THERMAL-STABILITY OF THE UNSTABLE FCC-FE50CU50 PHASE PREPARED BY MECHANICAL ALLOYING

An unstable fcc-Fe50Cu50 alloy has been prepared by milling of element al powder blends. The structure and the decomposition behavior of the alloy were studied by x-ray diffraction and Mossbauer spectroscopy. A broad distribution of different local environments of the iron atoms w as observed in the fcc-FeCu phase. This indicates that Fe and Cu are m ixed on an atomic level. In the initial state of decomposition, iron a toms precipitated coherently in the fcc-FeCu matrix as fcc-Fe particle s. At higher annealing temperatures the particle size increased during the thermal treatment, and the fcc-Fe precipitates transformed into t he bcc-Fe structure.