This work concerns the study of soft iron-based magnetic materials. More specifically, concerning based iron amorphous materials, it will be done by combining structure and magnetic properties while acting on various parameters, by annealing to characterize the nanocrytallization. An experimental approach of magnetic properties is applied to the amorphous or nanocrystalline ultra soft materials evaluation of power losses, permeability as properties of the cycle of hysteresis. According to the scale of constraints and the nature of heat treatment (without magnetic field or magnetic field), it is induced an anisotropy which changes the magnetization properties. Thus, for ferromagnetic amorphous alloys, the anisotropy induced constraints is eliminated giving rise to a uniaxial anisotropy. FeBSi amorphous type materials can therefore, after introduction of copper (multiplication of germs) and niobium (growth inhibition), get nanocrystallized compositions of Fe73,5Cu1Nb3Si13,5B9 after annealing around of 500 - 600 °C
