RADIATION-INDUCED SEGREGATION IN PROTON-IRRADIATED AUFE STUDIED BY MOSSBAUER-SPECTROSCOPY

Radiation-induced segregation is studied in dilute Au-1.0at.%Fe alloys after proton irradiation at 220-degrees-C. After proton irradiation a new Mossbauer line appears with hyperfine parameters independent of the irradiation dose. This line is assigned to small Fe complexes, which do not correspond to substitutional Fe clusters. These complexes are segregated within or in the neighbourhood of sinks and seem to be repeated as a 'motif', together with Fe atoms on substitutional sites of the Au lattice, within the segregations. Fast interstitial Fe diffusion could be the reason for the segregation. At 5 K a large hyperfine field of 35 T is found to act at these Fe complexes. This field remains up to the temperature region of 30 K. Both this hyperfine field and the transition temperature are larger than the corresponding values for substitutional Fe atoms (21.5 and 13 K, respectively).