Effect of Rare Earth on the Microstructure and Tribological Properties of Laser Cladding Ni-Based Coatings on 6063 Al

Ni-Based alloy coatings with different rare-earth oxides (La₂O₃, Y₂O₃, CeO₂) were prepared on the surface of 6063 aluminum alloy by using laser cladding. The effects of rare earth oxides on the microstructures,phase structures,microhardness and tribological properties of laser cladding Ni-Based alloy coatings on 6063 Al alloys were investigated by means of X-ray diffraction,scanning electron microscopy,micro-hardness tester,friction and wear testing machine. The results show that the main phases of the cladding layers with different contents were β-NiAl (Cr) and a small amount of Al₃Ni,AlNi₃ and Al. La₂O₃+Ni60 cladding layer contained rare earth compound Al₄La. Y₂O₃+Ni60 cladding layer contained YAl₃,AlNiY,Ni₁₇Y₂,and CeO₂+Ni60 cladding layer detected CeNi₅,Ce₃Ni₆Si₂ in the structures. The Ni60 cladding layers with addition of rare earth oxides exhibited uniform distribution of dendrites,no porosity,and more refined grains than Ni60 cladding layer without rare earth oxides. The increment of microhardness of Ni60 cladding layer was HV100~300 in the presence of rare earth oxides. And the hardness profile showed a mild transition in comparison with the cladding layer without rare earth oxides. The collapse damage of worn surface of Ni60 cladding layer was alleviated in the presence of rare earth oxides. The depth and width of wear track were greatly reduced and wear volumes were reduced by one order of magnitude. The friction coefficients were reduced.The cladding layers with addition of La₂O₃,CeO₂ had the lowest wear volume,and therefore the best wear resistance.