Mechanical property enhancement of high-plasticity powder metallurgy titanium with a high oxygen concentration

Highlights: • High-plasticity PM Ti material with high O content is prepared with ZrO₂ addition. • The strength-ductility trade-off dilemma of PM titanium alloy is broken. • Ti-1.0 wt% ZrO₂ sample (0.56 wt% O) has UTS of 824 MPa and EL. of 15%. • Zr and O atoms fully dissolve in the Ti matrix, leading to lattice constant change. • The strengthen effect of ZrO₂ is calculated as 146.7 MPa/wt% ZrO₂. -- Abstract: High-plasticity titanium materials with high oxygen content were prepared by powder metallurgy (PM) and hot rolling, using pure Ti and ZrO₂ powder as raw materials. Completely dissolved oxygen and zirconium atoms resulted in the lattice constant change, thereby increasing the strength. Although the oxygen content was up to 0.56 wt% (much higher than the oxygen threshold of 0.33 wt%), PM Ti still exhibited high plasticity. The Ti-0.5 wt% ZrO₂ sample (0.43 wt% O) had UTS of 737 MPa and EL. of 28%, while the Ti-1.0 wt% ZrO₂ sample (0.56 wt% O) had UTS of 824 MPa and EL. of 15%. Compared to pure Ti, the addition of 0.5 wt% ZrO₂ resulted in a noticeable increase in UTS (increased by 9%) and EL. (increased by 19%). The strength-ductility trade-off dilemma of PM Ti alloy was broken. The formation of fine and equiaxed dynamic recrystallized grains may be one of the reasons that increased the ductility. The reinforcement effect of ZrO₂ was calculated as 146.7 MPa/wt% ZrO₂.