液态纯铁微观结构的温度变化特性

利用液态金属高温X射线衍射仪对纯铁熔体的微观结构进行了研究, 获得了结构因子、双体分布函数、原子间最近邻距离以及配位数. 结果表明, 随着温度的升高, 结构因子和双体分布函数第一峰的高度逐渐降低; 原子间最近邻距离则先降低然后基本保持不变; 纯铁熔体的配位数和原子团相关半径在1600～1650 ℃的温度范围内有一个突变, 表明熔体中发生了结构转变; 对相关半径的物理意义进行了探讨.

Characteristic of Temperature-induced Change on the Microstructure of Liquid Pure Iron

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.