Relationship between atomic ordering and fracture in Fe-Al alloys

Abstract

The fracture surfaces of slowly cooled Fe-Al alloys containing up to 28 at. % Al were examined using scanning electron microscopy techniques. It was found that the fracture modes changed from void coalescence to transgranular and finally, to intergranular as the Al concentration increased. The latter two modes of fracture were of the brittle type and were associated with the onset of long range order in these alloys. In particular, it has been postulated that atomic ordering leads to markedly reduced cross-slip, in turn reducing the degree to which void coalescence, with accompanying ductility, can occur.