Influence of heat treatment on corrosion behavior of hot rolled Mg5Gd alloys
(1. Center for Marine Materials Corrosion and Protection, College of Materials, Xiamen University, Xiamen 361005, China;
2. State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China;
3. School of Engineering, The University of Queensland, St. Lucia, Qld 4072, Australia)
2. State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China;
3. School of Engineering, The University of Queensland, St. Lucia, Qld 4072, Australia)
Abstract: The influence of heat treatment on the corrosion behavior of rolled Mg5Gd alloys in 3.5 wt.% NaCl solution saturated with Mg(OH)2 was characterized by immersion test, electrochemical test, scanning electrochemical microscopy (SECM) and corrosion morphology analysis in order to improve the corrosion resistance of Mg alloys. The results showed that solution treatment reduced the corrosion rate of the Mg5Gd significantly, resulting in relatively uniform corrosion and shallow corrosion cavities due to the dissolution of Cd-containing particles. The following aging process could further decrease the corrosion rate. Precipitation of nano-sized Cd-containing particles did not cause apparent micro-galvanic corrosion, which could be attributed to the formation of a protective corrosion product film fully covering the particles.
Key words: magnesium alloy; rare earth; corrosion resistance; microstructure; heat treatment