Nanoindentational and conventional mechanical properties of spark plasma sintered Ti-Mo alloys

The densification behavior and mechanical properties of spark plasma sintered titanium-molybdenum alloys were investigated in this paper. All Ti-(4, 8, 12, 16, and 20 wt%) Mo samples were sintered at 1200 ◦C for 5 min under 50 MPa. A significant relative density of 99.9% was secured for the Ti-based alloy with 16 wt.% Mo. The overall trend of hardness was similar to that of the relative density as Ti-16 wt.% Mo alloy showed the highest hardness values of 372 HV₃₀ and 592 HV_0.3 in macro (30 kg) and micro scales (300 g), respectively. Maximum ultimate tensile strength values (852 MPa at room temperature and 600 MPa at 600 ^◦C) belonged to the Ti-8 wt.% Mo sample. Such an observation was related to the formation of β- Ti phase and the strain-induced transformation phenomenon. The highest flexural strength of ∼2 GPa belonged to the Ti-12 wt.% Mo alloy, which may be a result of solid solution formation between Ti and Mo. Finally, average values of nano hardness, elastic modulus, and stiffness of various phases available in the samples with 12 and 20 wt% Mo were calculated through nano-indentation technique and the former specimen presented higher values in all the mentioned qualities.