Molecular dynamics calculation of solid–liquid interfacial free energy and its anisotropy during iron solidification

Abstract

Different interatomic potentials of BCC Fe were assessed by comparing calculated melting point, enthalpy, density of BCC iron and radial distribution function in liquid iron. It was found that the Embedded Atom Method (EAM) potential by (Ackland et al., J. Phys.: Condens Matter. 16 (2004) S2629) predicts most accurate data for BCC crystal and liquid at melting conditions. Using this EAM potential, the BCC solid–liquid interfacial free energy and its anisotropy were calculated using: (1) classical nucleation theory (CNT), (2) cleaving, and (3) capillary fluctuation methods (CFM). The differences in the orientationally averaged interfacial free energy between the above three methods and the experiment were 3.4%, −5.1%, and −9.8%, respectively. The advantage of the CFM and the cleaving method is that they can be used to determine the interfacial free energy and its weak anisotropy. In metallic BCC Fe system, the anisotropy parameters ε1, and ε2 were determined: (3.50± 0.85)% and (0.10±0.14)% from CFM and (3.33±0.69)% and (0.29±0.24)% from the cleaving method.