Analysis of nanocrystallization process in Fe73.5Cu1Nb3Si15.5B7 alloys by cumulant expansion of EXAFS

Amorphous-nanocrystalline transformation in Fe73.5Cu1Nb3Si15.5B7 is investigated by extended X-ray absorption fine structure (EXAFS) and analysed by the cumulant method, which allows a refined study of parameters that are able to describe the local structure during the nanocrystallization. The nearest-neighbour interatomic distance and coordination number have been determined for Fe3Si and Fe; these elucidate the nanocrystallization in two stages. The first stage revealed the formation of DO3 nanocrystals and the second stage show evidence of a disordered Fe-rich interfacial region formed around the DO3 nanograins. Thus the cumulant analysis of EXAFS is sensitive to the different crystalline fraction arising from annealing at various temperatures.