Microstructure and mechanical properties of low-temperature wrought-processed Mg–Y–Zn alloy containing LPSO phase

Abstract

The effect of process temperature on microstructure and mechanical properties was investigated using Mg–4at%Y–2at%Zn alloy produced by caliber rolling at temperatures of 373 K and 748 K. Caliber rolled bars were successfully fabricated with the introduction of deformation kink bands in the long periodic stacking ordered (LPSO) structure, regardless of rolling temperature. Microstructural observations showed that the alloy rolled at 748 K had the same microstructural features as previously reported wrought-processed magnesium alloys that contained the LPSO phase. In contrast, the alloy rolled at the lower temperature (373 K) had a high density of residual strains and deformation twins, as well as deformation kink bands. These microstructural features affected the mechanical properties; the alloy rolled at 373 K had higher properties of strength and hardness compared with those of the alloy produced at 748 K. However, the lower-temperature rolled alloy showed a decrease in compressibility, due to the existence of micro-cracks. Three-dimensional microstructural observation revealed that such defects were unlikely to be present in deformation kink bands and at the interface between kink bands and LPSO/α-Mg phases.