HOW DO ATOMS JUMP IN ORDERED ALLOYS - THE MODEL SYSTEM FE-AL

Our aim is to reveal the elementary diffusion jump of Fe atoms in orde red Fe-Al single crystals (Fe contents 50.5, 55, 66 and 75 at.%) by co mparing results from quasi-elastic Mossbauer spectroscopy at Fe-57 wit h results from other methods. The mechanism obviously follows one and the same logics irrespective of the alloy composition: Fe atoms jump i nto second or third nearest-neighbour sites on their own sublattice vi a the lying-between antistructure site on the Al sublattice. Since the disorder increases with increasing Fe concentration, the residence ti me of Fe atoms on the antistructure sites increases at the same time.