Twinning and dynamic recrystallization of Mg-7Sn-3Zn alloy under high strain rate hot compression

In this study, we investigate the twinning behavior and dynamic recrystallization (DRX) of Mg-7Sn-3Zn alloy under a high strain rate (10 s(-1)) during hot compression deformation. At a relatively low temperature (300 degrees C) and high strain rate (10 s(-1)), the preferential occurrence of multiple {10 (1) over bar2}<10<(1)over bar>1> tension twin variant at the initial compressed stage is attributed to the Schmid factor (SF) criterion, and the following {10 (1) over bar2}<10<(1)over bar>1> tension twin variants nucleate because of the geometric compatibility factor m' of the ortho-position twin pair. Because of the growth and interaction between the ortho-position {10 (1) over bar2}<10<(1)over bar>1> tension twin pairs, the volume fraction of 60 degrees <10<(1)over bar>0> boundaries evidently increases. Moreover, as the logarithmic strain increases, the volume fraction of {10 (1) over bar2}<10<(1)over bar>1> tension twins and 60 degrees <10<(1)over bar>0> boundaries significantly decreases, and a few {10 (1) over bar1}<10<(1)over bar>2> compression twins and {10 (1) over bar2}-{10 (1) over bar1} double twins form. Then, twinning-induced dynamic recrystallization (TDRX) as a primary DRX mechanism occurs in {10 (1) over bar(1) over bar1}<10<(1)over bar>2> compression twins and {10 (1) over bar2}-{10 (1) over bar1} double twins. These results indicate that at a high temperature (400 degrees C) and 10 s(-1), certain {10 (1) over bar2}<10<(1)over bar>1> tension twins form during the early stage compression in accordance with the SF criterion, and discontinuous DRX (DDRX) occurs along the original grain boundaries because of the higher deformation temperature, which increases the nucleation rate and promotes the migration of grain boundaries. With the accumulation of logarithmic strain, continuous DRX (CDRX) occurs. The recrystallization grains consume the twin boundaries, which causes the {10 (1) over bar2}<10<(1)over bar>1> tension twins to merge. Under the same logarithmic strain, when the deformation temperature increases from 300 degrees C to 400 degrees C, the DRX process is significantly improved.

Automated summary

This study investigates the twinning behavior and dynamic recrystallization (DRX) of Mg-7Sn-3Zn alloy under high strain rate conditions. The results show that certain twinning mechanisms occur at different temperatures, influenced by factors such as Schmid factor and geometric compatibility. Additionally, the recrystallization process is significantly improved at higher temperatures, likely due to enhanced grain boundary migration and nucleation rate.