Crystallization of Fe73.5Cu1RE3Si13.5B9 ribbons with RE = Pr, Nd, Gd

The crystallization process in Fe73.5Cu1RE3Si13.5B9 ribbons with RE = Pr, Nd, Gd is investigated using differential scanning calorimetry, x-ray diffraction and Moessbauer spectrometry. The crystallization steps are characterized after both short time (1 h) isothermal annealing in the 350-650 deg. C range of temperature and long time (24 h) isothermal annealing at 650 and 700 deg. C. It is found that the crystallization process is the same for the Pr- and Nd-containing ribbons and the crystallization products are α-Fe(Si), Fe2B and (Fe,Si)23B6. For the Gd-containing sample, the crystallization occurs at a higher temperature, the same crystallization products are formed and Gd-containing phases are detected after 24 h, 700 deg. C annealing. The nature of the rare earth influences the crystallization kinetics, as the crystallization process for both Pr and Nd ribbons starts at a lower temperature and has a lower activation energy than that of the Gd ribbon, which is comparable to that of the Finemet alloy