The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al4Sr and Al2Y phases. The dynamic recrystallization (DRX) kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress–strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al4Sr phases and spheroidal Al2Y particles, which can accelerate the nucleation. The continuous Al4Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion.
Due to limited basal slips, the recrystallization of Mg–Zn-Nd-Zr alloys originated at grain boundaries with large orientation gradient based on strain-induced-boundary-migration nucleation mechanism. The primary driving force of the recrystallization was the distortion energy difference around grain boundaries. However, more non-basal slips occurred near the grain boundary at larger strain deformation, so that some dislocations of adjacent subgrain boundaries with less orientation difference transferred to other subgrain boundaries by means of dissociation and disassembly, which is called the subgrain boundary merging. Meanwhile, some ductile shear zones appeared surrounding the primary grain, which held multiple slip systems moving around the grain boundary, gave rise to larger orientation gradients and facilitated recrystallization grains growing.
19 June 2023 in Journal of Materials Research and Technology