The bulk and interfacial structures of the η (Al2Au) precipitate phase

被引：12
作者：
Bourgeois, Laure [1 ,2 ]
Zhang, Zezhong [2 ]
Li, Jiehua [3 ]
Medhekar, Nikhil V. [2 ]
机构：
[1] Monash Univ, Monash Ctr Electron Microscopy, Clayton, Vic 3800, Australia
[2] Monash Univ, Dept Mat Sci & Engn, Clayton, Vic 3800, Australia
[3] Univ Leoben, Chair Casting Res, A-8700 Leoben, Austria
来源：
ACTA MATERIALIA | 2016年 / 105卷
基金：
澳大利亚研究理事会;
关键词：
Aluminium alloys; Precipitation; Atomic structure; Scanning transmission electron microscopy (STEM); ATOMIC-STRUCTURE; 1ST-PRINCIPLES CALCULATIONS; ALUMINUM; GROWTH; GOLD; ENERGETICS; KINETICS;
D O I：
10.1016/j.actamat.2015.12.035
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The atomic structure of the Al2Au eta precipitate phase in an Al-0.2 at. %Au alloy is investigated using high resolution scanning transmission electron microscopy together with first principles and elasticity theory calculations. We find experimentally that precipitates above a certain thickness exhibit the cubic crystal structure of the equilibrium phase eta. However below that thickness precipitates adopt a tetragonal distortion of the cubic structure of which can be regarded as an intermediate eta' phase and allows full two-dimensional coherence for very thin precipitates (up to two unit cells' thick). Despite the structural similarities of the bulk structures of eta and theta'(Al2Cu) precipitate phases, the former displays interfacial structures that differ markedly from those recently observed in theta'. This can be attributed to the much lower defect energy in aluminium of solute Au compared with solute Cu. Both first-principles and elasticity theory calculations are in good agreement with our experimental observations. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码：284 / 293
页数：10
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