Effects of Alloying Elements on the Microstructure and Mechanical Properties of Novel α+β Dual-Phase Ti-Nb-Ta-Zr Alloys

A series of novel α+β dual-phase Ti-Nb-Ta-Zr (Ti-(3, 5) wt.% Nb-(2, 10, 13) wt.% Ta- 2 wt.% Zr) alloys with low elastic modulus were designed by reducing the stability of β-phase under the guidelines of ab initio calculations and d-electronic theory. The alloys exhibit typical characteristics of α+β dual-phase microstructure. Among the alloys, Ti-3Nb-13Ta-2Zr alloy shows the lowest Young’s modulus (61 GPa) with highest ultimate tensile strength (779 MPa), mainly attributed to the combination of α + β dual-phase structure with stress-induced α" martensite. Moreover, {0001} α α and {001} β β textures also contribute to the reduction of elastic modulus of the alloy. Atom probe tomography analysis reveals that the elemental partitioning between α and β leads to the enrichment of solutes (Nb, Ta, Zr) in the β phase, and the elements distribution in the β phase is uneven.