Effect of Hydrostatic Pressure on LPSO Kinking and Microstructure Evolution of Mg–11Gd–4Y–2Zn–0.5Zr Alloy

Abstract

Two different kinds of hot compressions, namely normal-compression and can-compression, were performed on the Mg–11Gd–4Y–2Zn–0.5Zr alloy, featured with long period stacking ordered (LPSO) phase. The kinking behavior of LPSO phase and microstructure evolution was investigated to clarify the effect of levels of imposed hydrostatic pressure. The results suggest that the LPSO phases including both the intragranular 14H-LPSO phase and intergranular 18R-LPSO phase suffer severe kinking behavior under higher hydrostatic pressure induced by can-compression, which is firstly characterized with more kinking times and smaller relative kinking width. The main reason for such enhanced LPSO kinking during can-compression may be mainly ascribed to the higher dislocation density under a higher level of hydrostatic pressure. Meanwhile, a competitive relationship between the kink behaviors of intergranular 18R-LPSO phase and intragranular 14H-LPSO phase was observed. That is, the intergranular 18R-LPSO phase only kinks obviously on the condition that the surrounded intragranular 14H-LPSO phase scarcely kinks. In contrast to the distinctive kinking of LPSO phase, the dynamic recrystallization (DRX) mechanism shows less dependence on the hydrostatic pressure. Resultantly, similar DRX fractions and crystallographic texture were attained for two compression processes owing to the similar operation of deformation mode.