Surface Protection Effect of Diffusion Pack Cementation Process by Al-Si Powders with Chloride Activator on Magnesium and Its Alloys

Abstract

Diffusion pack coatings via Al-Si powders with an AlCl₃ chloride activator have been investigated in order to examine the surface protection effect on pure magnesium and magnesium alloys. Pure Magnesium and commercial AZ31 magnesium alloys have been subjected to diffusion coatings in an Al alloy powder for various time frames. When the pack coating was carried out at 823 K for 15 h, the Mg₁₇Al₁₂ layer has been successfully synthesized on the pure magnesium substrate. Similarly, a pack annealing at 823 K for 15 h showed a synthesized Mg-Al layer on the AZ31 magnesium alloy as a coating layer. Mechanisms for the surface layer formation are discussed together with growth kinetics and microstructural observations.