Hetero-deformation induced strengthening and corrosion control of Mg-Li-Al/Pure Zn clad composites

In this study, Mg-Li-Al/Zn clad composites were fabricated via hot pressing using a lightweight, highly ductile Mg-Li-Al alloy and pure Zn, which exhibits appropriate degradation behavior, with the aim of developing next-generation biodegradable implant materials. The microstructure, mechanical properties, and corrosion behavior of the fabricated clad composites were comprehensively characterized. The bonding interface formed by hot pressing exhibited sound metallurgical integrity, free from macroscopic defects or the formation of brittle intermetallic compounds. Tensile tests revealed that the clad composites possessed an excellent balance of strength and ductility, which varied with the volume fraction of the constituent layers. Notably, the strength exhibited a positive deviation, exceeding the values predicted by the rule of mixtures (ROM). Electron backscatter diffraction (EBSD) analysis identified an elevation in kernel average misorientation (KAM) values within the soft Zn layer adjacent to the bonding interface. This finding indicates a high-density accumulation of geometrically necessary dislocations (GNDs) arising from strain incompatibility at the dissimilar interface. Consequently, it was determined that hetero-deformation induced (HDI) hardening, driven by this GND accumulation, is the primary mechanism responsible for the strength enhancement beyond theoretical predictions. Furthermore, electrochemical measurements demonstrated that the Zn layer exhibits a nobler corrosion potential and superior corrosion resistance compared to the LA141 layer. These results suggest that the deployment of Zn as a surface layer effectively suppresses the rapid degradation of the highly corrosion-susceptible Mg alloy core. • Hot-pressed Mg-Li-Al/Zn clad sheets exhibit a sound metallurgical interface. • Strength and ductility balance exceeds rule of mixtures predictions. • Hetero-deformation induced hardening governs the synergistic strengthening. • EBSD analysis confirms GND accumulation near the soft Zn layer interface. • Zn cladding effectively improves corrosion resistance of the Mg-Li-Al core.