The Effect of Rod-Shaped Long-Period Stacking Ordered Phases Evolution on Corrosion Behavior of Mg95.33Zn2Y2.67 Alloy 

Jingfeng Wang ^1,2,* , Weiyan Jiang ¹, Shengfeng Guo ^3,*, Yang Li ¹ and Yao Ma ¹ 

¹ National Engineering Research Center for Magnesium Alloys, College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China 

² State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China 

³ Faculty of Materials and Energy, Southwest University, Chongqing 400715, China 

 Abstract  

The morphology evolution of long-period stacking ordered (LPSO) phases on corrosion behavior of Mg95.33Zn2Y2.67 alloy is investigated systematically during as-cast, pre-extrusion heat-treated, as-extruded and post-extrusion heat-treated conditions. The second phases in the as-cast alloy are only LPSO phases with a few Y particles. The pre-extrusion heat treatment changed LPSO phases from blocks into a rudimentary rod shape with lamellar structure, subsequently into fine fragments by extrusion, and then into a regular rod shape with lamellar structure followed by post-extrusion heat treatment. Immersion tests and electrochemical measurements in 3.5 wt % NaCl solution reveal that the post-extrusion heat-treated alloy has the best corrosion resistance with the lowest corrosion rate. This is attributed to the rod-shaped LPSO phases, which could hinder corrosion proceeding, and result in corrosion orientated along the direction of rods and forming relatively dense long-strip corrosion products. Our findings demonstrate that the improved corrosion resistance of magnesium alloys with LPSO phases can be tailored effectively by the proceeding technology and post-heat treatment. 

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