Atomic-scale quasi in-situ TEM observation on the redistribution of alloying element Cu in a B4C/Al composite at the initial stage of corrosion

Abstract The present study reports an atomic level quasi in-situ TEM observation of the redistribution of alloying element Cu in the corrosion process of a B4C-reinforced Al-Mg-Si-Cu composite. Cu atoms were found to combine with Mg and form a thin layer at the interfaces between the aluminum matrix and nano-reinforcements (i.e. Mg(Al)B2 and Al3BC). Dealloying of the Cu/Mg-rich layer was revealed. The following decomposition of Mg(Al)B2 resulted in narrow corrosion trenches forming around Mg(Al)B2 and then the localized pitting of the matrix. In addition, the liberated Cu ions were then redeposited and formed noble Cu nano-particles upon cathodic Mg(Al)B2 and B4C particles.