The microstructure and mechanical behavior during 100 °C warm rolling of the high-Zn-content Al80Zn14Li2Mg2Cu2 alloy were investigated. The alloy plate was warm-rolled to reductions of 40%, 60%, and 80%. Hardness and tensile strength decreased continuously with increased rolling up to 60%, demonstrating work softening, followed by a slight increase at 80% reduction, indicating work hardening. Systematic characterization revealed that this non-monotonic mechanical response arises from a competition between particle-stimulated nucleation (PSN)-assisted recrystallization and dislocation-driven hardening. The multi-scale intermetallic particles in this alloy play a dual role: coarse Al5CuLi3 particles generate high-strain particle deformation zones (PDZs) that serve as potent PSN sites, while fine nano particles pin the recrystallized grain boundaries and restrict their growth. The unusually low PSN activation temperature is attributed to the synergistic effects of the high PDZ storage energy and the progressive subgrain rotation mechanism within the PDZ. The ability to control PSN via micro- and nano-scale intermetallics presents a viable pathway for achieving grain refinement in Al-based alloys and enhancing the machinability of high-Zn-content Al alloys.
Li et al. (Fri,) studied this question.