Effect of homogenizing and extrusion on microstructure and corrosion resistance of Mg-Hg-Ga Alloy

The microstructures of Mg-Hg-Ga alloy modified by homogenizing and hot extrusion were investigated by optical microscope, XRD and EBSD. The influence of homogenizing and hot extrusion on the corrosion behavior of Mg-Hg-Ga alloy was examined by hydrogen generation tests, potentiodynamic polarization, galvanostatic tests, impedance spectra (EIS) tests and current efficiency tests. The results show that the amount of second phase Mg2Hg significantly reduces after homogenizing. The hot extrusion promotes the dynamic recrystallization and refines the grains of Mg-Hg-Ga alloy, and the {0001} basal texture forms in the hot extruded alloy. The homogenizing promotes the corrosion resistance and anode efficiency of alloy and reduces the electrochemical activity of alloy. The hot extrusion improves the electrochemical activity, anode efficiency and reduces the corrosion resistance at the same time. The extruded alloy performs the most negative mean potential of -1.841 V(vs SCE), the largest hydrogen generation rate corrosion current density are 4.13 mL/(cm2·h) and 1.010 mA/cm2, respectively. The hydrogen generation rate and the corrosion current of the homogenized alloy are the smallest, which are 1.75 mL/(m2∙h-1) and 0.241 mA/cm2, respectively. The anode efficiency increases from 53.68% of as-cast alloy to 66.63% of extrusion alloy. © 2017, Science Press. All right reserved.