A Mössbauer spectrometry study of the kinetics of short-range ordering in FeCo

Abstract

Making use of the systematics of ⁵⁷Fe hyperfine magnetic fields (HMFs) in b.c.c. Fe-Co alloys, we have performed a Mössbauer spectrometry study of the disorder→order transformation in FeCo. Features of the ⁵⁷Fe HMF distribution were used to identify: (1) the numbers of ⁵⁷Fe atoms near antiphase domain boundaries, and (2) the numbers of ⁵⁷Fe atoms situated on Co sites. To produce an initial state of disorder, the alloys were rapidly quenched, mostly by the piston-anvil technique. Low-temperature annealings were then used to prepare different degrees of short-range order in these materials. The number of ⁵⁷Fe atoms near antiphase domain boundaries decreases more quickly with ordering than the number of 57Fe atoms situated on Co sites. This is consistent with a picture in which a dense formation of small moderately ordered domains develops very quickly, and the domains grow quickly. This is followed by an increase of order within the domains.