Effect of Sintering Environment on Microstructures and Mechanical Properties of Metal Injection Molding Ti-6Al-4V Alloys

We employed a water-soluble binder to form Ti-6Al-4V alloy through metal injection molding and studied the effects of sintering (under Ar and various vacuum conditions) on the microstructure and mechanical properties of the material. The density was measured using the displacement method. The microstructure and mechanical properties of the alloy were characterized using optical microscopy, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy and a universal testing machine. The results indicate that sintering the Ti-6Al-4V alloy under vacuum improved relative density and mechanical properties more than under the Ar environment. Furthermore, high-vacuum sintering significantly enhanced the relative density and mechanical properties of the material. At < 10⁻³ Pa vacuum pressure, the material exhibited optimal relative density (97.6%), tensile strength (1022.7 MPa) and elongation (6.4%). Also, the impurity contents were 0.071%, 0.25% and 0.012% for carbon, oxygen and nitrogen, respectively, which met the impurity content requirements of Ti-6Al-4V alloy.