Comparison of effects of sodium and silicon impurities on aluminium grain boundaries by first-principles calculation

We calculate the electronic structure of an Al Σ9(2 1)/[110] tilt grain boundary with substitutional sodium or silicon impurity atoms using the first-principles pseudopotential method. For the grain boundary with sodium impurities and that with silicon impurities, there exists obvious differences in the relaxed configuration, valence charge density and local density of states (LDOS), which indicates a different embrittlement-promotion mechanism for these two cases.