Studies on the magnetic behavior of the Fe4N.

E.L.PELTZER Y BLANCÁ, J.DESIMONI, S. COTTENIER, N.E. CHRISTENSEN AND L. ERRICO

Foz do Iguaçu, Brasil.

Conferencia; XIV International Conference on Hyperfine Interactions & XVIII International Symposium on Nuclear Quadrupole Interactions.; 2007

Due to its enormous importance for construction technology, the Fe-C and Fe-N binary systems are among the most thoroughly studied. Pure Fe is a rather soft material, with little or no attractive properties for engineering applications. By adding small amounts of C or N atoms that can be located to interstitial sites, the properties like structure and kinetics of phase transitions change completely and a variety of Fe (C/N) alloys with useful properties can be created. The fcc-Fe(C/N) alloys are widely used for the production of cast irons and steels when critical temperatures range and cyclic thermal conditions, corrosives atmospheres, etc, are the working conditions of the material.             The chemical activity data and Mössbauer spectroscopy have been traditionally used to check the different models and simulations. However, the solute distribution is still an open question. Accordingly, various models of austenite have been proposed which are based on assuming two sublattices, one for the Fe atoms and the second one for the mixture of solute atoms (X) and vacant octahedral interstices. The possibility of an structure of the Fe4X-type was also proposed to account for the solute distribution in the austenite structure. The electronic properties has been also subject of great interest since they are intimate correlated to the solute distribution and crystal structure of the alloys. The magnetic properties of interstitial solutions have also relevant technological implications and a great effort has been performed to provide an understanding of a variety of subtleties involved in physical and metallurgical properties. The ab-initio calculations, including spin-orbit (SO) coupling, of the fcc-Fe-N alloys with N atoms as solute  were performed in the present work. The hyperfine parameters obtained of the calculations were compared with experimental Mössbauer data base, also, the magnetic properties calculated were compared with the values showed in the literature. In general the calculated values are in close agreement with experimental data.