THEORY OF GRAIN-BOUNDARY MOTION IN THE PRESENCE OF MOBILE PARTICLES

A theory of grain boundary motion in the presence of mobile particles is put forward. It is shown that the boundary-particle-interaction lea ds to a hysteresis in the velocity-driving relationship. The extent of the hysteresis depends on particle mobility, which is very sensitive to particle size. The effect of particles is discussed for planar and curved boundaries as well as volume particle distributions. The theory accounts for a smaller limiting grain size during grain growth than p redicted by Zener drag. The concept can be generalized to include all kinds of mobile obstacles for boundary migration. In such cases not th e distribution-of obstacle spacing rather the distribution of obstacle mobilities will control microstructure evolution.