AN INVESTIGATION OF MECHANICALLY ALLOYED FE-AL

An X-ray diffraction and Fe-57 Mossbauer effect spectra study of mecha nically alloyed Fe100-xAlx is presented. Alloys with 0 less than or eq ual to x less than or equal to 60 were prepared from elemental powders in a high energy ball mill. Alloys of the composition Fe50Al50 were a lso studied in detail as a function of milling time in order to better understand the phase formation in these alloys. X-ray measurements sh owed all fully milled samples to be of the bcc structure. Up to x=40, Mossbauer effect spectra showed the alloys to be ferromagnetic with a decreasing mean hyperfine field as a function of x. For x>40 no magnet ic splitting was observed indicating that the alloys are paramagnetic at room temperature. Hyperfine field distributions of the ferromagneti c alloys can be interpreted in terms of Fe neighbor environments as a function of Al content. As a function of milling time, the composition of the Fe50Al50 alloy may be described in terms of changing proportio ns of three different phases; a ferromagnetic bcc phase (FeAly), a par amagnetic fee phase (AlFey) and a paramagnetic bcc phase (FeAl). The r elative proportions, compositions and microstructures of these phases may be understood from the combined X-ray diffraction and Mossbauer ef fect measurements. (C) 1998 Elsevier Science S.A.