Effects of trace Ca addition on microstructure and mechanical properties of as-cast Mg-Sm-Gd-based alloy
(1. Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China;
2. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;
3. School of Mechanical and Automotive Engineering, Changchun Institute of Technology, Changchun 130012, China)
2. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;
3. School of Mechanical and Automotive Engineering, Changchun Institute of Technology, Changchun 130012, China)
Abstract: The effects of trace amounts of Ca on the microstructure and mechanical properties of as-cast Mg-Sm- Gd-Zn-Zr alloy were systematically investigated mainly by means of transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and tensile test. The results reveal that the dominant intermetallic compound in Mg-Sm-Gd-Zn-Zr alloy is Mg3RE phase with significant enrichment of Zn. The addition of Ca in Mg-Sm-Gd-Zn-Zr alloy can not only refine grains, but also promote the formation of Mg5RE phase and solute-enriched stacking faults (SESFs). The coherent interface indicates that Mg3RE phase can act as the nucleation site of Mg5RE phase. Finally, the decreased grain size and the formation of Mg5RE phase and SESFs in the Ca-modified alloy are beneficial to the enhancement of mechanical properties.
Key words: Mg-Sm-Gd alloy; Ca; microstructure characterization; mechanical properties; transmission electron microscopy (TEM)