Available online 11 January 2023
Abstract
Zn addition to Mg alloys activates non-basal slip or twinning with
solute softening effects. On the other hand, the effects of the Zn
solute on the macroscopic dislocation behavior and dynamic
recrystallization are not completely understood. Moreover, it is unclear
if <c+a> slip can be affected by changes in the c/a ratio of
solute atoms. This study was conducted to understand the solute
strengthening of Zn addition and its effects on the dislocation
characteristics and dynamic recrystallization. A hot torsion test was
performed on both AM30 and AZ31 alloys up to a high strain to
investigate the Zn solute effect on the dislocation characteristics and
dynamic recrystallization. The dislocation components of the hot
torsioned alloys were evaluated by X-ray line profile analysis and electron backscatter diffraction.
The results showed that the Zn solutes slightly accelerate strain
accumulation at the initial stages of hot deformation, which accelerated
recrystallization at high strain. The dislocation characteristics were
changed dynamically by Zn addition: fortified <c+a>-type slip,
dislocation arrangement and strain anisotropy parameters. The most
important point was that the dislocation characteristics were changed
dramatically at the critical strain for recrystallization and high
strain regions. The addition of Zn also acted greatly in these strain
areas. This indicates that the rapid formation of <c+a>-type slip
at the serrated grain boundaries occurs at the initiation of dynamic
recrystallization and the increase in the grain triple junction because
grain refinement has a great influence on the dislocation
characteristics at high strain.
Keywords