The Effect of TiN-TiB 2 on the Microstructure, Wear, and Nanoindentation Behavior of Ti6Al4V-Ni-Cr Matrix Composites

The influence of ceramic (TiN and TiB 2 ) particles on the densification, microstructure, wear, and nanoindentation behavior of titanium matrix composites produced by spark plasma sintering was investigated. The results showed that the relative density of the Ti6Al4V-Ni-Cr-matrix composite with TiN and TiB 2 was reduced from 99.51 to 95.33%. The microstructural analysis revealed that the reinforcements were dispersed uniformly within the composite, demonstrating the existence of lamellar (α and β phase) and bimodal structures. The average microhardness value gradually increased from 378 to 707 HV 0.2, while the coefficient of friction ranged between 0.3 and 0.65. Furthermore, the material resisted the wear mechanism with improved wear resistance. The decreased frictional coefficient exhibited by the reinforced composite might be attributed to the oxide-layer formation, which served as a lubricant reducing friction between the two gliding surfaces of the material. The nanohardness values ranged from 6363.3 to 10,343 MPa, while the reduced-elastic-modulus values varied from 122.9 to 158.93 GPa.