Magnetic Properties of the Mechanically Alloyed (Fe0.85Mn0.15)0.3Cu0.7 System

Samples of nominal composition (Fe0.85Mn0.15)0.3Cu0.7 were prepared by mechanical milling starting from pure element powders. In order to elucidate the effect of the alloying time upon the magnetic properties of the system, milling times ranging from 1 hour up to 72 hours were considered. The phase distribution present on the as-milled materials was identified from the analysis of X-ray diffraction data. The room temperature magnetic properties of the samples were studied by means of 57Fe Mössbauer spectroscopy and vibrating sample magnetometry, whereas their low temperature magnetic behavior was characterized through magnetic susceptibility measurements. The results evidenced a strong dependence of the magnetic properties on the milling time and, concretely, the occurrence of a superparamagnetic behavior in the long-time-milled samples for which an extended solid solution was obtained. This fact is attributable both to the obtained crystallite sizes, which resulted to be of the order of a few nanometers, and to a milling-driven increase of the lattice parameter.