Analysis of the metastable precipitates in peak-hardness aged Al-Mg-Si(-Cu) alloys with differing Si contents

被引：156
作者：
Buchanan, K. [1 ,2 ]
Colas, K. [2 ]
Ribis, J. [1 ]
Lopez, A. [2 ]
Garnier, J. [1 ]
机构：
[1] Univ Paris Saclay, CEA, DEN Serv Rech Met Appl, F-91191 Gif Sur Yvette, France
[2] Univ Paris Saclay, CEA, DEN Serv Etud Mat Irradies, F-91191 Gif Sur Yvette, France
来源：
ACTA MATERIALIA | 2017年 / 132卷
关键词：
Aluminum alloys; 6061; Metastable phases; Transmission electron microscopy; Atom probe tomography; AL-MG-SI; ATOM-PROBE; CRYSTAL-STRUCTURE; BETA''-PHASE; CU; MICROSTRUCTURES; INTERFACE; STABILITY; BEHAVIOR; MISFIT;
D O I：
10.1016/j.actamat.2017.04.037
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The peak-hardness aged (T6) precipitates in 6061 (Mg:Si approximate to 2:1) and Si-enriched 6061 (Mg:Si approximate to 1:1.1) alloys have been characterized using transmission electron microscopy and atom probe tomography. Mg Si-Cu rich solute clusters/GP-zones, needle-shaped precipitates and lath-shaped precipitates coexist in both alloys at the T6 condition. The needle-shaped precipitates were dominant in both alloys. The alloy's overall composition strongly influences the needle-shaped precipitate's Mg:Si ratio and crystal structure. In the Si-enriched 6061 alloy these precipitates typically have an average Mg:Si ratio of 125:1 and monoclinic crystal structures in good agreement with the pre-beta" and beta" phases. The standard 6061 alloy's higher overall Mg:Si ratio increases the needle-shaped precipitate's average Mg:Si ratio to 1.65:1. This high ratio was a result of a reduction in the precipitate's Si content rather than an increase in the Mg content, which is believed to be enabled by the formation of needles with mixed beta"/disordered structures. The alloy's overall composition also influences the lath-shaped precipitate's crystal structure with Q' laths identified in the Si-enriched 6061 alloy while disordered L-phase laths were identified in the standard 6061 alloy. The current work shows that high Mg:Si ratio Al-Mg-Si(-Cu) alloys promote more disordered precipitate distributions. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
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页码：209 / 221
页数：13
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