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

• DOI: 10.1016/j.corsci.2019.108419
• Publication Date: 2019-12-30T11:14:54Z
• Authors: Siqi Yin; Wenchao Duan; Wenhong Liu; Liang Wu; Jiamin Yu; Zilong Zhao; Min Liu; Ping Wang; Jianzhong Cui; Zhiqiang Zhang
• Keywords: Volta potential; Galvanic cell; Immersion; Texture (cosmology)

Abstract 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} texture components.