Nanocrystalline and amorphous cores

Nanocrystalline tapes are produced in two stages - by rapid cooling of the alloy, and then by treatment in a thermal and magnetic field of materials with an amorphous structure, for example FeCuNbSiB. During processing, a controlled process of fine-grained crystallization takes place - making it possible to control the functional properties of the final product. The obtained grain sizes are of the order of 20 nm and result from the addition of Cu and Nb. During the annealing process of the tape, Cu atoms - which hardly bind to Fe - impede the uncontrolled growth of the grains of the 20% Si-Fe crystal phase, as a result of which these grains are nanometric in size and have the property of orientation under the influence of an external magnetic field.

In amorphous tapes, FeSiB remains the commonly known chemical composition, with both chemical and topological disorder. This means that both the position and type of atoms in the environment, and the number of chemical bonds, their distances and angles they create, are different for each atom. Hence, Fe-based amorphous materials are also called metallic glasses.