Tensile property and deformation structure at elevated temperatures in Ti-Mo alloy

The purpose of this study is to investigate the tensile property and the deformation structure of Ti-(8,14,20)mass%Mo binary alloy at elevated temperatures. The metastable phases formed by quenching from 1223K were investigated by optical microscopy, X-ray diffraction, and transmission electron microscopy. Ti-8mass%Mo alloy was consisted of α″ martensite structure, Ti-14mass%Mo alloy was β + commensurate ω structure, and Ti-20mass%Mo alloy was β + incommensurate ω structure. The phase transformation behavior during heating process was investigated by differential scanning calorimetry in these specimens. Tensile tests of these specimens were performed at elevated temperatures from room temperature to 723K, and the deformation structure was observed by optical microscope. Though the elastic incline became lower at 623K in Ti-8mass%Mo alloy, it was almost the same in Ti-14mass%Mo and Ti-20mass%Mo alloy. Yield stress decreased at elevated temperatures in Ti-8mass%Mo and Ti-20mass%Mo alloy, but it was little change in Ti-14mass%Mo alloy. The deformation structure was also different at each composition and deformation temperature. These changes of the tensile property and the deformation structure that were affected by the deformation temperature were interpreted using the phase stability of β phase including these metastable phases.