Mechanism of low temperature deformation in aluminium alloys
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in: Materials science and engineering: A, Structural materials: properties, microstructure and processing, Jahrgang 795, Nr. 795, 139935, 23.09.2020.
Publikationen: Beitrag in Fachzeitschrift › Artikel › Forschung › (peer-reviewed)
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TY - JOUR
T1 - Mechanism of low temperature deformation in aluminium alloys
AU - Gruber, Belinda
AU - Weißensteiner, Irmgard
AU - Kremmer, Thomas
AU - Grabner, Florian
AU - Falkinger, Georg
AU - Schökel, Alexander
AU - Spieckermann, Florian
AU - Schäublin, Robin
AU - Uggowitzer, Peter
AU - Pogatscher, Stefan
N1 - Publisher Copyright: © 2020 The Author(s)
PY - 2020/9/23
Y1 - 2020/9/23
N2 - 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.
AB - 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.
KW - Aluminium alloys
KW - Cryogenic temperature
KW - Dislocation density
KW - In-situ TEM
KW - Synchrotron radiation
UR - http://www.scopus.com/inward/record.url?scp=85089092743&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2020.139935
DO - 10.1016/j.msea.2020.139935
M3 - Article
VL - 795
JO - Materials science and engineering: A, Structural materials: properties, microstructure and processing
JF - Materials science and engineering: A, Structural materials: properties, microstructure and processing
SN - 0921-5093
IS - 795
M1 - 139935
ER -