Dislocation-precipitate interaction and β'' deformation in Al–Mg–Si alloys: Ex-situ TEM stretching and molecular dynamics simulations
Studying the interaction between dislocation and precipitate phase is crucial for unraveling the aging strengthening mechanism of Al–Mg–Si alloys and for developing aging strengthening models specifically tailored for aluminum alloys. In this study, ex-situ stretching experiments were carried to exp...
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| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-09-01
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| Series: | Journal of Materials Research and Technology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785425019805 |
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| Summary: | Studying the interaction between dislocation and precipitate phase is crucial for unraveling the aging strengthening mechanism of Al–Mg–Si alloys and for developing aging strengthening models specifically tailored for aluminum alloys. In this study, ex-situ stretching experiments were carried to explore the interaction between dislocation and needle-shape βʺ precipitation phase through transmission electron microscopy (TEM). The experimental results indicated that the dislocation shears the needle-shape βʺ precipitation phase, resulting in bending and a change in morphology. The interaction of edge dislocations with β'' precipitate phase in Al–Mg–Si alloys is investigated by atomistic simulations. It is shown that in the finer-scale precipitate phase, the dislocations mainly shear through the precipitation in a nearly-synchronous manner and do not form complete and closed Orowan rings. However, for extended precipitate phase, the shearing process is characterized by dislocation splitting and incomplete cutting, forming complex ring defects. The results revealed a clear transition from a simple shear mechanism to a more complex precipitation-induced dislocation behaviour, providing insights into the strengthening mechanism of these alloys. The correlation among the critical decomposition shear stress (CRSS), the critical bending angle and the precipitate phase spacing is investigated. It is found that as the critical bending angle increases, the CRSS gradually decreases when the synchronized-complete-shear overcoming mechanism dominates, whereas the CRSS increases linearly with the critical bending angle when the dislocation-segmentation-shear overcoming mechanism dominates, suggesting that the extended precipitate phase pose a greater obstacle to dislocation motion. |
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| ISSN: | 2238-7854 |