Microstructures and Tensile Properties of Ti-6Al-4 V-(0, 2.5, 5, 7.5)Mo Alloys Manufactured by Metal Injection Molding

Ti-6Al-4 V is the most widely utilized titanium alloy. Mo is a β-stabilizing element, which can modify the microstructure and tensile properties of titanium alloys. In this work, the effects of Mo additions to Ti-6Al-4 V manufactured by metal injection molding were investigated. Sintering temperatures of 1100 and 1150 °C were employed to examine the microstructures and tensile properties. The tensile properties varied with Mo content and sintering temperature. Specifically, the ultimate tensile strength increased with Mo content at both temperatures. The strain to failure tended to decrease with Mo content when sintered at 1100 °C. However, at 1150 °C, the strain to failure significantly increased with a 2.5 wt pct Mo addition but decreased with the higher Mo additions. The strain to failure improved with a higher volume fraction of grain boundary α layers induced by Mo additions. However, at high Mo contents (> 5 wt pct Mo), the fracture was primarily governed by TiC. Hence, 5 wt pct of Mo addition is considered the threshold. In this study, Ti-6Al-4 V-2.5Mo sintered at 1150 °C exhibited the most optimal properties, making it an attractive choice for functional materials.