Experimental Study of Nano-Al<sub>2</sub>O<sub>3</sub> Particles Reinforced Fe-Based Composite Coating Made by Laser Cladding

The experiment of laser cladding on the surface of Cr12 mold steel was made. Ni-coated nano-Al 2 O 3 particles powder was used as cladding material. The microstructure and hardness of laser cladding layer were tested. The research showed that the compact cladding layer without crack, gas hole and other defects could be made by laser cladding. The cladding layer was made up of three phases, Fe-Ni solid solution, Fe-Cr solid solution and nano-Al 2 O 3 particle. nano-Al 2 O 3 particles enhanced the inhomogeneous nucleation of Fe-based alloy, refined the crystal grains and strengthened the mechanical properties of cladding layer. The average hardness of cladding zone was 900 HV0.2 which was 2.2 times higher than that of substrate.