Boundary Diffusion With a Strong Kinetic Effect on Eutectic Growth

Abstract

The atomic attachment pathway for boundary diffusion is different from that of volume diffusion, thus leading to a stronger kinetic effect. However, it remains challenging to quantitatively determine the kinetic part from the total undercooling. In this article, the kinetic contribution is incorporated into the boundary diffusion model, and the relationships between the growth rate, interphase spacing, and undercooling are obtained, by which the kinetic effect is examined. Moreover, a polymeric eutectic system composed of polyethylene glycol 6000 and 1, 3, 5 - trioxane was chosen to check the kinetic undercooling during the phase transition. This showed that the eutectic grows via boundary diffusion and that kinetic undercooling takes up a majority of the total driving force. Our results can provide in-depth insight into the kinetic contribution during a boundary-diffusion controlled eutectic transformation.