Mechanical and corrosion properties of biodegradable Mg-2Mn-0.3Ca alloy with different grain structure: orientation and size

Abstract

The application of magnesium alloys in bone implants, cardiovascular stents and other devices in the field of biomaterials has been widely concerned. In this study, the microstructure and mechanical properties of Mg-2Mn-0.3Ca bar were investigated by the optical microscopy, scanning electron microscopy and universal material testing machine. The corrosion behaviors were carried out by hydrogen evolution, electrochemical tests and immersion tests in a simulated body fluid (SBF). The results show that the yield strength (YS) and ultimate tensile strength (UTS) of the extruded Mg-2Mn-0.3Ca alloy are 277 MPa and 285 MPa, respectively, mainly due to the effects of grain size and grain orientation. In the direction parallel to the extrusion direction (ED), the elongation (EL) of the alloy after heat treatment is increased by 357%, which is due to the random distribution of the grain orientation of the alloy after heat treatment, and the Schmidt factor is increased, (0001) < 11–20 > basal slip is more likely to be activated. At the initial stage of corrosion, bimodal grain structure is more prone to corrosion than equiaxed grain structure, and the final corrosion resistance is determined by grain orientation. Grain orientation has a more significant effect on the corrosion behavior of bars than grain size.