Interfacial interaction and prenucleation at liquid-Al/γ-Al2O3{1 1 1} interfaces. (14th January 2021)

• Record Type: Journal Article
• Authors: Fang, Changming; Yasmin, Sultana; Fan, Zhongyun
• Is Part Of: Journal of physics communications. Volume 5:Number 1(2021)
• Publication Date: 2021-01-14
• Subjects: Liquid-Metal/Oxide Interfaces -- Alumina Substrate -- ab initio molecular dynamics simulation -- heterogeneous nucleation -- surface roughness; Physics -- Periodicals; 530.05
• DOI: 10.1088/2399-6528/abd8eb
• Languages: English
• ISSNs: 2399-6528

Abstract

Abstract: Alumina ( α - and γ -Al2 O3 ) particles are formed in liquid Al-Mg alloys during the liquid dealing and cast processes. These native oxide particles have non-trivial influences on the microstructures and properties of the solidified parts, and may act as potential heterogenous nucleation sites during solidification. At present there is still a lack of understanding about the interaction and atomic arrangements at the interfaces between liquid-Al and γ -Al2 O3 substrates. Here we investigate the liquid-Al/ γ -Al2 O3 {1 1 1} interfaces by means of ab initio molecular dynamics simulations and electronic structure calculations. We found that the interfacial interaction at the interfaces leads to formation of an ordered terminating Al layer. This newly formed terminating Al layer is positively charged and chemically bonded to the substrate and thus, becomes part of the substrate. Analysis showed that the terminating Al layer contains vacancies and displacements, being atomically rough. The newly-formed Al layer is also structurally coupled with the substrates. These γ -Al2 O3 particles are weak templates for nearby liquid to nucleate. The present study sheds some light on the role of alumina particles in grain refinement of Al-based alloys during solidification processing.