Molecular static simulation of the effect of alkalline metal impurities on the bonding of Al atoms at the grain boundaries of aluminum

Unlike the iron based alloys, the embrittlement behavior of aluminum based alloys due to impurity segregation at the grain boundaries have not previously studied. Recently, experiments were performed on the Al-Mg alloys and it was found that more than 0.6ppm Na impurity atoms will cause embrittlement of these alloys. In the present study, we have created aluminum clusters containing about 20 atoms based on the structure of tilt grain boundaries and then performed the first-principle calculations on these clusters with or without alkalline metal impurity atom (Li, Na, K,). The overlap populations between aluminum atoms were calculated so as to find the effect of impurity atoms on the bonding between aluminum atoms. Na impurity atom was found to weaken the bonding between the aluminum atoms around it.