Effects of Zn content on surface deformability and corrosion resistance of MgZnMnCa alloys

The effects of the Zn content on the mechanical and corrosion properties of MgZnMnCa alloys were investigated. The results revealed that with increasing Zn content up to 4 wt.%, the Mg-4Zn-0.2Mn-0.2Ca (wt.%) alloy after solution treatment at 400 degrees C for 24 h (ZM40-S) exhibited a volume fraction of 1.56 +/- 0.05 (vol.%) of secondary phases with an average grain size of 83.6 +/- 1.6 mu m. This alloy in the at-cast condition exhibited indentation hardness (H-it) of 657.1 +/- 17.8 MPa, which increased to 723.5 +/- 29.8 MPa after solution treatments. In addition, the alloy also exhibited a Vickers hardness value of 66.8 +/- 2.7 HV and an elastic modulus of 33.8 +/- 0.6 GPa, close to the values for human bone. Further, the corrosion properties of this alloy were analyzed: it exhibited a cathodic polarization curve attributed to a hydrogen evolution reaction and an anodic curve corresponding to a passivation tendency, indicating the formation of an oxide layer at the surface; further, its corrosion rate was 0.23 mm/year.