Corrosion behaviour of bulk ultra-fine grained AZ91D magnesium alloy fabricated by equal-channel angular pressing

Effect of microstructure change on corrosion behaviour of equal-channel angular pressed (ECAPed) AZ91D Mg alloy was investigated The ECAPed alloy with ultra-fine grained (UFG) alpha-phase matrix and refined beta-phase particles displays a significantly lower corrosion resistance resulting in more pits after in-situ corrosion, higher mass-loss rate immersed in NaCl solution larger I-corr values in polarization curves and lower fitted R-t values in EIS plots Two factors weaken the corrosion resistance the first is the strains-induced crystalline defects providing the alpha-phase matrix more corrosion activation the second is the refined beta-phase particles losing barrier to the corrosion propagation in alpha-phase matrix (C) 2010 Elsevier Ltd All rights reserved