Moessbauer Spectroscopy Study of Amorphous Fe sub 87 B sub 11 Au sub 2 Ribbon and Its Crystallization Products

摘要

Substantial increases in Fe saturation magnetization have been obtained in amorphous Fe-B containing small concentrations of gold. This material is also stable above 300 K, and thus has considerable practical significance. This paper reports the results of an investigation of amorphous Fe sub 87 B sub 11 Au sub 2 ribbon and its crystallization products based on exp 57 Fe Moessbauer spectroscopy. The amorphous ribbon exhibits a broad magnetic hyperfine splitting pattern typical of a metallic glass with an effective hyperfine field, H/sub eff/ = 257 kOe, and an isomer shift of 0.058 mm/s relative to metallic Fe at 300 K. The spectra of samples annealed for 25 min between T/sub A/ = 618 K and 708 K arise from a metastable amorphous phase of Fe-Au-B and a crystalline alpha -Fe phase. H/sub eff/ of the metastable amorphous phase decreases with respect to increased annealing temperature. However, H/sub eff/ of the alpha -Fe phase increases from 331 kOe for samples annealed at 618 K to 334 kOe for those annealed at 708 K. This increase can be attributed to an increased content of Au in the alpha -Fe phase. Annealing the samples at temperatures above 753 K for 25 min yields crystalline alpha -Fe and the intermetallic compound Fe sub 2 B. (ERA citation 08:054216)