First-principles Investigation on Phase Stability and Elastic Properties of β-Ti1-x-y-z NbxZrySnz Alloys

摘要

The phase stability and elastic properties of β-type Ti1-x-y-zNbxZrySnz(x,y,z=0. 0,0. 0625,0. 125,0. 25,and 0. 5) alloys were investigated under the framework of first-principles. Results indicate that alloying elements Sn and Nb can obviously increase the stability of β phase and decrease the elastic moduli of β-Ti, while alloying element Zr has relatively weak influence on these properties. Zr makes the β-Ti unstable. Electronic structures were analyzed to clarify influence mechanisms of alloying elements on stability and elastic properties of β-Ti. The electronic structures were strongly affected by the alloying elements. The decreasing of total density of states at Fermi energy level and the moving of bonding peaks toward valence band make the Ti-Nb and Ti-Sn binary alloy more stable than the Ti-Zr alloy and β-Ti. The mechanical stabilities and elastic properties of the considered alloys were evaluated based on the calculations of the elastic constants of binary and ternary β-type titanium alloys. Although Zr and Sn contained binary alloys did not satisfy the mechanical stability criteria,but combining with Nb significantly decreases elastic moduli and increases mechanical stability of β-Ti.