Study of Corrosion Behavior of Mg-Gd Based Soluble Magnesium Alloys

In order to investigate the corrosion behavior of Mg-Gd based soluble magnesium alloy materials, two aspects, environmental factors and microstructural point of view, were discussed in this study respectively. Among them, the environmental factor aspect was carried out by immersion weight loss tests at different Cl- concentrations and different temperatures. In terms of microstructure, the influence of different initial tissue morphologies on the corrosion behavior of the alloy was mainly investigated, and the second phase Mg5Gd, prepared by melting, was subjected to immersion weight loss tests and electrochemical tests. The results show that the corrosion rate of the alloy increases with the increase of Cl- concentration and temperature, but the growth trend is not linear, in which the Cl- concentration of 1% to 3% and the temperature of 75 °C to 100 °C have a significant effect on the corrosion rate of the alloy, respectively; the dissolution rate of Mg-Gd-based soluble magnesium alloy after extrusion + perforation deformation was greatly improved from 8.37 mg/cm2/h in the as-cast state to 43.85 mg/cm2/h. Combined with the microstructure analysis, it is believed that the extrusion destroys the coarse reticulated second phase in the as-cast state organization, which reduces the corrosion-blocking network effect of the second phase; electrochemical tests showed that the second phase Mg5Gd formed after the addition of the rare earth element Gd had a high electrochemical activity.