A novel Mg-5Al-2Zn-2Sn alloy with high strength-ductility synergy fabricated via simple hot rolling and annealing treatment

• Published in: Journal of alloys and compounds Vol. 869; p. 159308
• Main Authors: Ma, Chen-Yi, Xia, Nan, Wang, Cheng, Li, Mei-Xuan, Hua, Zhen-Ming, Ren, Ming-Wen, Wang, Hui-Yuan
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.07.2021; Elsevier BV
• Subjects: Alloys; Annealing; Annealing treatment; Ductility; Elongation; High strength alloys; Hot rolling; Magnesium base alloys; Mechanical properties; Mg-Al-Zn-Sn alloy; Microstructure; Precipitates; Room temperature; Tensile properties; Ultimate tensile strength; Yield strength; Mg-Al-Zn-Sn alloy; Microstructure; Hot rolling; Annealing treatment; Tensile properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.159308

•A high strength and ductility AZT522 alloy was developed to compete with AZ91 alloy.•The AZT522 alloy had much finer as-cast microstructure than AZ91 alloy.•The AZT522 alloy exhibited superior rolling formability to the AZ91 alloy.•The annealed AZT522 alloy showed higher strength and ductility than AZ91 alloy. A novel Mg-5.34Al-2.23Zn-1.73Sn (wt%, AZT522 for short) alloy with high strength-ductility synergy was designed and fabricated via simple hot rolling and annealing treatment to compete with the commonly used Mg-9Al-1Zn-0.2Mn (wt%, AZ91) alloy. Different from the coarse microstructure of the as-cast AZ91 alloy, the as-cast AZT522 alloy has much finer microstructure, which consists of finer dendrites and smaller second phase particles. Hot rolling was carried out on the solution-treated alloys to effectively refine the microstructure and improve the mechanical properties. The results suggest that the AZT522 alloy shows better rolling formability. Then, the hot-rolled AZT522 alloy was annealed at the optimized parameter, i.e., 225 °C/1.5 h, leading to uniform fine grains with an average size of ~2.3 µm and numerous near-spherical precipitates (Mg17Al12 and Mg2Sn) with a mean diameter of ~90 nm. Benefiting from the fine annealing microstructure, the novel AZT522 alloy finally exhibited high tensile properties at room temperature, i.e., ultimate tensile strength (UTS) of ~343 MPa, yield strength (YS) ~271 MPa, and elongation to failure (δf) ~16%, which is a much better combination of strength and ductility than the annealed AZ91 alloy. This novel AZT522 alloy may provide a new insight to develop commercial high strength and ductility Mg alloys.