Nanocrystalline magnetically soft materials were discovered by Yoshizawa, Yamauchi and Oguma in 1986 [1, 2]. This was preceded by numerous research and development of amorphous magnetically soft materials, beginning in 1960. In order to obtain an amorphous structure, ultrafast quenching of a metallic melt with a cooling rate of about 106 K/s is used. Under industrial conditions, amorphous tape with a thickness of about 20 μm is produced using the flat jet method [3]. In scientific research, the amorphous Fe-B alloy is widely used in which boron acts as an element that promotes amorphization. For industrial purposes the Fe-Si-B alloy [4] is more suitable, in which silicon is additionally introduced to increase the crystallization temperature and reduce the coercive force.
The study of multicomponent melts shows that the structures of liquid and solid states are interrelated. The most homogeneous structure has the melt heated above the critical temperature, which corresponds to the temperature of structural transformations. Amorphous precursor obtained from homogeneous melt has greater ductility and hardness, higher enthalpy of crystallization. After nanocrystallization of the amorphous precursor obtained from the superheated melt, a material with higher permeability was obtained, which can be attributed to the increased proportion of small nanocrystals of about 2 nm.
Production of magnetic systems from nanocrystalline materials can be divided into several technological operations [5]. The initial operation is the melting of an alloy of a given chemical composition. This is followed by superfast quenching of the melt to form an amorphous precursor in the form of a ribbon with a thickness of about 20 nm. Thermal processing of the amorphous precursor should ensure the formation of a nanocrystalline structure with a guaranteed level of magnetic properties. As a rule, a magnetic curcuit or core is made from the amorphous precursor beforehand. In this paper the physical properties of nanocrystalline alloys in the liquid state, the influence of chemical composition on the nanocrystallization process, magnetic properties, in particular magnetic losses, and the application of magnetically soft nanocrystalline alloys, mainly for power electronics, are discussed.