Influence of heat treatment and ECAP on the mechanical properties, microstructure, and corrosion behaviour of a micro alloyed magnesium

: This work explores Mg-Zn-Ca material, with novel grain size achieved through equal channel angular pressing (ECAP). Experimental studies indicate that the mechanical properties of the ECAP-treated alloy have been significantly improved compared to those of the initial alloys. Finite element analysis (FEA) was employed to simulate the process, confirming that the characteristic high-shear-strain bands responsible for grain refinement were successfully induced. The formation of MgCaSi and Ca 2 Mg 6 Zn 3 phases helped to improve the corrosion resistance behaviour of both heat-treated and ECAP-processed alloys. While its overall corrosion resistance was similar to that of the heat-treated alloy, the ECAP-processed alloy showed enhanced resistance to pitting corrosion. This improvement is due to a more uniform protective layer as corrosion product, microstructure homogenization, and finer grains produced during the ECAP process. The protective layers in phosphate-buffered saline (PBS) solution, primarily consisting of phosphates and carbonates, were analyzed using X-ray photoelectron spectroscopy (XPS). These findings suggest that the Mg-Zn-Ca alloy processed by ECAP is a promising candidate for biomedical application due to its superior mechanical and corrosion-resistant properties.