Impact of Extrusion, ECAP, and Annealing on the Microstructure, Mechanical Properties, and Biocorrosion Behavior of the ZX10 Magnesium Alloy

Magnesium alloys are increasingly recognized as promising materials for biomedical implants due to their low density, biocompatibility, and favorable mechanical properties. However, achieving a balance between mechanical strength and bio-corrosion resistance remains a critical challenge. This study evaluates the effects of three thermomechanical processing techniques — extrusion (EXT), Equal Channel Angular Pressing (ECAP), and ECAP followed by low-temperature annealing at 150°C for 10 hours (ECAP-A) — on the microstructure, mechanical properties, and bio-corrosion behavior of the ZX10 magnesium alloy. EXT resulted in a coarse, elongated grain structure, increased volume fraction of Mg2Ca particles, and moderate mechanical and corrosion performance. ECAP lowered the volume fraction of Mg2Ca particles and significantly refined the grain structure, and increased dislocation density, improving hardness by 80%, yield strength, and ductility. However, the corrosion rate doubled due to the high dislocation density. Post-ECAP annealing (ECAP-A) mitigated this limitation, reducing the corrosion rate to 1.50 mm/year while maintaining a high yield strength (>200 MPa). This improvement was driven by a uniform distribution of the Ca2Mg6Zn3 phase, a further reduction of the Mg2Ca phase, and decreased dislocation density. These findings demonstrate that ECAP, followed by annealing, optimally balances mechanical performance and bio-corrosion resistance, making the ZX10 magnesium alloy a promising candidate for biodegradable implant applications