Abstract:In this paper, laser cladding of Al-Si/Al2O3 powders was applied on a Mg-Nd-Zn-Zr magnesium rare earth alloy, and the microstructure, phase components and properties of the clad layers were carefully characterized. X ray diffraction (XRD) analyses and scanning electron microscope (SEM) observations show that the clad layer is mainly consisted of α-Mg, Mg2Si, Mg12Nd and Al3.21Si0.47 or Mg17Al12 phases. However, Al2O3 particles agglomerate at the bottom of the clad layer close to the melt-substrate interface. The cross section microhardness tests reveal that the maximum hardness of the clad layer ranges from 309HV to 475HV, about 5 to 8 times higher than that of the Mg-Nd-Zn-Zr alloy (55HV) substrate. Such an increased hardness is attributed to the grain refinement, the solution strengthening, the formation of hardening phases and the dispersion strengthening from oxide particles. According to the potentiodynamic polarization measurements carried out in the 3.5wt% NaCl water solution, the corrosion potential of the alloy increased after laser cladding, while the corrosion current density decreased from 1.683×10-4(A/cm2)for the Mg alloy substrate to 0.843×10-5(A/cm2)for the laser clad alloy. Therefore, the corrosion resistance of Mg-Nd-Zn-Zr alloy can also be significantly improved by laser cladding with Al-Si/Al2O3 powders.