Phase stability and elastic properties of β Ti–Nb–X (X = Zr, Sn) alloys: an ab initio density functional study

Abstract

Alloying effects of Zr and Sn on β phase stability and elastic properties in Ti–Nb alloys are investigated within the framework of first-principles density functional theory. Our results suggest that the stability of β phase can be significantly enhanced by the addition of Zr and Sn in Ti–Nb alloys. The computed results indicate that Zr and Sn behave as strong β stabilizers in the Ti–Nb system. The elastic properties are found to be altered considerably by the addition of ternary alloying elements (Zr and Sn). The computed elastic moduli of Ti18.75 at%Nb6.25 at%Zr and Ti25 at%NbxZr compositions are found to be lower than that for Ti18.75 at%Nb6.25 at%Sn and Ti25 at%NbxSn system. The lowest value of ∼54 GPa is obtained for Ti25 at%Nb6.25 at%Zr composition. Furthermore, the directional Young’s modulus is found to be in the order of E100 < E110 < E111 for all the compositions of Ti–Nb–Zr and Ti–Nb–Sn system.