Microstructure and properties of laser cladding TiC/TiAl composite coatings on γ-TiAl intermetallic alloy

To improve the wear resistance of the γ-TiAl intermetallic alloy, Ti-Al-TiC alloy powders were prepared on the surface of TiAl intermetallic alloy and then treated by a high power continuous wave CO₂ laser. TiC reinforced TiAl matrix composite coatings have been successfully synthesised. The microstructure, phase composition, microhardness and wear resistance of the laser cladding composite coatings were investigated by optical microscope, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and pin on disc wear test. The results show that the morphology of reinforced TiC homogeneously disperses in TiAl matrix and changes from dendritic TiC into short bar and particle shape with increasing the scanning rate. Also, the microhardness is enhanced by an increase in the scanning rate. The average microhardness of the composite coating under laser scanning rate of 600 mm min^-1 is 1·8 times of the substrate. The laser cladding composite coatings have better wear resistance than original TiAl alloy, and the wear mechanisms are discussed in detail.