title: The crystallization process of liquid vanadium studied by ab initio molecular dynamics.
abstract: We present a study of the crystallization process in liquid vanadium over a temperature range from 3000 K down to 1500 K using ab initio molecular dynamics simulations. Short-range order evolution during solidification is studied using various structural analysis methods. We show that the icosahedral-like short-range order is detected in the stable liquid phase and grows upon supercooling. The system undergoes a first-order phase transition (from a liquid to a solid state) at a temperature of about 1600 K. The crystal nucleation process is further studied using the time-temperature transformation mechanism by annealing the system at 1650 K. The nucleation is examined using bond-orientational order and density fluctuation analysis. Our finding is that various precursors appear in the region of high bond-orientational order with the majority having body-centered cubic (bcc)-like symmetry. This bcc-like region grows on annealing via thermal fluctuations. Our results reveal that the bond-orientational order precedes the density fluctuation, and is the main driving factor for nucleation.
authors.affiliation: International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, People's Republic of China.
authors.forename: T T
authors.initials: TT
authors.lastname: Debela
authors.forename: X D
authors.initials: XD
authors.lastname: Wang
authors.forename: Q P
authors.initials: QP
authors.lastname: Cao
authors.forename: D X
authors.initials: DX
authors.lastname: Zhang
authors.forename: J Z
authors.initials: JZ
authors.lastname: Jiang
mesh_terms: D003460:Crystallization; D007700:Kinetics; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D044367:Phase Transition; D013696:Temperature; D013816:Thermodynamics; D014639:Vanadium / Q000737:chemistry*
chemical_list: D014639:Vanadium