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 obtain ed from mechanical tests. The creep strength of the alloy is controlled by the dislocation-particle attractive interactions. At 500 degrees C the disl ocation overcomes the dispersoid particles by a detachment-controlled proce ss while at 700 degrees C general climb is the controlling mechanism. Both processes are thermally activated such that vacancy diffusion through the l attice determines the velocity at which the obstacles can be overcome. The rapid fall in creep strength observed between 500 and 700 degrees C has bee n explained by the rapid increase in diffusivity as vacancy concentration a nd mobility both increase dramatically. (C) 1999 Elsevier Science Ltd. All rights reserved.