Mössbauer investigation of Fe-Mn-Cu nanostructured alloys obtained by ball-milling

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

HYPERFINE INTERACTIONS

SPRINGER

Año: 2005 vol. 161 p. 171 - 176

0304-3843

 Fe79Mn21, (Fe79Mn21)90Cu10, and (Fe79Mn21)80Cu20, alloys, prepared by high energy  ball milling were characterized by Mo¨ssbauer spectroscopy, X-ray diffraction and ac-susceptibility.  Results indicate that the Cu addition favors the formation of a FCC phase with two different  magnetic states at room temperature, i.e., an antiferromagnetic and a paramagnetic one. Thermal  evolution of the Mo¨ssbauer spectra revealed the occurrence of a magnetic ordering along a wide  temperature range. This behavior is probably related to Fe atoms in FCC-Fe(Mn,Cu) phase having  different environments and grain size distribution. Thermal dependence of in-phase ac-  susceptibility shows that a long range ordering starts at 240 K for the Fe79Mn21 alloy and shifts  towards lower temperatures with the Cu content. These results would reflect a long-range magnetic  ordering transition with a distribution of ordering temperatures rather than a blocking process of  particle single-domains.