In-situ synthesis of TiC/Ti composite coating by high frequency induction cladding

The in-situ formation of TiC/Ti composite coating was achieved by induction cladding (IC) approach. The powder mixture of 70 at% Ti and 30 at% graphite were preplaced on a Ti6Al4V substrate and irradiated with a high frequency induction heating coil in Ar atmosphere. The cladded coating exhibited a practically dense and pore-free microstructure with metallurgical adherence to the substrate. Fine titanium carbides (TiC) were uniformly formed in the coating, which were confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) analysis. Two temperature peaks within the coating indicates the induction cladding process is different from the point heating sources. Dissolution-precipitation mechanism is used to explain the formation of the composite coating and the in situ synthesis of the TiC particle reinforcements. The nanoindentation hardness of the TiC particles is about 22 GPa, which makes the microhardness of the composite coating (600 HV0.2) nearly twice the microhardness of the Ti6Al4V substrate (340 HV0.2). The hardness evolution of the composite coating is evaluated by the rule of mixtures and the predicted results are consistence with the measured ones.