Crystallization behavior of amorphous (Fe100−xCox)85B15

Fe–Co–B amorphous alloys exhibit anomaly in their magnetic properties which has been attributed to a short-range order of Fe3Co or FeCo around specific Co concentrations. In the present work, crystallization behavior of amorphous (Fe100−xCox)85B15 has been studied in order to further elucidate the structural changes in the amorphous phase as a function of the Co concentration. The primary phase precipitating out is a bcc Fe–Co alloy while in the second crystallization step (Fe100−yCoy)2B compound is formed. An anomaly in the first crystallization temperature obtained from DSC measurements for composition x=24.7 is observed. During the initial stages of crystallization the Co concentration in the primary phase is close to the nominal Co concentration. However at later stages, in specimens with x>27, the concentration of Co increases and exceeds the nominal composition. Mössbauer measurements during annealing suggest a decrease in the inhomogenity of the remaining amorphous phase.