THE EFFECT OF BORON ON CHARGE-DENSITY DISTRIBUTION IN NI3AL

The electron charge density distributions rho(r) in both Ni-riched Ni3 Al single crystals with and without B-addition have been determined by the TEM-CBED technique and data refinement method in this work. The b oron addition introduces the fact that the bonding between the n.n. Ni -Ni pair is anisotropic: the metal bonding between Ni-site1-Ni of the next n.n. Ni-Ni pair, is strengthened and between Ni-site2-Ni is weake ned; the bonding between the n.n. Ni-Al pair is strengthened and that between Al-site1-Al (or Al-site2-Al) is weakened. The effects of the c hange in bonding on the properties and formation of interfaces with pr eferred structures in the two alloys are discussed. (C) 1997 Acta Meta llurgica Inc.