Microstructure evolution and mechanical properties of nanostructured bioabsorbable Mg-1Ca alloy processed by high-pressure torsion

This study analyzes the effects of High-Pressure Torsion (HPT) processing for N = 1 and N = 10 revolutions on the microstructure and mechanical properties of the Mg-1Ca alloy. X-ray diffraction analysis reveals changes in grain orientation with HPT processing, with prismatic and pyramidal slip systems activated with the increase of the number of revolutions of HPT. Grain refinement was observed from 6 µm in the as-extruded state to 2 µm after HPT processing for N = 10 revolutions, by optical microscopy and electron backscatter diffraction analyses. Correspondingly, average microhardness increases from 58 HV in the as-extruded condition to 62 HV. Additionally, ultimate tensile strength improves from 186 to 199 MPa, while ductility increases from 11 to 30% elongation to failure. This improvement in mechanical properties is attributed to grain refinement and Mg₂Ca dispersion in the Mg matrix by HPT.