Effect of TiC content on the microstructure and mechanical properties of Ti-30Mo-xTiC composites

Abstract

TiC reinforced titanium matrix composites are promising for advanced applications. In this study, the Ti-30Mo-xTiC composites with the TiC content of 0, 0.5, 2.5 and 5 wt% were prepared using a powder metallurgy method. The results showed that TiC in Ti-30Mo exhibited a stoichiometric ratio of Ti to C over 1:1, along with demonstrating a semi-coherent lattice relationship with the β-Ti matrix lattice. Further, the excess C element diffused from the TiC particles to the matrix at the interface with large solid solubility, thus, promoting the sintering densification. Compared with Ti-30Mo, the composites with TiC addition revealed much higher relative density. Increasing the TiC content could increase the matrix microhardness and elastic modulus, however, the ultimate tensile strength and elongation were decreased. The mechanical properties were improved owing to the cooperative effect of densification, TiC particle reinforcement, solid solution of Mo and C elements and semi-coherent interface. As a result, the Ti-30Mo-0.5TiC composite presented an excellent combination of properties: matrix microhardness of 294 HV0.3, ultimate tensile strength of 820 MPa, elongation of 6.5% and elastic modulus of 112 GPa.