Creep and rupture behavior of a commercial aluminum-magnesium alloy A5083 at constant applied stress

Commercial aluminum-magnesium alloy was tested to examine the creep-rupture behaviour at constant applied stress. At the initial stage, the alloy showed the inverse transition creep with the incubation time. The incubation time would be induced through the release of the free dislocations from the magnesium atmosphere or/and second particles. Minimum strain rate was observed instead of steady state creep rate. The minimum strain rate had the dependence of the applied stress and temperature. The stress exponent was about 5.4 and the activation energy was about 2 10 kJ/mol. They were independent of the applied stress and temperature. The high activation energy was for the diffusion of magnesium atoms and of vacancies as the additional energy to continue the further creep deformation at constant applied stress. The Monkman-Grant relationship was observed between the minimum strain rate and the creep life. (C) 2004 Elsevier B.V. All rights reserved.