Crystallization behaviour of (Fe,Co)SiB-CuNb alloys

Crystallization behaviour of two (Fe,Co)(73.5) Si13.5B9Cu1Nb3 alloys with 13.5 and 60 at.% Co has been studied by differential scanning calorimetry (DSC), thermomagnetic gravimetry (TMG), X-ray diffraction and electron microscopy. The devitrification process for both alloys takes place through two main stages, being the temperatures of the two crystallization events about 60 K lower for the Go-rich alloy. Precipitation of a metal-rich alpha-(Fe,Co)Si nanophase, with a mean grain size of 10-15 nm for Fe-rich alloy and 20-25 nm for the Go-rich alloy, is associated to the first crystallization stage. Nanocrystallization kinetics derived from non isothermal DSC and from isothermal TMG gives values close to 1 for the Avrami exponent for the two studied alloys.