It was noted that this alloy was resistant to long-term creep at 100 to 130C (43% of the absolute melting point). The role played by thermal activation in dislocation mechanisms was analyzed by using accelerated creep tests performed at 150C, under a 280MPa load, and by subsequent observation of the dislocation microstructures by transmission electron microscopy. It appeared that thermal activation favored cross-slip activity, and permitted dislocations to glide on non close-packed planes; that is, {001}. This was the first time that evidence of primary {001} glide had been reported. In association with a strain-assisted decrease in the precipitate density, thermal activation softened the material and seemed to contribute to acceleration of the strain rate (tertiary stage) by facilitating the by-passing of precipitates and the production of mobile dislocations. The various creep stages were explained in terms of individual dislocation mechanisms, and not by reference to the evolution of dislocation sub-structures.

A 2xxx Aluminum Alloy Crept at Medium Temperature - Role of Thermal Activation on Dislocation Mechanisms. J.Majimel, M.J.Casanove, G.Molénat: Materials Science and Engineering A, 2004, 380[1-2], 110-6