Optimizing microstructure and mechanical properties of biomedical Mg-Y-Zn-Mn alloy with LPSO phases by solution treatment plus equal-channel angular pressing

Long-period stacked ordered (LPSO) Mg-Y-Zn alloys have shown great medical prospects. To explore the impact of LPSO phase evolution on mechanical properties, a new biomedical Mg-2.2Y-1.1Zn-0.4Mn (wt.%) alloy prepared by solution treatment plus equal-channel angular pressing (ECAP) was systematically investigated. The results indicate that massive 18R LPSO networks along alpha-Mg grain boundaries are disintegrated during solution treatment of the as-cast alloy, whereas 14H lamellas are precipitated in alpha-Mg grains. Following a similar dispersion of 14H precipitated phases, the remnant 18R network phase was gradually extended, broken, and refined throughout the subsequent multi-pass ECAP process. The refined LPSO phases promote dynamic recrystallization (DRX) during the severe deformation process and improve mechanical properties of the obtained fine-grained alloy. After 773K solution treatment for 10h plus 693K ECAP for 12 passes, the biomedical alloy with co-existing 18R and 14H LSPO phases shows excellent mechanical properties with an ultimate tensile strength of 326.6 MPa and elongation of 14.5 percent. (C) 2021 The Author(s). Published by Elsevier B.V.