In situ preparation of Ti/CaB 6 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 (CaB 6 ) into Ti matrix to manufacture high-strength and high-wear in situ Ti matrix composites (TMCs) by powder metallurgy method. The effects of CaB 6 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 CaTiO 3 particles contributes to a remarkable refinement of average grain size from 163 μm in pure Ti to 74 μm in Ti–1.0 wt.% CaB 6 composite. The hardness is significantly increased from 191 ± 15 HV in pure Ti to 321 ± 13 HV in Ti–0.8 wt.% CaB 6 composite. The Ti–0.8 wt.% CaB 6 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).