MOSSBAUER AND AC-SUSCEPTIBILITY INVESTIGATIONS OF THE ALLOY SERIES FEAL1-XMNX

Mossbauer and AC-susceptibility measurements have been carried out on the alloy series FeAl1-xMn(x) within the range 0.05 less-than-or-equal-to x less-than-or-equal-to 0.40. Mossbauer spectra reveal the presence of electron charge density and magnetic hyperfine field (B(hf)) distributions at two iron sites. The charge density rises linearly with Mn concentration while B(hf) increases non-linearly with x indicating a polarized spin density of the itinerant electrons at the Fe nucleus due to the near neighbouring Fe and Mn magnetic moments. The onset of magnetism is explained by the formation of magnetic moment at the iron atom when A1 atoms are removed and by the nearest neighbouring iron clustering. Magnetic measurements indicate the presence of mictomagnetic clusters and show a transition from paramagnetic state to magnetic glass state for all the alloys. No onset of ferromagnetism with increasing x was observed even at the concentration x = 0.4, in contrast to that observed in FeAl1-xCu(x) at a lower concentration x = 0.325. Comparison of the transition temperatures obtained from Mossbauer and AC-susceptibility measurements indicate relaxations of the magnetic clusters.