Anomalous creep behaviour of aluminium high current joint materials


During creep deformation the technical aluminium alloys EN AW-1350 (Al99.5) and EN AW-6060 (AlMgSi0.5) under certain conditions of stress and temperature show deformation thrusts of several millimetres, indicating discontinuous dynamic recrystallization. To study this anomalous creep behaviour in more detail the alloys were characterized by global and local texture measurements using neutron and electron backscatter diffraction (EBSD), respectively. In the case of AlMgSi0.5 the main global texture component of the undeformed sample is the cube component. During deformation and dynamic recrystallization a Goss component develops. The grain size slightly decreases with dynamic recrystallization. The normal creep behaviour is characterized by a Norton exponent of 3.8 and an activation energy of 0.5 eV. These parameters indicate that the strain rate controlling process is dislocation creep.
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