Improvement of corrosion resistance of pure magnesium via vacuum pack treatment

An aluminized coating on pure magnesium was conducted by vacuum pack aluminizing in order to improve its corrosion resistance. XRD and SEM/EDS analysis show that the alloying coating could be divided into two layers: the inner layer is mainly composed of beta-Mg17Al12 phase and the outer layer is mainly composed of alpha-Al. This coating is different from that obtained by diffusion alloying under protective atmosphere in its structure and phase constituents. A visible transition layer of aluminum in magnesium was found between the alloying layer and the magnesium substrate. The electrochemical testing results showed that the corrosion resistance of Mg was significantly improved due to the formation of the Al-rich layer and the large quantity Of beta-Mg17Al12 on the surface. The bonding between the alloying layer and the substrate is metallurgical, and the micro-hardness of this layer is increased significantly. (c) 2007 Elsevier B.V. All rights reserved.