Mechanical properties and phase stability of Ti-Nb-Ta-Zr-O alloys

Abstract

The effects of niobium and oxygen content on the mechanical properties, β phase stability and elastic deformation behavior of Ti-Nb-Ta-Zr-O alloys were investigated by employing tensile tests, microstructure observations and XRD analysis. The basic composition of the tested alloys used was Ti-36%Nb-2%Ta-3%Zr-0.3%O (mass%), with the other alloys having lower niobium content (from 32% to 36%) and higher oxygen content (0.5%). Orthorhombic a" was observed in the specimens with lower niobium content. Work hardening and elastic deformation behavior in the specimens with lower niobium (33% to 34%) and higher oxygen (0.5%) contents are similar to those of the alloy with basic composition; these specimens showed little work hardening and non-linearity in the elastic range of tensile deformation. The phase configuration analysis of these specimen alloys does not show the presence of any peaks other than the β phase before and after cold working. The cold worked Ti-32%Nb-2%Ta-3%Zr- 0.5%O has a Young's modulus of 55 GPa, a tensile strength of 1370MPa and a tensile elongation of 12%. After heat treatment at 623 K for 600 s, the tensile strength of the alloy reaches 1500 MPa. with a Young's modulus of 58 GPa and a tensile elongation of 10%. © 2007 The Japan Institute of Metals.