Molecular Dynamics Study of Feco Phase Transitions and Thermal Properties Based on an Improved 2nn Meam Potential

Abstract

A semi-empirical potential in line with the second nearest-neighbor modified embedded-atom method (2NN MEAM) formalism has been improved for the Fe-Co interactions intended to reproduce the different thermal phases stability. Fundamental structural and elastic properties are correctly reproduced. Point defects have been included in the fitting and mainly the thermodynamic characteristics have been improved. Molecular dynamics simulations using this potential predict melting temperatures close to experiments and is the first potential showing a temperature induced B2 to L1 0 /hcp transformation. A disorder transformation is observed by diffusing vacancies at different temperatures and quantified by the long-range order parameter. The potential is applied to thin films of the metastable L1 0 structure by using fcc buffer layers, predicting good stability and energetical results comparable to ab initio calculations. The potential proves useful to study the different FeCo phases and to investigate multilayer films mainly under thermal effects.

Keywords: Atomistic simulation, Modified embedded-atom method, Fe-Co alloy, Phase transformation, L10 thin films