Opposite Effects of Zn Addition on the Creep Resistance at Low and High Temperatures for As-Cast Mg-15Gd Alloy

Northwestern Polytechnic University (NPU) - School of Materials Science and Engineering; Northwestern Polytechnic University (NPU) - State Key Laboratory of Solidification Processing

Abstract

The effect of Zn addition on the mechanical properties in Mg-RE alloys has been controversial. In this study, the as-cast Mg-15Gd alloy was selected as a model system to illustrate the effect of Zn on the microstructures and creep properties. The results showed that the main strengthening phase transformed from β' in the Mg-15Gd alloy to long-period stacking ordered (LPSO) structure in the Mg-15Gd-1Zn alloy. At low temperatures (≤285 °C), when the creep mechanism was dislocation slip, the prismatic β' phase hindered the movement of dislocations, leading to better creep resistance of the Mg-15Gd alloy. On the contrary, at high temperatures (>285 °C) when the creep was controlled by dislocation climbing, the Mg-15Gd-1Zn alloy with lower stacking fault energy and basal LPSO phase showed better creep resistance. These findings inspire us to design the composition of Mg-RE alloys in different service environments for better performance.

Keywords: Mg-Gd-Zn alloys, microstructures, tensile creep properties, creep mechanisms

Suggested Citation: Suggested Citation

Ouyang, Shuxia and Yang, Guangyu and Chen, Cheng and Bai, Tong and Qin, He and Wang, Chunhui and Zhang, Lei and Jie, Wanqi, Opposite Effects of Zn Addition on the Creep Resistance at Low and High Temperatures for As-Cast Mg-15Gd Alloy. Available at SSRN: https://ssrn.com/abstract=3990173 or http://dx.doi.org/10.2139/ssrn.3990173