High-temperature intergranular diffusion
Intergranular diffusion in polycrystalline materials

A transition temperature $(T_C)$ delineates two types of grain boundary behavior as a function of temperature (intergranular sliding; migration and diffusion). This transition is accompanied by the appearance, at high temperature, of strong intergranular disorder, without loss of crystallinity. To understand the relationship between transition temperature and joint energy, we need to define two types of intergranular order