Corrosion Behavior of Friction Extruded Magnesium Alloys: Grain Refinement and Particle Fragmentation Effect

The enhancement of corrosion resistance in conventional magnesium alloys across a spectrum of environmental conditions, from alkaline to acidic regimes, remains a pivotal requirement for their widespread industrial adoption. This study investigates the impact of Friction Extrusion (FE) on microstructural refinement and its consequent influence on the corrosion behavior of cast Mg and Mg-3Si alloys. FE treatment effectively refined the magnesium microstructure by diminishing grain size and eliminating microstructural twins. Additionally, it homogenized the distribution and fragmented the cathodic Mg₂Si particles in the Mg-3Si alloy. Both grain refinement and particle fragmentation markedly influenced the overall corrosion response, evident from the heightened cathodic kinetics observed in FE-processed samples. Time-resolved measurements of Mg²⁺ dissolution current, coupled with potentiodynamic polarization analyses, demonstrated an increased level of cathodically induced anodic dissolution in FE-processed Mg compared to the FE-treated Mg-3Si alloy. These experimental findings offer novel insights into the fundamental mechanisms governing corrosion resistance in magnesium alloys, underscoring the critical roles of solid-state processing techniques and initial alloy compositions in determining their corrosion behavior.