Dislocation properties of polycrystalline Fe-Cr-Al alloys and their correlation with mechanical properties

The microstructure of four Fe-Cr-Al alloys containing 9.3-18.0 at.% chromium and 25.5-7.6 at.% aluminum has been investigated by transmission electron microscopy after different heat treatments and different degrees of compressive deformation. The properties of single dislocations and their arrangement in different states of deformation are discussed with respect to the corresponding state of order and work-hardening curves. The maximum of the work-hardening curves is shifted to higher strains with increasing aluminum concentration. The transition from increasing to decreasing work-hardening is correlated with a change of the dislocation arrangement from planar to non-planar. A significant effect of vacancy formation on the dislocation structure and deformation process could not be observed. At a deformation temperature of 400 degrees C dynamic strain aging occurs. (C) 2000 Elsevier Science S.A. All rights reserved.