Fatigue crack tip deformation process as influenced by the environment: McEvily, A.J. and Gonzalez Velazquez, J.L. Metall. Trans. A Aug. 1992 23A, (8), 2211–2221

Abstract

The creep behavior of dispersion-strengthened Al–8.5Fe–1.3V–1.7Si (8009 Al) has been investigated in the temperature range of 573–723 K. The results exhibit a high apparent stress exponent (14–18) and a high apparent activation energy for creep (296 kJ mol−1). The creep data were analyzed by incorporating a threshold stress into the power-law creep equation, which leads to a stress exponent of 5 indicating dislocation–climb mechanism. Traditional dislocation creep theories neither lead to correct values nor explain the origin or temperature dependence of the threshold stress, which is much stronger than that attributable to the shear modulus. A good correlation between experimental and theoretical prediction using the dislocation detachment model was obtained by adjusting the structure factor in the creep equation because the dislocation density is not well known. Dislocation/particle interactions as well as dislocation networks and subgrains are frequently observed after creep tests at different conditions.