Structure Stability and Elastic Properties of β Type Ti-X (X=Nb, Mo) Alloys from First-Principles Calculations

The phase stability, the elastic constant and the electronic structure of Ti-X (X=Nb, Mo) alloys having bcc structure were studied from first-principles calculations by the method of supercell and the projector augmented wave within the generalized gradient approximation. The elastic moduli of the polycrystal alloys were estimated from the elastic constants of the single crystal by the Voigt-Reuss-Hill averaging method. The results reveal that Nb and Mo contents have a significant influence on the phase stability and the elastic properties of the β type Ti-X alloys. The phase stability, the elastic constants, the elastic modulus and the shear modulus of β type Ti-X alloys increase with the X content increasing. The lowest elastic modulus of the alloys is achieved as the X content is about 25%. Moreover, the phase stability of the alloys was discussed based on the calculated density of state (DOS).