Campus Units

Materials Science and Engineering, Physics and Astronomy, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

6-9-2015

Journal or Book Title

Scientific Reports

Volume

5

First Page

10956

DOI

10.1038/srep10956

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.

Comments

This article is published as Wang, T., F. Zhang, L. Yang, X. W. Fang, S. H. Zhou, M. J. Kramer, C. Z. Wang, K. M. Ho, and R. E. Napolitano. "A computational study of diffusion in a glass-forming metallic liquid." Scientific Reports 5 (2015): 10956. DOI: 10.1038/srep10956. Posted with permission.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Copyright Owner

The Authors

Language

en

File Format

application/pdf

Share

COinS