Magnetic properties and amorphous-to-nanocrystalline transformation by thermal treatments in Fe84.3Si4P3B8Cu0.7 amorphous thin films

Thin films of nominal composition Fe84.3Si4P3B8Cu0.7 have been prepared by sputtering from ribbons of the same alloy. Their microstructure has been studied by means of X-ray diffraction, differential scanning calorimetry and transmission electron microscopy, and reveals a partly amorphous state in the as-prepared samples. Their magnetic properties are soft and comparable to those measured on rapidly quenched ribbons. After annealing in furnace at temperatures up to 400 °C, their soft magnetic properties are improved thanks to the development of a fully nanocrystalline state. Annealing at higher temperature causes the coarsening of the α-Fe like grains, the development of hard magnetic phases and an increase of the coercive field.