AB合金有序化过程的动力学(Ⅰ)

由原子在点阵中扩散的反应率过程理论,在最近邻近似下,计算了AB合金的长程有序化动力学及长程序为零时的短程有序化动力学。所得结果与前人的实验结论及计算结果相比定性地符合,定量地接近。长程有序化动力学的计算表明,有序化过程存在有孕育期,有c-曲线形式的转变曲线,s近似与exp{-αt²}正比,算得的平衡有序度与前人计算结果相近。长程序为零时的短程有序化动力学的计算表明,σ近似与exp{-βt}正比,此时有序化速率甚快,以致在最快的淬火速率下,样品中也必然存在有一定的短程序,所得的平衡短程序值也符合前人的计算结果。本文是作为继续计算短程有序化动力学的准备及基础。

ON THE KINETICS OF ORDERING IN AB ALLOY

According to the theory of the rate process of diffusion of atoms in lattice, the kinetics of long-range ordering and short-range ordering under the condition of zero long-range order in the nearest neighbour approximation has been investigated. The results obtained agree qualitatively with and quantitatively similar to the conclusions derived from the past experiments and calculations. The results obtained from the calculations of the kinetics of long-range ordering show that the process of ordering requires an induction period, the transformation curves have the form of C-curves and the degree of longe-range order depends upon time in the form of exp {-αt²} -approximately. The equilibrium values of the degree of long-range order obtained are very similar to those of the past workers. The results obtained from the calculations of the kinetics of short-range ordering in the condition of zero long-range order depends upon time in the form of exp {-βt} approximately, and the rate of ordering is so quick, that even with the fastest quenching a certain degree of short-range order exists in the specimen. The equilibrium values of the degree of short-range order also agree with the results obtained in the past.