Preparation of nanocrystalline material for amorphous external layer

The invention relates to a preparation method for a nano-crystalline material, in particular to a preparation method for an amorphous exoexine nano-crystalline material. The key points are as follows: treatment is carried out on a amorphous material by using joule heat in flowing gas; due to the passing of continuous current, the temperature of the amorphous material is increased continuously, and after the temperature reaches the nano-crystallization temperature, nano-crystallization is carried out on the material; under the effect of the flowing gas of the surface layer, large amount of heat is taken away, the temperature cannot reach the nano-crystallization temperature, so the material is not nano-crystallized and is still in the amorphous state; therefore, the amorphous exoexine nano-crystalline material is formed. The invention has compact preparation structure, can combine the advantages of two types of materials into one body and also can prepare the material with excellent performance and high cost p