到目前为止,有序合金扩散理论尚存在两个重要的问题有待突破.一是如何正确理解原子的热扩散运动与合金中原子有序排列之间的矛盾;二是能否将扩散系数以外的其它理论参量与原子跳跃迁移的相关实验测量联系起来.为了解决这些问题,作者建议使用原子在不同格点的停留时间差异来表达合金的有序度参量.当原子在反结构晶格位置的平均停留时间很短时,原子完全可能以最近邻跳跃的方式在有序合金中迁移而不破坏原子的长程有序排列.以B2-NiGa有序合金为例,根据Ni原子格点停留时间的赝弹性中子散射实验测定,作者计算了1403 K温度时B2-NiCa合金的有序度为78.9%.

There are seemly two important points in need of breakthrough for understanding atomic diffusion in ordered alloys. The one is how the long-range order of atoms can be restored when atomic diffusion takes place, and the other is how the theoretical expressions in their present form, more than one self-diffusion coefficient parameter, can be applied to experimental results directly. To solve these problems, we derived the expression of the orders degree of atomic arrangements by the difference in residence times. It is considered that atoms migrate properly in the ordered alloy via nearest-neighbor jumps without disturbing the ordered arrangements, provided that the average residence time of the atom on the antistructure site should be very short. The degree of order R_(Ni) of Ni atoms in B2-NiGa alloy is expected to be 78.9% at 1403 K according to the calculations from the measurement of residence time for Ni atoms in B2-NiGa.