title: A computational study of diffusion in a glass-forming metallic liquid.
abstract: Liquid phase diffusion plays a critical role in phase transformations (e.g. glass transformation and devitrification) observed in marginal glass forming systems such as Al-Sm. Controlling transformation pathways in such cases requires a comprehensive description of diffusivity, including the associated composition and temperature dependencies. In the computational study reported here, we examine atomic diffusion in Al-Sm liquids using ab initio molecular dynamics (AIMD) and determine the diffusivities of Al and Sm for selected alloy compositions. Non-Arrhenius diffusion behavior is observed in the undercooled liquids with an enhanced local structural ordering. Through assessment of our AIMD result, we construct a general formulation for Al-Sm liquid, involving a diffusion mobility database that includes composition and temperature dependence. A Volmer-Fulcher-Tammann (VFT) equation is adopted for describing the non-Arrhenius behavior observed in the undercooled liquid. The composition dependence of diffusivity is found quite strong, even for the Al-rich region contrary to the sole previous report on this binary system. The model is used in combination with the available thermodynamic database to predict specific diffusivities and compares well with reported experimental data for 0.6 at.% and 5.6 at.% Sm in Al-Sm alloys.
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA.
authors.forename: T
authors.initials: T
authors.lastname: Wang
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA.
authors.forename: F
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA.
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.affiliation: Kuang-Chi Institute of Advanced Technology, Shenzhen, Guangdong 518000, China.
authors.forename: X W
authors.initials: XW
authors.lastname: Fang
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Zhou
authors.affiliation: 1] Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA [2] Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kramer
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA.
authors.forename: C Z
authors.initials: CZ
authors.lastname: Wang
authors.affiliation: 1] Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA [2] Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Ho
authors.affiliation: 1] Division of Materials Sciences and Engineering, Ames Laboratory, US DOE, Ames, IA 50011, USA [2] Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Napolitano