Strength-ductility synergy strategy of Ti6Al4V alloy fabricated by metal injection molding

Interstitial oxygen (O) contamination is still a huge obstacle for metal injection molding (MIM) titanium alloys. Herein, we successfully solve this critical problem by regulating the thermal debinding temperature and adding the oxygen scavenger LaB6. The result shows that the surface oxide layer (with the thickness of 13.4±0.5 nm) of Ti6Al4V powder begins to dissolve into Ti matrix within the temperature range of 663-775°C. Reducing the thermal debinding temperature and adding LaB6 powder can collectively prevent O contamination for MIM Ti alloys. Benefit from the decrease of dissolved O content, the slips of mixed anddislocations are effectively accelerated, thus achieving an increase in ductility. Moreover, the grain refinement and in situ formed TiB whiskers and second-phase La2O3 particles contribute to the improvement in strength. The fabricated MIM Ti6Al4V sample exhibits the excellent mechanical properties, with the ultimate tensile strength of 967±5 MPa, yield strength of 866±8 MPa and elongation of 21.4±0.7%. The tensile properties are an outstanding practice in the reported literatures for MIM Ti6Al4V alloys. This study provides an effective guidance for the development of high-performance MIM Ti alloys and other metal materials.