THEORY OF THE ENHANCEMENT FACTORS OF SOLUTE DIFFUSION IN DILUTE BCC SOLID-SOLUTIONS

The enhancement factors for the solute diffusion in dilute b.c.c. allo ys are discussed on the lines of two approaches. One of them is based on the Taylor's expansion series of activation energy and pre-exponent ial factor on concentration. The convergency of these series is studie d. The second approach is formulated in the framework of the statistic al theory. The comparative analyses of these two ways for the explanat ion of the enhancement of diffusion is carried out. The concentration dependencies of jump frequencies are investigated for V-Zr dilute soli d solution as an example. It is shown that these dependencies are conn ected with the changes of the migration energy E(m)(c) as well as with the changes of the frequencies of vibrations. Different mechanisms th at are possible for the explanation of the enhancement of D(c) are dis cussed.