Computer Simulation of Tilt Grain Boundaries in Alloys with L1<sub>2</sub> and B2 Superlattices

Abstract

Computer simulation of grain boundaries (GB) was carried out in alloys Ni 3 Al with L1 2 superlattice and NiAl with B2 superlattice. This work studies simmetrical tilt grain boundaries Σ=5 [100](012) and Σ=5 [100](013) (special boundaries) with an axis of turn [001] and with angles of misorientation θ = 53.1° and 36.9° The atomic interaction has been described by Morse empirical central-force potentials. The atomic structure and energy of GB were investigated by means of construction of γ-surface using three relaxation techniques rigid two-dimensional relaxation in which the atoms at shift of one grain relatively another remain in sites of corresponding lattices, rigid three-dimensional relaxation and full atomic relaxation It is shown that Σ=5 tilt GBs in Ni 3 Al and NiAl have several steady states Value of the GB excess volume was calculated. Comparison of our results with geometrical model of coincidence site lattice (CSL) was carried out, GBs in model CSL are unstable, the stabilization is achieved by additional displacement on some vector along the plane of defect.