The effect of hot extrusion on the microstructure and anti-corrosion performance of LDHs conversion coating on AZ91D magnesium alloy

Abstract In this study, the effect of hot extrusion on the microstructure and anti-corrosion performance of LDHs (layered double hydroxides) conversion coating on AZ91D magnesium alloy was investigated by means of microscopic observation and electrochemical measurement. After hot extrusion, the refinement and rearrangement of the β-Mg 17 Al 12 phase promotes the microgalvanic effect in the formation process, and the increase of dislocation density, twin, grain boundary and texture accelerates the dissolution rate of the Mg matrix. Due to microstructural differences, the electrochemical activity of various specimens in the formation process can be ranked as the increasing series: as-cast