and C/N atoms tend to co-segregate with O atoms. Moreover, the precipitates with higher O content are more stable than the others. These results will be helpful to unveil the mechanism of the precipitate formation in RHEAs.