Abstract: Using a hightemperature Xray diffractometer on liquid metals, the structure factors (SF), pair distribution functions (PDF), the nearest neighbor distances (NND) as well as the coordination number of pure iron melt at different temperatures were obtained. The experimental results show that with the increase of temperature the height of the first peak of SF and PDF of liquid pure iron becomes smaller gradually, but the NND becomes smaller first and then keeps constant basically. Both the coordination number and the correlation radius of atomic cluster of pure iron melt have a sudden change at the temperature range of 1600～1650 ℃, indicating a structural transformation. The physical meaning of the correlation radius rc was also discussed.

Key words: Pure iron, Melt, Liquid structure, Atomic cluster