Microstructure evolution and mechanical properties of TIG cladded TiB reinforced composite coating on Ti-6Al-4V alloy

Tungsten Inert Gas (TIG) cladding process employing pre-sintered 11.8 wt.% TiB2/Ti-6Al-4V composites as cladding material was carried out to produce wear-resistant coating on Ti-6Al-4V substrate. It was found that high quality composite coating consisting of heterogeneously distributed coarse primary TiB phase, fine eutectic TiB whisker (TiBw) and highly refined Ti-6Al-4V grains was obtained. Maximum micro-hardness of 800 HV0.2 was achieved when the coating was fabricated at an optimized heat input of 120 A, which is 128% higher than that of the Ti-6Al-4V matrix (351 HV0.2) heat input resulted in decrease in hardness of the coating on account of the enhanced dilution of the TiB phase. Dry sliding wear test revealed that the coefficient of friction (COF) of the optimized coating (0.36) was considerably lower than that of the substrate (0.48), indicating remarkable improvement in wear resistance by the composite coating. It is thus concluded that the TIG cladding process using pre-sintered 11.8 wt.% TiB2/Ti-6Al-4V composites as cladding material can be considered as a feasible low cost approach to enhance the properties of Ti alloys.