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在时效过程中,扩散现象起着极其重要的作用。扩散速度愈大,原子愈能迅速到达第二相晶核出现及成长的地点,时效过程也就进行得愈快。 费克的扩散定理是基于假定物质是从浓度较高的区域移向浓度较低的区域。康诺别也夫斯基、杰林盖尔等人较晚的著作证明,在扩散过程中起更重要作用的并不是浓度梯度,而是活度梯度。 杰林盖尔推导出的有效扩散系数为,
In the aging process, the phenomenon of proliferation plays an extremely important role. The greater the rate of diffusion, the more quickly the atom reaches the second phase of nucleation and growth of the site, the aging process will be carried out faster. Fick’s diffusion theorem is based on the assumption that substances move from areas of higher concentration to areas of lower concentration. Later work by Conorbevsky and Jelengel proved that concentration is not a concentration but a activity gradient, which plays a more important role in the diffusion process. The effective diffusion coefficient Derlinger derives from is,