3D modelling of β" in Al-Mg-Si: Towards an atomistic level ab initio based examination of a full precipitate enclosed in a host lattice

被引：18

作者：

Ehlers, F. J. H. ^{[1
]}

Dumoulin, S. ^{[2
]}

Holmestad, R. ^{[1
]}

机构：

[1] Norwegian Univ Sci & Technol NTNU, Dept Phys, N-7491 Trondheim, Norway

[2] SINTEF, Mat & Chem, N-7465 Trondheim, Norway

来源：

COMPUTATIONAL MATERIALS SCIENCE | 2014年 / 91卷

关键词：

First-principles calculations; Aluminium alloys; Precipitate-host lattice interface energies; Multi-scale model scheme; ALLOYS; PLANE;

D O I：

10.1016/j.commatsci.2014.04.060

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We extend a first principles based hierarchical multi-scale model scheme for describing a fully coherent precipitate in a host lattice to 3D simulations. As our test system, the needle-shaped main hardening Al-Mg-Si alloy precipitate beta '' is chosen. We show that computational costs do not impose practical limits on the modelling: the scheme can probe the full interface energy for physically sized and well isolated precipitates. Examining a series of energetically competitive bulk beta '' configurations, we highlight a series of results: (i) the scatter in the structural parameters for different beta '' configurations clearly exceeds experimental uncertainties also when interaction with the host lattice is taken into account. (ii) Structural and compositional beta ''/Al interfaces generally coincide. This implies that precipitate stoichiometry is retained only for the two beta '' configurations with the lowest formation energy (compositions Mg5Al2Si4, Mg4Al3Si4). (iii) beta ''-Mg4Al3Si4 emerges as a minimum energy configuration for large precipitates. Finally, (iv) more complete modelling, with precipitates surrounded by Al in all three dimensions, is expected to highlight a non-negligible influence of the precipitate misfit along the main growth (needle) direction. (C) 2014 Elsevier B.V. All rights reserved.

引用

页码：200 / 210

页数：11

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