Synergistic effect of Mn + Sc additions on the microstructure evolution and mechanical properties of Mg-Gd-Y-Mn-Sc alloy

• Published in: Journal of materials research and technology Vol. 21; pp. 3756 - 3766
• Main Authors: Yang, Zhao, Wang, Gang, Xu, Chao, Wang, Miao, Nakata, Taiki, Xu, Hongyu, Geng, Lin, Kamado, Shigeharu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2022; Elsevier
• Subjects: Ageing treatment; Mechanical properties; Mg-Gd-Y-Mn-Sc alloy; Microstructure; Precipitation; Mechanical properties; Precipitation; Ageing treatment; Mg-Gd-Y-Mn-Sc alloy; Microstructure
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2022.11.015

Mg-Gd-Y-Mn-Sc alloys with different Mn + Sc contents were prepared by hot extrusion and ageing treatment. The effect of Mn + Sc additions on the microstructures, tensile properties, and corresponding strengthening mechanisms of the as-extruded and peak-aged Mg-Gd-Y-Mn-Sc alloys were systematically investigated. Mn + Sc additions had outstanding grain refinement effect on the homogenized alloy and promoted the supersaturation of the Gd and Y atoms in α-Mg matrix, facilitating the dynamic recrystallization (DRX) and dynamic precipitation during hot extrusion. The DRX mainly occurs via discontinuous DRX (D-DRX) and continuous DRX (C-DRX) mechanisms. The as-extruded alloy with higher Mn + Sc contents exhibits better strength-ductility balance with a tensile yield strength of 337 MPa, ultimate tensile strength of 406 MPa and elongation to failure of 10.8%, which is mainly attributed to higher DRX fraction and denser dynamically precipitated particles. The Mn + Sc additions benefits the age-hardening response and notably improves the tensile yield strength to be 484 MPa for the peak-aged alloys by ageing precipitation and GB solute segregation, which is superior than previously reported Mg-RE-Mn alloys.