Mechanism of low temperature deformation in aluminium alloys
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Date
2020-09-23
Publication Type
Journal Article
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yes
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Abstract
This study investigates differences in the deformation mechanisms between room temperature (296 K) and cryogenic temperatures (77 K) and their advantages for low temperature formability in alloys EN AW 1085, EN AW 5182 and EN AW 6016. Compared to room temperature behaviour, tensile tests showed an overall increase in yield strength, ultimate tensile strength and uniform elongation with differences among the principal alloy types. In general, the improved mechanical properties result from higher strain hardening rates at lower temperatures. The application of an extended Kocks-Mecking approach showed a significant reduction of the dynamic recovery and suggested higher dislocation densities upon cryogenic deformation. This was confirmed via in-situ synchrotron experiments, which also reveal a higher proportion of screw dislocations. Moreover, kernel average misorientation maps from electron backscattered diffraction and in-situ cryogenic deformation in a transmission electron microscope displayed a more uniform dislocation arrangement with a reduction of slip lines and less highly misaligned areas after deformation at lower temperatures. Supported by a detailed characterization of the microstructure and its dislocation structure, the associated fundamental mechanisms we reveal, which are at the origin of the exceptional improvement in mechanical properties, are extensively discussed.
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published
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Journal / series
Volume
795
Pages / Article No.
139935
Publisher
Elsevier
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Edition / version
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Date collected
Date created
Subject
Aluminium alloys; Cryogenic temperature; Dislocation density; Synchrotron radiation; In-situ TEM
Organisational unit
03661 - Löffler, Jörg F. / Löffler, Jörg F.
02891 - ScopeM / ScopeM