The nature of the chemical bonding at boundaries in the '-phase was analyzed by using the extended Hückel molecular orbital method. It was concluded that the brittleness of the grain boundary could be attributed to the Coulombic repulsive force between similar atoms that were adjacent at the grain boundary. In particular, Al atoms strongly repelled each other. It was also concluded that B could bind to Ni and Al without decreasing the bonding energy between constituent atoms.

Molecular Orbital Approach to the Chemical Bonding at Grain Boundary in γ′-Ni3Al. Ito, O., Tamaki, H.: Acta Metallurgica et Materialia, 1995, 43[7], 2731-5