Microstructure evolution and mechanical properties of bulk nanocrystalline Zn−Cu−Sr−Li alloy processed by high-speed rolling

Nanocrystalline Zn−3Cu−0.2Sr− x Li ( x =0, 0.2, 0.4, wt.%) alloys were prepared via high-speed rolling to meet the urgent demand for high-performance alloys in the biomedical field. The high-speed rolling process generated numerous dislocations, providing sufficient driving force for recrystallization. The addition of Li promoted the formation of ε and β phases. These secondary phases provided abundant heterogeneous nucleation sites and a strong pinning effect, facilitating recrystallized grain nucleation while inhibiting its growth. The grain size of the alloy containing 0.4 wt.% Li was refined from 181.8 μm to 50 nm after rolling. The ultimate tensile strength, yield strength, and elongation of the rolled alloy containing 0.4 wt.% Li achieved 433.3 MPa, 389.2 MPa, and 15.2%, respectively. Compared to the as-cast Li-free alloy, 0.4Li alloy demonstrated a 173% increase in yield strength and a 591% improvement in elongation. Nanocrystalline strengthening was the dominant mechanism, contributing 70.4% to the total yield strength of the rolled Zn−3Cu−0.2Sr−0.4Li alloy.