Mechanical properties and defective effects of bcc V–4Cr–4Ti and V–5Cr–5Ti alloys by first-principles simulations

V–(4–5) wt.% Cr–(4–5) wt.% Ti alloys are important candidate structural materials for the first-wall and blanket in future fusion reactor. Thus it is necessary to study the fundamental mechanical properties and the irradiation effects of the V-based alloys. Within a random solid solution model, the elastic constants and ideal strength of the V–4Cr–4Ti and the V–5Cr–5Ti alloys were calculated and compared with those of pure V solid. According to the theoretical Cauchy pressure and the ratio of bulk modulus and shear modulus, both alloys exhibit good ductility. Within the 250-atom supercell, inclusion of one vacancy defect or one interstitial H (He) atom will further enhance the ductility of these alloys.

► V–4Cr–4Ti and V–5Cr–5Ti alloys exhibit better ductile behavior with regard to pure V solid.
► One vacancy or interstitial can soften bcc V–4Cr–4Ti and V–5Cr–5Ti alloys and enhance their ductility.