Structure and magnetic properties of Fe-Mn-Cu alloys

M. MIZRAHI, A. F.CABRERA, S. J. STEWART AND J. DESIMONI

La Plata

Workshop; 35Th anniversary of Hyperfine interactions at La Plata; 2005

Mechanical milling has been widely used to synthesize new materials such as supersaturated solid solutions, amorphous and metaestable phases, as well as to induce phase transitions and alloy pure metallic elements. Materials obtained in this way present a high degree of structural disorder and nanometric crystallite sizes that significantly influence their physical properties. In this work we report on the characterization by Mössbauer spectroscopy, X-ray diffraction and AC susceptibility of mechanically milled samples of composition (Fe79Mn21)1-xCux (x=0, 0.1, 0.2 y 0.3). The samples were prepared in a horizontal ball mill at 30 Hz from the elemental constituents (Fe, Mn and Cu). The X-ray results indicate that the main formed phase has FCC symmetry. The Mössbauer spectra with rather broad linewidths suggest the existence of different iron environments. A kink near 245 K is observed in the AC susceptibility, which shifts to lower  temperatures with the Cu content. These results associated with magnetization measurements as function of temperature and applied field provides evidence for a highly disordered magnetic system.