Mechanical and Corrosion Properties of AZ31 Mg Alloy Processed by Equal-Channel Angular Pressing and Aging

Magnesium (Mg) has a good biocompatibility and thus a potential candidate for medical implants. However, the major drawback of Mg alloys consists of their fast corrosion rate, especially in the physiological pH 7.4environment thereby losing their mechanical integrity before the tissues have sufficient time to heal. Nevertheless, the use of Mg alloys as biodegradable implants has been promising, however their corrosion resistance should be enhanced. It has been known that equal-channel angular pressing (ECAP) process significantly affects the mechanical properties of Mg alloys but as the tensile strength rises, the corrosion performance deteriorates. Additionally, the secondary phase influences the corrosion resistance of magnesium-aluminum based alloys. The second-phase plays dual roles that depend on the amount and distribution of this phase. Therefore, in this study, we attempted to investigate the effect of grain refinement and second-phase redistribution on corrosion behavior and mechanical properties of AZ31 Mg alloy by changing the condition of ECAP process and subsequent aging. Per the optical microstructure observation, a fine and homogeneous second-phase microstructure appears to be a better anti-corrosion barrier, hence enhances the corrosion resistance of the alloy.