Mechanical properties of low-cost beta-type Ti-Mn alloys fabricated by metal injection molding

Ti-10Mn and Ti-14Mn alloys were fabricated by metal injection molding method. Their microstructures and mechanical properties, including tensile properties, Young's modulus, and hardness, were investigated as functions of sintering temperature. The microstructures of the sintered Ti-10Mn and Ti-14Mn alloys have strong dependence on sintering temperature. Relative densities and grain diameters of the sintered Ti-10Mn and Ti-14Mn alloys increase with increasing sintering temperature. Moreover, all Ti-10Mn and Ti-14Mn alloys sintered at 1373 K, 1423 K, and 1473 K consist of a β phase and a needle-like α phase, whereas Ti-14Mn alloys sintered at 1273 K and 1323 K consist of only a β phase. The tensile strengths of the sintered Ti-10Mn and Ti-14Mn alloys archive a maximum of 860 MPa and 886 MPa, respectively. However, elongation of the sintered Ti-10Mn and Ti-14Mn alloys are approximately 5% and 1%, respectively. Ti-14Mn alloy sintered at 1273 K shows the lowest Young's modulus (76 GPa) among all the sintered Ti-10Mn and Ti-14Mn alloys. The Vickers' hardness of the sintered Ti-10Mn alloys is almost constant at approximately 320 Hv. On the other hand, the Vickers hardness of the sintered Ti-14Mn alloys increases from approximately 300 Hv to 370 Hv with increasing the sintering temperature from 1273 K to 1473 K. The tensile properties of the sintered Ti-10Mn and Ti-14Mn alloys are poorer than that of Ti-6Al-4V ELI alloy; the ductility in particular is much lower. However, the Young's modulus and hardness of the sintered Ti-10Mn and Ti-14Mn alloys are lower and higher, respectively, than commercial Ti-6Al-4V ELI alloy.