Anisotropy and roughness of the solid-liquid interface of BCC Fe

• Published in: Journal of molecular modeling 2015-02, Vol.21 (2), p.32-32, Article 32
• Main Authors: Sun, Yongli, Wu, Yongquan, Lu, Xiuming, Li, Rong, Xiao, Junjiang
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Computer Appl. in Life Sciences; Computer Applications in Chemistry; Molecular Medicine; Original Paper; Theoretical and Computational Chemistry
• ISSN: 1610-2940; 0948-5023
• DOI: 10.1007/s00894-015-2569-5

Melting point T m and kinetic coefficient μ (a proportional constant between the interfacial velocity ν and undercooling Δ T ), along with the structural roughness of the solid-liquid interface for body centered cubic (BCC) Fe were calculated by molecular dynamics (MD) simulation. All simulations applied the Sutton-Chen potential, and adopted average bond orientational order (ABOO) parameters together with Voronoi polyhedron method to characterize atomic structure and calculate atomic volume. Anisotropy of T m was found through about 20~40 K decreasing from [100] to [110] and continuously to [111]. Anisotropy of μ with three low index orientations was found as: μ s,[100] > >  μ s,[110]  >  μ s,[111] for solidifying process and μ m,[100] > >  μ m,[111]  >  μ m,[110] for melting process. Slight asymmetry between melting and solidifying was discovered from that the ratios of μ m / μ s are all slightly larger than 1. To explain these, interfacial roughness R int and area ratio S / S 0 (ratio of realistic interfacial area S and the ideal flat cross-sectional area S 0 ) were defined to verify the anisotropy of interfacial roughness under different supercoolings/superheatings. The results indicated interfacial roughness anisotropies were approximately [100] > [111] > [110]; the interface in melting process is rougher than that in solidifying process; asymmetry of interfacial roughness was larger when temperature deviation Δ T was larger. Anisotropy and asymmetry of interfacial roughness fitted the case of kinetic coefficient μ very well, which could give some explanations to the anisotropies of T m and μ .