Microstructure and properties of TiC reinforced composite coating fabricated on Ti alloy by GTAW

A metal matrix composite coating reinforced by TiC particulates has been successfully fabricated utilizing the in-situ reaction of pre-placed C powder on Ti alloy by gas tungsten arc welding (GTAW)process.The microstructure of the coating was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD)and energy-dispersive spectrum (EDS).The growing mechanism of TiC was discussed.Microhardness and wear resistance at room temperature of the composite coating were examined by means of Microhardness Tester and Wear Tester respectively.The results show that microstructure of the composite coating is uniform and the fine TiC exhibites dendrite and strip shapes.The composite coating reinforced by in-situ TiC apparently improves surface hardness of Ti alloy, the average microhardness can reach HV700, and its gradient distribution appears.Wear resistance of the composite coating is about 10.5 times of Ti alloy's substrate.