Achieving high strength and excellent ductility in a Zn-3Cu-1Mg alloy through minor Nd addition and multi-pass ECAP

Nd element has been extensively investigated in biodegradable magnesium alloys due to its superior strengthening effect and biocompatibility. However, the role of Nd in biodegradable zinc alloys remains poorly understood. This work elucidates the impact of Nd microalloying (0.3 wt%) on Zn-3Cu-1Mg alloy processed via multi-pass equal channel angular pressing (ECAP). The as-cast alloy exhibited a composite microstructure comprising η-Zn solid solution, CuZn 5 phase, lamellar η-Zn/Mg 2 Zn 11 eutectic, and petaloid NdZn 11 particles. 8 pass (8 P) and 12 pass (12 P) ECAP processing induced severe plastic deformation in the alloy, resulting in a refined grain structure through dynamic recrystallization. However, the shape and size of the petal-like NdZn 11 phase remain largely unchanged, despite the development of numerous cracks within them. The alloy subjected to 12 P ECAP exhibits exceptional strength-ductility synergy, with yield strength (352 MPa), ultimate tensile strength (402 MPa), and elongation (31.7%)—a mechanical profile which not only meet the performance requirements for degradable metals but also surpass those of existing RE-containing zinc alloys. The significant improvement in strength is attributed to microstructural refinement and heterogeneous deformation strengthening from the alternating arrangement of soft CuZn 5 layers and hard eutectic layers. The extensive cracking within the petal-like NdZn 11 phase facilitates energy absorption and dissipation during deformation, thereby delaying crack propagation and enhancing the alloy's ductility. This study elucidates the evolution mechanisms of the NdZn 11 phase, providing a theoretical foundation for engineering high-performance zinc alloys through rare earth element alloying. • The Zn-3Cu-1Mg-0.3Nd alloy subjected to 12-pass ECAP achieves an exceptional strength-ductility synergy. • The superior performance stems from pronounced grain refinement and the unique role of petal-like NdZn 11 particles. • Cracking within NdZn 11 particles enhances ductility by promoting energy absorption and dissipation during tensile.