In situ preparation of Ti/CaB6 composites via powder metallurgy: microstructure, mechanical and tribological properties improvement

Titanium (Ti) alloys suffer from poor mechanical strength and inferior wear resistance. Herein, we introduced the calcium hexa boride (CaB6) into Ti matrix to manufacture high-strength and high-wear in situ Ti matrix composites (TMCs) by powder metallurgy method. The effects of CaB6 addition on the microstructure, mechanical and tribological properties of TMCs were studied. Results show that the formation of hard in situ TiB and nano-size CaTiO3 particles contributes to a remarkable refinement of average grain size from 163 mu m in pure Ti to 74 mu m in Ti-1.0 wt.% CaB6 composite. The hardness is significantly increased from 191 +/- 15 HV in pure Ti to 321 +/- 13 HV in Ti-0.8 wt.% CaB6 composite. The Ti-0.8 wt.% CaB6 composite obtains the best comprehensive mechanical properties with an ultimate tensile strength of 740.3 +/- 28.3 MPa, yield strength of 598.4 +/- 23.1 MPa and elongation of 10.6 +/- 1.5% and displays the optimal wear resistance with friction coefficients of 0.45, 50% less than pure Ti, under constant conditions (3 N, 0.03 m/s).