Zn-0.8Mn alloy for degradable structural applications: Hot compression behaviors, four dynamic recrystallization mechanisms, and better elevated-temperature strength

Environmentally degradable Zn-0.8Mn alloy is highly ductile, which lays the foundation for developing high-performance Zn-Mn-based alloys. However, not only constitutive equation of this alloy is unknown, but also its dynamic recrystallization (DRX) behavior is unclear, which makes optimization of hot processing parameters of this alloy almost dependent on trial-and-error. This work aims to tackle these problems. The constitutive equation was deduced to be (epsilon) over dot = 1.38 x 10(12) x [sinh (0.009 sigma)](8)exp(-135150/RT). A processing map of the alloy was obtained for the first time, which shows that it has excellent hot formability with narrow instability zones. At a final true strain of 0.8, the volume fraction of DRX grains increased from 37% to 79% with temperature increasing from 150 degrees C to 350 degrees C and strain rate decreasing from 10 s(-1) to 10(-3) s(-1). Discontinuous DRX (DDRX), continuous DRX (CDRX), twinning-induced DRX (TDRX), and particle stimulated nucleation (PSN) were activated during hot compressions. DDRX was always the main mechanism. TDRX was completely suppressed at 300 degrees C and above. PSN arose from dispersed MnZn13 particles. Furthermore, Zn-0.8Mn alloy exhibited elevated-temperature strengths better than pure Zn and Zn-Al-based alloys. At 300 degrees C and 0.1 s(-1), its peak stress was 1.8 times of pure Zn, owing to MnZn13 particles of 277 +/- 79 nm impeding the motion of grain boundaries and dislocations. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.