Mössbauer and X-Ray Characterization of Fe_0.2Mn _0.4Al_0.4 Mechanically Alloyed Powders

A series of powders of Fe_0.2Mn_0.4Al_0.4 system were produced by mechanical alloying for 2, 4, 6, 8, 12, 24 and 48 hours milling and then characterized by ⁵⁷Fe Mössbauer spectrometry and X-ray diffraction at room temperature. X-ray patterns reveal the presence of Bragg peaks due to fcc Al, fcc Mn, and bcc Fe parent powders, whenever the alloying time is ranged from 2 to 12 hours, but the intensity of those peaks decreases when the alloying time increases. Also can be noted the rise of new broadened peaks, from 6 h alloying; their intensity increases with the alloying time. Those peaks correspond to the occurrence of a bcc and a fcc structural-type, attributed to the formation of the ternary FeMnAl alloys which are consolidated for longer alloying times. These phases are typical for alloys with high Mn content as well. Three regimes can be distinguished from the evolution of both room-temperature Mössbauer spectra and X-ray pattern as a function of alloying time.