Abstract
Laser cladding of the Al₃Ti+TiC+(Ni-coated WC) pre-placed powders on titanium alloy can form the Ti₃Al/Al₃Ti matrix composite coating, which improves the surface performance of the substrate. With addition of nano-Y2O3, this composite coating exhibited a finer microstructure. In this study, the Al₃Ti+TiC+(Ni-coated WC)+nano-Y₂O₃ laser-cladded coatings have been researched by means of X-ray diffraction and scanning electron microscope. The function of nano-Y₂O₃ acted as the heterogeneous nuclei, and the growth of the grains was hindered by Y₂O₃ and Y. Y₂O₃ can also decrease the temperature of the molten pool. Thus, the probability that grains traverse potential barrier decreased, leads to more stability of the grains.

Key words
coatings, rare earth compounds, laser cladding, intermetallics, diffusion

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