Influence of specific second phases on corrosion behaviors of Mg-Zn-Gd-Zr alloys

• Published in: Corrosion science Vol. 166; p. 108419
• Main Authors: Yin, Siqi, Duan, Wenchao, Liu, Wenhong, Wu, Liang, Yu, Jiamin, Zhao, Zilong, Liu, Min, Wang, Ping, Cui, Jianzhong, Zhang, Zhiqiang
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 15.04.2020; Elsevier BV
• Subjects: A. Magnesium; B. EIS; B. Weight loss; C. Anodic dissolution; C. Pitting corrosion; Continuous extrusion; Corrosion; Corrosion effects; Corrosion mechanisms; Corrosion resistance; Corrosion resistant alloys; Gadolinium; Galvanic corrosion; Immersion tests (corrosion); Magnesium; Phases; Pressure casting; Submerging; Ternary systems; Uniform attack (corrosion); Zinc; Zirconium base alloys; A. Magnesium; C. Pitting corrosion; B. EIS; C. Anodic dissolution; B. Weight loss
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2019.108419

[Display omitted] •A comparatively considerable corrosion resistance is achieved in extruded Mg-3Zn-11Gd-0.6Zr alloy.•Lower potential differences between Mg-Zn-Gd ternary phases and Mg matrix are beneficial to corrosion behavior.•A wide distribution of compact X-phase lamella acts as corrosion barrier during corrosion.•X-phase could act as an anode during micro-galvanic corrosion with W-phase. The corrosion behavior and mechanism of as-cast and as-extruded Mg-Zn-Gd-Zr alloys with specific ternary phases are investigated using scanning electron microscope (SEM), scanning Kelvin probe force microscope (SKPFM), immersion and electrochemical tests. Lamellar X-Mg12GdZn, net-like W-Mg3Gd2Zn3 and strip-like I-Mg3Zn6Gd phases form successively. The eutectic W-phase owns the highest potential difference of 120 mV with Mg matrix, accelerating micro-galvanic corrosion. Continuously distributed and undersized I-phase leads to uniform corrosion. The as-extruded Mg-3Zn-11Gd-0.6 Zr alloy exhibits superior corrosion resistance, due to the relatively low potential difference between X-phase and matrix, the corrosion barrier effect and typical {0002} <10−10> texture components.