Effect of Thermal Cycle on Liquid Structure of Pure Iron at just above Its Melting Point

摘要

The effect of thermal cycle on liquid structure of pure iron was investigated by means of theta-theta type liquid metal X-ray diffractometer. The increase of thermal cycle times results in the reduction of the atomic cluster size and its atomic numbers, the expansion of the disorder areas, and the increase of the disorder degree of the liquid pure iron. The first sharp diffraction peak (FSDP) or pre-peak is found in the structure factor curve of liquid pure iron, which means there is medium-range order (MRO) in this melt. The FSDP or pre-peak directly relates to the correlation of Fe-Fe atoms on the MRO scale. It is concluded that the body-centered cubic (BCC) crystal structure of the previous δ-Fe is partly kept in the liquid pure iron, and the liquid pure iron is a mixture of atomic clusters and disorder areas.