Precipitation hardening: unravelling mechanisms of trade-off between strength and ductility/formability of Al-Mg-Si alloys
File(s)
Published version
Author(s)
Zhang, Ruiqiang
Wang, Wei
Jiang, Jun
Type
Journal Article
Abstract
Heat treatable aluminium alloys have widespread applications in various industries owing to their significant strengthening capability through certain heating and cooling processes. However, these processes result in a trade-off between strength and ductility/formability, and the underlying fundamental mechanisms remain poorly understood. In this study, a multi-scale investigation was conducted on a heat treatable Al-Mg-Si alloy to explore the mechanisms underlying the trade-off between strength and ductility/formability. Three different tempers T6, T4, and O were produced, each leading to the formation of different second-phase precipitates. Uniaxial tensile tests and Nakajima punch tests were carried out to quantify the alloy’s ductility and formability, respectively. These mechanical properties were subsequently linked to the microstructure of the alloy by conducting micro uniaxial tensile tests alongside in-situ microstructural characterisations. The results indicate that the trade-off mechanisms arise from the competition between deformation occurring within the grain interiors and deformation near the grain boundaries. In the T6 temper alloy, precipitates significantly impede slip within the grain interiors, leading to strain concentration near the grain boundaries and the occurrence of intergranular fractures. Consequently, the T6 temper alloy exhibits the lowest ductility and formability. In contrast, slip occurs throughout all grains in the O temper alloy, thereby accommodating more deformation and resulting in the highest ductility and formability. Additionally, the precipitates in the alloy affect the dispersion of the geometrically necessary dislocation (GND) density. This study sheds light on the fundamental understanding of how precipitates influence the trade-off between the enhancement of strength and the simultaneous reduction of both ductility and formability.
Date Issued
2025-01-25
Date Acceptance
2024-12-31
Citation
Journal of Alloys and Compounds, 2025, 1012
ISSN
0925-8388
Publisher
Elsevier BV
Journal / Book Title
Journal of Alloys and Compounds
Volume
1012
Copyright Statement
© 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Identifier
10.1016/j.jallcom.2025.178443
Publication Status
Published
Article Number
178443
Date Publish Online
2025-01-02