Study on microstructure and properties of Ni-based alloy/Y2O3-deposited metals by laser cladding

Laser cladding of Ni-based alloy/Y₂O₃ (Yttrium Oxide) powder on 6061 aluminum alloy was carried out using 3 kW CW Nd:YAG laser to strengthen and improve hardness and corrosion resistance of substrate. Metal matrix composite composed of aluminum substrate, Ni-based alloy, refining and dispersion strengthening Y₂O₃, and particle hardening W, Cr was obtained. The microstructure and morphology, phase identification, element diffusion, and composition analysis of the Ni-based alloy/Y₂O₃-deposited metal and deposited metals/6061 aluminum substrate interface were examined using scanning electron microscopy (SEM), Electron Probe Micro-analyzer (EPMA) with energy-dispersive spectrometer (EDS) analysis. The micro-hardness distribution and corrosion-resistance property were investigated also. The results showed: (1) with the addition of Y₂O₃, more fine microstructures consisted of isometric crystal, white acicular crystal, and fringe crystal, primary phases were mainly Ni₃Al, NiAl, NiAl₃, W, α-Al, and Cr _x C. (2) Micro-hardness of deposited metals was 780–1100 HV_0.2 and distributed smoothly near interface. The corrosion rate of aluminum substrate was nearly twice that of deposited metals with addition of Y₂O₃.