Nanocrystallization behaviour of FeSiBCu(NbX) alloys

The crystallization of amorphous Fe73.5Si13.5B9Cu1Nb1X2 (X = Zr, Nb, Mo, V) was investigated by combined use of differential scanning calorimetry, X-ray diffraction and electron microscopy techniques. The addition of refractory elements raises thermal stability of the amorphous alloys in the order V < Mo < Nb < Zr. The nanocrystallization reaction exhibits a low rate kinetic, as denotes the value close to 1 of the Avrami index. The volume fraction of the nanophase for the same annealing conditions decreases in the order V > Mo > Nb > Zr but a maximum value of about 65% is found for all cases. Refractory element alloying controls the mean grain size of the Fe,Si nanocrystals, growing up to a value in the range 10–18 nm for the alloys in the sequence V > Mo > Nb > Zr.