The discrete variational method within the framework of density functional theory is used to study the effect of zirconium on the electronic structure of the grain boundary in . The results for the interatomic energies show that the strength of the grain boundary is increased by the substitution of Zr for Al. The calculation of the charge distribution indicates that the directionality of the bonds in the grain boundary region is weakened by the addition of Zr. These results show that the alloying effect of Zr introduced into can significantly improve the ductility of , while strengthening the grain boundary.