Differences between the strain accommodation in the tensile vs compressive regions of a dilute Mg-Zn-Ca alloy subjected to cyclic four-point bending

This study endeavoured to achieve a comprehensive understanding of the deformation mechanisms in the regions under tension and compression of a dilute, biodegradable Mg-Zn-Ca alloy subjected to 21 cycles of four-point bending. The alloy with the thickness to grain size ratio (t/D) of 100 was prepared using hot-rolling followed by heat treatment, and microstructural characterisation was performed utilising quasi-in-situ electron backscattered diffraction (EBSD) analysis. Analysis: of the evolution of the EBSD maps revealed that strain is mainly accommodated by assisting extension twins at the compressive region throughout the 21 cycles of bending. This domination resulted in work-hardening and the prevalence of extension twin variants with lower Schmid factor. At higher strains where extension twins did not play their assisting role in the tensile region, the formation of low-angle grain boundaries was found effective in postponing crack nucleation.