Processes and properties of liquid aluminized coating on AZ31 magnesium alloy

Liquid diffusion technology was used to aluminize on the surface of AZ31 magnesium alloy. The hypereutectic aluminized coating was obtained. The forming mechanism and properties of aluminized coating were studied by analyzing the component, phase state, nanoindentation hardness and corrosion resistance. The results show that a solidification-melting process occurs on the surface of AZ31 magnesium alloy when it is aluminized at 480°C. Mg₁₇Al₁₂ and Mg-Al supersaturated solid solution exist in the aluminized coating, and the coating nanoindentation hardness is about 3 times higher than that of AZ31 magnesium matrix, at the same time the corrosion resistance is improved obviously. Aluminizing in liquid phase may improve the diffusion velocity but up-and-down surface is formed due to surface solidification shrinkage from liquid phase, which can be controlled by reducing the cooling velocity.