Interplay between Al-RE particles and twins: Strain gradient-driven twin boundary breakthrough of static recrystallized grains

The AZ31-0.9Nd-0.3Y alloy exhibits a uniform distribution of Al-RE particles at the grain scale, with Al 2 RE present within grains and Al 11 RE 3 located at grain boundaries (GBs). Using quasi‑in‑situ electron backscatter diffraction, this study investigated the underlying static recrystallization (SRX) mechanisms based on this distribution, with particular attention to the interplay between particle-stimulated nucleation (PSN) and twin‑induced SRX. The results demonstrated that grain-interior Al 2 RE particles acted as anchoring sites for dislocations, inducing particle deformation zones (PDZs) that activated the PSN mechanism and accelerated SRX nucleation within grains. When PDZs were adjacent to twin-induced SRX grains, the strain gradient established between them drove these grains to break through twin boundaries and survive the subsequent competitive grain coarsening. Meanwhile, the PSN triggered by Al 11 RE 3 particles generated randomly oriented SRX grains in GB regions and simultaneously accelerated SRX there. The activation of various SRX mechanisms and their interplay facilitated the nucleation of SRX grains via both intragranular and intergranular pathways. These fresh grains grew in both outward and inward directions, displaying a characteristic “face-to-face” development that consumed the parent grains from opposing sides. The interplay between the in-situ formed hard particles and twins would offer a promising way of accelerating SRX kinetics and weakening texture.