The effect of solid diffusion surface alloying on properties of ZM5 magnesium alloy

In this research, solid diffusion process was used to form a diffusion alloying layer on the surface of ZM5 magnesium alloy to improve corrosion and wear resistance. It is shown that the solid diffusion layer was mainly composed of Mg-Al-Zn intermetallic compounds and Mg-Al-Zn solid solution transition zone that had more Zn and Al elements than untreated ZM5 magnesium substrate. The continued immersion test in 3% NaCl solution displayed that the diffusion-treated specimen had better corrosion resistance compared to the untreated ZM5 specimen. The polarization test indicated that the Mg-Al-Zn intermetallic compounds of the diffusion alloying layer were an effective corrosion barrier to decrease the corrosion rate for ZM5 magnesium alloy when exposed to 3% NaCl solutions. In addition, the microhardness values of the Mg-Al-Zn intermetallic compounds were much higher than those of the substrate and this would greatly contribute to the enhancement of wear resistance.