Mössbauer study of the metaestable gamma and epsilon phases in the Fe-Mn-Si system

J. MARTÍNEZ; S.M. COTES; J. DESIMONI

, Salón Dorado del Palacio Municipal, La Plata, Argentina

Conferencia; 35th Anniversary Hyperfine Interactions at La Plata; 2005

Departamento de Fisica - UNLP

Fe-Mn-Si alloys present the so-called shape memory effect (SME), which is governed by the reversible g«e martensitic transformation [1,2]. These g and e phases are metastable in this system and have the fcc and hcp structures, respectively. These particular alloys hold researchers a large attention due to the fact that they show better physical properties than others, cheaper preparation costs and suitable transformation temperatures, which make them more attractive for industrial applications. It is well known that the addition of Si to the binary Fe-Mn system enhanced the shape memory effect. Among other reasons, this happens because the Si additions strong decrease the Néel temperature of the g phase [3]. The aim of this work is to quantitatively describe the effects of Si on the hyperfine parameters of the metaestable g and e phases in Fe-Mn-Si alloys as a function of composition, by applying the Mössbauer spectroscopy (MS) technique. In this way, alloys in the concentration range from 15 to 30 wt % Mn and 0 to 12 wt % Si were prepared in an arc furnace and received suitable heat and surface treatments. Specimens were studied using CEMS.  The study was combined with other techniques, such as X-ray diffraction and neutron diffraction, which gave complimentary information.   [1] A. Sato, E. Chishima, K. Soma and T. Mori, Acta metall. 30 (1982) 1177. [2] H. Otsuka, M. Murakami, S. Matsuda, Proc. MRS Int. Meet. On Advanced Materials, Materials Research Society, Pittsburgh, PA, 9 (1989), 451. [3] M. Murakami, H. Suzuki, Y. Nakamura, Trans. ISIJ, 27 (1987) B87.