The influence of heat treatment processing on microstructure and mechanical properties of Ti-24Nb-4Zr-8Sn alloy by powder metallurgy

Different heat treatments, including quenching and hot isostatic pressing, were conducted on the Ti-24Nb-4Zr- 8Sn alloy fabricated by powder metallurgy, in order to improve its mechanical properties. As-sintered samples have high oxygen content over 3000 ppm, resulting in a phase precipitates and low ductility. But the mechanical properties can be improved by solution treatment at a suitable temperature and subsequent quenching. Although the treatment is only effective within a narrow temperature window ranging from 950 to 1000 degrees C, the treatment can completely eliminate the detrimental a phase and substantially improve the ductility of the alloy from 2% to 19.33%. In comparison, although the hot isostatic pressing can improve the density of the as-sintered alloy to nearly fully dense, it proves unable to remove the a phase from the material or improve its ductility alone.