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 microhardness 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, a-Al, and CrxC. (2) Micro-hardness of deposited metals was 780– 1100 HV0.2 and distributed smoothly near interface. The corrosion rate of aluminum substrate was nearly twice that of deposited metals with addition of Y2O3