Improved corrosion resistant and strength of a magnesium alloy using multi-directional forging (MDF)

Extruded Mg alloy (ZAXM4211) was subjected to multi-directional forging (MDF) at different temperatures from 180 to 300 °C. Microstructure was analyzed using optical microscope (OM), scanning electron microscope (SEM), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD) studies. Tensile and compression properties were evaluated and corrosion behavior was examined using electrochemical and immersion corrosion tests. It was found that the increase in MDF temperature decreased the yield strength due to an increase in the grain size. Furthermore, the corrosion rate was decreased as the MDF temperature was increased could be due to the dissolution of the second phases, which was further substantiated by the image analysis and scanning Kelvin probe force microscope (SKPFM) studies. The relationship between yield strength and grain size and furthermore, corrosion rate and second phases were quantitatively analyzed.