双层密排六方结构晶体的结构因子计算

On Structural Factor and Forbidden Reflection Planes in Double Hexagonal-Close-Packed Crystal

摘要:

双层密排六方结构（dhcp）是密排六方结构的一种变体，常常出现于一些金属极端条件下的相变过程。根据电子衍射理论，计算了这种相的结构因子并得出了其消光规律。即：l为奇数：或者2h＋k=3n，l=4n＋2（n为任意整数）。与镁合金中出现的dhcp相的电子衍射花样对比，理论预测和实际情况符合很好。

Abstract:

Double hexagonal-close-packed (dhcp) crystal structure is a variant of hexagonal-close-packed (hcp). It is always found in phase transformation process at extreme conditions, i. e., high temperature and pressure. In this paper, structural factor of the dhcp was calculated on basis of the electron diffraction theory and the forbidden reflection law was discussed. If l is odd or the condition, 2h+k=3n, l=4n+2 (n a random integer.), is met, the crystal plane (hkl) will be forbidden to reflect. This predicted result is good agreement with the diffraction patterns from an investigation of phase transformations in commercial magnesium alloy.