Effects of reduced extrusion temperature on microstructure and mechanical properties of Mg-6Zn-0.5Zr alloy

Improving the strength of the commercial ZK60 alloys plays a key role in promoting their wide applications. In this work, a ZK60 alloy was prepared by conventional direct extrusion at an obviously reduced temperature of 180 & DEG;C. Compared with ZK60 alloys directly extruded at high temperatures (>300 & DEG;C), the studied alloy has finer dynamic recrystallized (DRXed) grains with the average size of -1.7 lm, stronger typical fiber texture and more profuse lath-like sub-grains. In addition, the ultra-low extrusion temperature increased dynamic precipitates (rod-like Mg4Zn7 and MgZn2) in DRXed grains. After aging, a great many of nanosized precipitates formed in both DRXed grains and non-recrystallized grains, and relatively coarse MgZn2 particles precipitated on sub-grain boundaries. As a result, the aged ZK60 alloy exhibit significantly high ultimate compressive strength of -675 MPa on the basis of high yield strength of -310 MPa, indicating a significant strain hardening capability. Meanwhile, it has excellent strengthductility balance and a weakened tension-compression yield strength asymmetry under owning a high TYS in order of -400 MPa.& COPY; 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).