Analysis of the EAM and MEAM Potentials for Modeling Localized States of the Ni₃Al and Pt₃Al Crystals

Abstract

Thermodynamic computer models of real alloys are based, first of all, on the choice of a particle interaction potential. The chosen potential often determines, to a great extent, the final result. The potential should numerically describe the properties of investigated materials qualitatively and as accurately as possible. The aim of this study is to analyze numerically the properties of the Ni₃Al and Pt₃Al crystals using the potentials obtained by the embedded-atom method (EAM). Classical EAM potentials and modified EAM (MEAM) potentials are considered with allowance for directional bonds. The lattice parameters, phonon spectra, elastic constants, and melting points of the proposed fcc intermetallics with the L1₂ superstructure have been calculated. The characterization of the crystals with the maximum accuracy allows one to construct realistic thermodynamic models with a required degree of reliability in studying localized states of the crystal lattices. The alloys under study find wide application, in particular, under intense external impacts. This leads to the manifestation of nonlinearity of the bonds and the formation of various localized states both in the bulk of the crystals and on their surface. In particular, solitary waves, nonlinear localized modes, and defect structures can be formed. The results obtained show that the investigated potentials describe satisfactorily the main properties and can be used to study the lattice dynamics in the bulk of a crystal. At the same time, the MEAM potentials seem preferable in studying surface effects and boundary temperature and pressure parameters.