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

利用现有工作者改进的非线性动力学方程，研究了含组分调制的有序-无序转变动力学。求解了阶相的不稳定性方程。从解的特征可以预料到。化学计量合金的有序化倾向于增强成分调制。为了证实这一猜想，利用x射线衍射和电子显微镜对Fe-Al合金的有序和相分离过程进行了深入的研究。结果表明，<DO_3>相的旋量分解和析出行为与反相畴的初始尺寸有很大关系，与理论预测一致。利用场离子显微镜在原子尺度上观察了CuPt的非均相有序过程，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。在Fe-Mo合金中首次发现了电子辐照增强的旋多分解现象。辐照引起的点缺陷的非线性效应也很好地解释了这一点。从上述理论和实验结果可以看出，元素过程之间的相关性，对应于动力学方程中的一个非线性项，在有组分调制的有序-无序转变中起着相当重要的作用。

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.