Contamination from the Milling Atmosphere and its Effect on Magnetic Properties of Fe/Al Nanopowders

FeAl nanosystems had been prepared by means of high energy ball milling for 5, 15, and 20 h in air environment to observe mechanochemical reactions with atmospheric oxygen and its effect on bulk magnetic properties. The detailed analysis of the corresponding magnetic properties of oxidized Fe-Al powders was carried out by means of two complementary techniques: vibrating sample magnetometer (VSM) and Mossbauer spectroscopy. At 8 nm particle size, along with bcc Fe/Al peaks, the traces of the Fe-O, Fe2O3 phases also have been observed. The large differences in values of bulk magnetic properties can be ascribed to the presence of nonmagnetic Fe oxides at different levels which deteriorates bulk magnetization (i.e>70% of an unmilled) of the prepared nanosystems effectively.