Study of non-linear kinetics of order-disorder transition with compositional modulation

用改进后的非线性动力学方程研究了有序-无序相变过程中的成分调制动力学。对于有序相的不稳定性，对方程进行了求解。从溶液的特征可以看出，在某些非化学计量比的合金中，有序化倾向于增强成分调制。为了证实这一猜想，用X射线衍射仪和电子显微镜对Fe-Al合金的有序化和相分离过程进行了深入的研究。观察到DO_3和GT；相的调幅分解和析出行为强烈依赖于反相区的初始尺寸，这与理论上的预期一致。用场离子显微镜在原子尺度上观察了CuPT中的异相有序化过程，发现有序域的生长动力学与有序域内的有序度和有序域的大小有关。用另一个简单的方程成功地解释了这一现象。首次在Fe-Mo合金中发现了电子辐照促进的调幅分解。这也可以用辐射引入的点缺陷的非线性效应来很好地解释。从上述理论和实验结果可以得出结论，元素过程之间的关联在具有成分调制的有序-无序转变中起着相当重要的作用，它对应于动力学方程中的非线性项。

Kinetics of the order-disorder transition with compositional modulation was studied with the non-linear kinetic equation which had been improved by the present workers. The equation was solved for the instability of an order phase. It was expected from the features of the solutions that in some off.stoichiometric alloys an ordering tends to enhance compositional modulation. In order to confirm the conjecture, the process of ordering and phase separation in Fe-Al alloys was investigated intensively by X-ray diffraction and electron microscopy. It was observed that the behaviors of spinodal decomposition and precipitation in <DO_3> phase depend strongly upon the initial size of antiphase domains in agreement with the theoretical expectation. The heterogeneous ordering process in CuPt was observed in atomic scale with a field-ion microscope, and the growth kinetics of order domains was found to be correlated with the degree of order within the domains and the domain size. The phenomenon was explained successfully with another simple equation. A spinodal decomposition enhanced by electron irradiation was first recognized in an Fe-Mo alloy. This was also explained well in terms of a non-linear effect of point-defects introduced by irradiation. From the theoretical and the experimental results mentioned above, it is concluded that the correlation between elemental processes, which corresponds to a non-linear term in a kinetic equation, plays a quite important role in the order-disorder transition with compositional modulation.