The Effect of Oxygen on Mechanical Properties and Deformation Modes of Ti-2Al-xO Alloys at Different Temperatures

摘要

Ti-2A1 alloys were prepared to contain oxygen from 0. 06 to 0. 3(wt pct) and effect of oxygen on the strength and ductility as well as deformation modes were investigated at 77K (in liquid nitrogen), room temperature(RT) and 673K. The results show that oxygen has apparent effect on properties of Ti-2Al-xO alloys at low temperature and RT and the effect became less at 673K. Oxygen from 0. 06 to 0. 3 in Ti2A1 alloys increases the strength from 650MPa to 1250MPa, increasing by 600MPa. At 673K,the strength increase from 230MPa to 380MPa with the same oxygen content changes. At low temperatures, ductility decreases with increasing oxygen. Increasing temperature weakens the effect of oxygen on ductility and Ti-2Al-xO alloys show almost same ductility independent of oxygen concentration. The results also show that load drop (stress drop) occurs which means yield in plastic deformation of alloys at 673K, while load drop disappears at RT and 77K. This indicates that dislocation can escape from oxygen atmosphere in the lattice at high temperature. Typical dislocation patterns, such as dislocation bundles and cells, form in Ti-2Al-0. 06O alloy and only dislocation lines are found in Ti-2Al-0. 30 alloys.