Abstract:

Al-Si alloy coatings were prepared on AZ91HP magnesium alloy by broad-beam laser cladding; the influences of the powers on the microstructure and properties of the coatings were discussed. It was found that the microstructure of the coatings at the powers of 3 and 3.5kW was characterized by Mg₂Si dendrites, and needle-like Mg₂Al₃(hcp) dispersing in the Mg₁₇Al₁₂ matrix, whereas the coating at the power of 2.5 kW was composed of the petal-like Mg₂Al₃ (fcc) as well as the needle-like Mg₂Al₃(hcp). The coating at the power of 4 kW appeared as α-Mg solid solution and Mg₂Si, Mg₁₇Al₁₂, as well as Mg₂Al₃ (hcp). The coatings with the powers of 3 and 3.5　kW exhibited higher microhardness and better wear resistance because of more Mg₂Si and Mg₁₇Al₁₂. However, the coating at the power of 2.5 kW displayed better corrosion resistance.

Key words: Magnesium alloy, Al-Si alloy, Laser cladding, Laser power