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A systematic comparison of static and dynamic ageing of two Al–Mg–Si alloys
Aluminium alloys containing Mg and Si as the major solutes are strengthened by precipitation of the metastable precursors ( β″) of the equilibrium β (Mg 2Si) phase. In this study, both static and dynamic ageing of two Al–Mg–Si alloys—the 6061 (Al–1.34% Mg 2Si) and 6069 (Al–2.25% Mg 2Si) alloys—were...
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Published in: | Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2004-05, Vol.373 (1), p.65-71 |
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Main Authors: | , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Aluminium alloys containing Mg and Si as the major solutes are strengthened by precipitation of the metastable precursors (
β″) of the equilibrium
β (Mg
2Si) phase. In this study, both static and dynamic ageing of two Al–Mg–Si alloys—the 6061 (Al–1.34% Mg
2Si) and 6069 (Al–2.25% Mg
2Si) alloys—were aged at 170
°C and compared to evaluate the potential for improving the mechanical properties. Dynamic ageing was conducted through the procedure of equal channel angular extrusion (ECAE). It is shown that the ageing time scale is reduced from ∼1000
min for conventional static peak-ageing to ∼10
min by using ECAE-aided dynamic ageing. Compared to the significant strengthening effect in static peak-ageing treatment, a notable further increase in ultimate tensile strength (UTS) is achieved by dynamic ageing: over 40
MPa for the 6061 alloy and 100
MPa for the 6069 alloy. Ductility of dynamically aged alloys is found to be comparable to that of the statically peak-aged samples. Microstructures of both statically and dynamically aged alloys were characterised using transmission electron microscopy; dislocation-assisted precipitation was observed to be the primary precipitate nucleation and growth mechanism during dynamic ageing process. It is concluded that dynamic ageing using ECAE is efficient in executing ageing treatment that results in superior mechanical properties of the Al–Mg–Si alloys. |
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ISSN: | 0921-5093 1873-4936 |
DOI: | 10.1016/j.msea.2003.12.035 |