Mössbauer study of the ferromagnetic behavior of chromium-rich Fe-Cr alloys

Mössbauer spectra have been obtained as a function of temperature for ${\mathrm{Fe}}_x{\mathrm{Cr}}_{1-x}$ alloys with $x=0.20, 0.25, \mathrm{and} 0.30$. Analysis of the line widths yields Curie temperature values of 60, 160, and 260 K, respectively, in agreement with bulk magnetization measurements. The results show a broad distribution of hyperfine fields indicating a wide variation of iron magnetic moment values from site to site. This result is consistent with neutron-diffraction and Mössbauer experiments on alloys of higher Fe concentration. The most probable hyperfine field and the bulk magnetization follow a temperature dependence proportional to ${(1-\frac{T}{T_c})}^{\frac{1}{2}}$.