On the cyclic deformation response of ultrafine-grained Al-Mg alloys at elevated temperatures

The role of solid solution hardening on cyclic stability was investigated in ultrafine-grained (UFG) aluminum-magnesium (Al-Mg) alloys at elevated temperatures. Up to 150 degrees C, the pinning of dislocations by Mg solute atoms in the All matrix imposed by solid solution hardening promotes cyclic stability. Above 150 degrees C, however, thermally activated grain coarsening governs the deformation response under cyclic loading, resulting in cyclic softening. Furthermore, the higher solute concentration increases the fatigue lives and performance at all temperatures. The current results emphasize the effectiveness of solid solution hardening in enhancing the cyclic stability and improving the fatigue performance of UFG materials. (C) 2008 Elsevier B.V. All rights reserved.