Tribological investigation of additive manufacturing medical Ti6Al4V alloys against Al2O3 ceramic balls in artificial saliva

Additive manufacturing Ti6Al4V alloys have found their potential applications in artificial teeth and hip joints. In this work, the relationships between wear resistance, hardness and microstructure of Ti6Al4V alloys fabricated using various routes were investigated in artificial saliva. The results indicate that comparing with wrought and wrought + heat treated (HT) samples, the as-SLMed samples with hcp-alpha' martensite and few bcc-beta phase exhibit higher hardness (similar to 410 HV) and better wear resistance. The as-SLMed samples, however, exhibit the worst wear resistance when wear direction is parallel to the molten pool line on XOZ-plane due to containing the softer fusion zone. Finally, the wear mechanism is discussed in detail, mainly including the abrasive and adhesive wear mechanism. The high hardness of matrix as well as the strong adhesion between the hardened layer, oxide layer and matrix are indispensable conditions for maintaining the optimum wear resistance.