Creep deformation of oxide-dispersion-strengthened Fe-40Al intermetallic:: thermal and athermal contributions

The creep behaviour of an Fe-40Al alloy containing Y2O3 particles has been analysed combining microstructural information and experimental data obtained from mechanical tests. The creep strength of the alloy is controlled by the dislocation-particle attractive interactions. At 500 degrees C the dislocation overcomes the dispersoid particles by a detachment-controlled process while at 700 degrees C general climb is the controlling mechanism. Both processes are thermally activated such that vacancy diffusion through the lattice determines the velocity at which the obstacles can be overcome. The rapid fall in creep strength observed between 500 and 700 degrees C has been explained by the rapid increase in diffusivity as vacancy concentration and mobility both increase dramatically. (C) 1999 Elsevier Science Ltd. All rights reserved.