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A computational study of diffusion in a glass-forming metallic liquid

TitleA computational study of diffusion in a glass-forming metallic liquid
Publication TypeJournal Article
Year of Publication2015
AuthorsWang, T, Zhang, F, Yang, L, Fang, XW, Zhou, SH, Kramer, MJ, Wang, CZ, Ho, KM, Napolitano, RE
JournalScientific Reports
Volume5
Pagination10956
Date Published06
Type of ArticleArticle
ISBN Number2045-2322
Accession NumberWOS:000356082800001
Keywordsal-sm, aluminum, amorphous-alloys, crystallization behavior, impurity-diffusion, initio molecular-dynamics, rapid solidification, self-diffusion, sm binary-system, supercooled 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.

DOI10.1038/srep10956
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Structures and Dynamics