Distributions of hyperfine parameters in amorphous Fe78Al4Nb5B12Cu1 alloys

Amorphous state of ribbon-type melt-spun Fe78Al4Nb5B12Cu1 alloy has been studied by Moessbauer spectroscopy. A revised Vincze method was proposed and the distribution of hyperfine field, isomer shift, and quadrupole line broadening of the sample at various temperatures between 13 and 400 K have been evaluated. Temperature variation of average hyperfine field could be explained by Handrich's molecular field model. It was also found that half-width of the hyperfine field distribution was 4.7 T at 13 K and that it was nearly constant up to 400 K. Average line broadening due to quadrupole splitting distribution decreases with increasing temperature from 0.31 mm/s at 13 K to 0.19 mm/s at 400 K, whereas that due to isomer shift distribution is effectively unchanged at 0.045 mm/s. Curie temperature of amorphous Fe78Al4Nb5B12Cu1 alloy was determined to be 450 K