Microstructural evolution, mechanical properties and wear behavior of in-situ TiC-reinforced Ti matrix composite coating by induction cladding

In this work, the in-situ fabrication of TiC/Ti composite coatings is realized by melting a mixture of Ti and graphite powders on Ti6Al4V substrate by a high-frequency induction heating coil under Ar atmosphere. The microstructural evolution, phase changes, micro/nano mechanical properties, and tribological behavior of the TiC/Ti composite coatings are systematically investigated. The in-situ growth mechanism of TiC and wear resistance mechanism of the TiC/Ti composite coatings are also discussed from the viewpoints of Ti–C binary phase diagram, composition of raw powders, crystal structure of TiC and solidification conditions. The results indicate that the dissolution-precipitation mechanism dictates the in-situ growth of TiC reinforcements. Moreover, the morphology, dimensions and distribution of TiC phase in the TiC/Ti composite coating are strongly influenced by the composition of raw powders, crystal structure of TiC and induction cladding process. The high induction power and optimal coil scanning speed generate less heat input for the coating formation and fast solidification speed, resulting in fine TiC reinforcements, a narrow interface transition region and a heat-affected zone. Furthermore, the in-situ formation of reinforcements endows high hardness, good elasticity and excellent tribological properties to the TiC/Ti composite coatings.