Microstructure and mechanical properties of a cast heat-resistant rare-earth magnesium alloy

China Foundry - Tập 20 - Trang 289-298 - 2023
Xiao-ping Zhu1, Jun-qing Yao2, Hai-long Wu3,4, Xin-wang Liu2, Hua Liu5, Zi-tian Fan2, Shu-lin Lü2, Kai Wang3,4, Zi-dong Wang1
1School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, China
2State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
3Dekai Intelligent Casting Co., Ltd., Zhuozhou, Hebei, China
4China Iron and Steel Research Institute Group, Beijing, China
5Guangdong Hongtu Wuhan Die-casting Co., Ltd., Wuhan, China

Tóm tắt

Microstructure, mechanical properties and phase transformation of a heat-resistant rare-earth (RE) Mg-16.1Gd-3.5Nd-0.38Zn-0.26Zr-0.15Y (wt.%) alloy were investigated. The as-cast alloy is composed of equiaxed α-Mg matrix, net-shaped Mg5RE and Zr-rich phases. According to aging hardening curves and tensile properties variation, the optimized condition of solution treatment at 520 °C for 8 h and subsequent aging at 204 °C for 12 h was selected. The continuous secondary Mg5RE phase predominantly formed at grain boundaries during solidification transforms to residual discontinuous β-Mg5RE phase and fine cuboid REH2 particles after heat treatment. The annealed alloy exhibits good comprehensive tensile property at 350 °C, with ultimate tensile strength of 153 MPa and elongation to fracture of 6.9%. Segregation of RE elements and eventually RE-rich precipitation at grain boundaries are responsible for the high strength at elevated temperature.

Tài liệu tham khảo

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