CRYSTALLIZATION OF (FE, CO)(78)SI9B13 ALLOYS - INFLUENCE OF RELAXATION PROCESSES

Crystallization of Fe78-xCoxSi9B13 amorphous alloys has been studied b y differential scanning calorimetry (DSC), thermomagnetic gravimetry a nd X-ray diffraction techniques. Thermal stability of the amorphous al loy monotonically decreases with increasing cobalt content. The devitr ification process as detected by DSC occurs in two main stages partial ly overlapping in temperature, but magnetic characterization reveals a third stage for cobalt-rich alloys. Primary precipitation of alpha-(F e, Co) is followed by a polymorphic reaction to give (Fe, Co)(2)B phas e. Fe3B-type phase is also detected at the end of the first crystalliz ation stage for iron-rich alloys and beta-Co(Si) and Co2B phases are f ound in fully crystallized samples for x = 60. The influence of relaxa tion processes on the crystallization was investigated, but no signifi cant effects of pre-annealing on the crystallization parameters result ed. (C) 1998 Chapman & Hall.