Oscillatory relaxations in (111) planar defects in Ni<inf>3</inf> Al

Abstract

Computer simulation results are presented for various types of planar defect occurring on the (111) plane of the intermetallic compound Ni3 A1. The relaxed defect structures produce oscillations in the static displacements, both perpendicular and parallel to the boundary plane. This type of relaxation behaviour is related to the fact that the ordered lattice contains more than one atom per lattice site. Therefore, two different types of static distortion mode are found which, by analogy with lattice vibration modes, are called acoustic and optical. For the planar defects studied here, these two types of distortion mode were separated and it was found that the optical distortion mode is of similar nature in all of them. The acoustic mode is similar to that found in pure Ni and A1. © 1989 Taylor & Francis Group, LLC.