On the magnetism of the σ-phase Fe-Cr alloys

Magnetic properties of microcrystal line sigma-Fe100-xCrx (45 <= x <= 50) alloys were investigated with Mossbauer-effect and magnetization measurements performed as a function of temperature and external magnetic field up to 15 T. The Curie temperature, T-C, and the average magnetic moment per Fe atom, <mu >, which were determined, decrease linearly with x; the former at the rate of similar to 7 K/at% and the latter at the rate of 0.033 mu B/at%. The <mu >-values determined are significantly larger than those in the literature. The characteristic features of the magnetization curves are that they (a) do not saturate even at 15 T, and (b) show bending approximately up to 3 times the derived T-C values. The relationship between the average hyperfine field and <mu > was revealed to be non-linear. The latter, non-saturating character of isothermal magnetization curves and Rhodes-Wohlfarth plot are in favour of the itinerant model of magnetism in the investigated samples. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.