Nanocrystalline alloys are made of iron, silicon, boron and a small amount of copper, niobium and other elements through a rapid cooling process to form an amorphous alloy, and then undergo a highly controlled annealing process to form a nano-scale microcrystalline and amorphous mixed structure. Material. The crystallite diameter of this material is 10-20nm, which is dispersed and distributed on the amorphous matrix. It is called microcrystalline, nanocrystalline material or nanocrystalline material.