Effect of Y2O3 on the Wear and Corrosion Resistance of WC Reinforced Fe-Mn-Si Shape Memory Alloy (SMA) Composite Coatings Developed by Laser Cladding

Fe-Mn-Si/WC/Y2O3 composite coatings were prepared by laser cladding on the surface 304 stainless steel. The microstructure, phase composition, microhardness, and wear resistance as well as corrosion resistance of the composite coating were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness tester, friction wear tester and electrochemical workstation. The results show that WC is completely decomposed due to the high laser energy density and presents as in situ Fe6W6C phase and solid-solved in the coating. Microstructure of the coating consists of planar crystal, cell crystal, dendrites and equiaxed crystal. The wear resistance of the composite coating is simultaneously enhanced by solid solution strengthening, dispersion strengthening and the stress self-accommodation characteristic of Fe-Mn-Si shape memory alloy (SMA). The addition of Y2O3 makes the surface potential of the composite coating uniform, purifies the grain boundary and improves the corrosion resistance of the composite coating. When the content of Y2O3 is 0.8 wt. %, the wear resistance and corrosion resistance of the coating are optimal.