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

摘要

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 degrees C/1.5 h, leading to uniform fine grains with an average size of similar to 2.3 mu m and numerous near-spherical precipitates (Mg17Al12 and Mg2Sn) with a mean diameter of similar to 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 similar to 343 MPa, yield strength (YS) similar to 271 MPa, and elongation to failure (df) similar to 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. (C) 2021 Elsevier B.V. All rights reserved.