Mechanical Properties and Corrosion Behavior of Hot Extruded Mg99.2Ca0.6Mn0.2 Alloy in SBF Solution

The tensile and compression properties of hot extruded Mg99.2Ca0.6Mn0.2 (at%) alloy were tested, and the cyclic polarization curves and impedance spectroscopy of the alloy soaked in SBF solutions with various pH values were measured by electrochemical method so that the corrosion behavior of the alloy can be evaluated and the experimental foundation for preparation of magnesium implant materials was provided. The results show that the tensile failure of the alloy appears to be characteristic of quasi-cleavage fracture. The tensile strength, yield strength, compressive strength and elongation are 279 MPa, 251 MPa, 330 MPa and 11% at room temperature, respectively. The pH value of the solution has prominent effect on corrosion behavior. As the pH value increases, the arc radius of impedance spectroscopy and corrosion potential increase remarkably, whereas the corrosion current density decreases, and thus the corrosion resistance of the alloy is strengthened. There is only one time constant which appears at low frequency in phase angle plot. The corrosion rate can be significantly reduced by increasing pH value of the solution. The instantaneous corrosion rates of the alloy immersed in the solutions with pH value of 7.2 and 10.0 are 4.1 mm/a and 0.2 mm/a, respectively.