Abstract
Mg-8Zn-0.5Zr-0.5Gd alloy was prepared by high pressure solidification. Effect of high pressure on microstructure, micro-hardness and corrosion behavior in Hank's solution of the Mg-8Zn-0.5Zr-0.5Gd alloy were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffractometer (XRD). The results showed that, compared with the conventional solidification, high pressure solidification obviously refined the grain size of Mg-8Zn-0.5Zr-0.5Gd alloy. The grain size was refined from 200-300 μm to 100-200 μm and the secondary dendrite arm spacing reduced from 30-50 μm to 10-30 μm. Moreover, the solubility of Zn in the alloy increased and the amount and size of Mg-Zn-Gd phases significantly decreased. The micro-hardness of the alloy solidified under high pressure was improved significantly from 56.17 HV to 63.14 HV. The polarization resistance (Rp) of the alloy had a substantial increase in simulated body fluid, thus the corrosion rate was significantly reduced from 4.0 to 2.7 mm·year-1.