Microstructural evolution during dynamic recrystallization in bicrystals and polycrystalline materials

Dynamic recrystallization (DRX) processes were studied in not only polycrystals including intermetallics, but also bicrystals. It can be clarified that the role of grain boundary sliding is very important in the formation of new grains as well as the progress of necklace DRX. Grain boundary sliding can introduce high local strains along grain boundaries, leading to the serration and the formation of new grains by bulging out. Bulging under hot deformation can take place much easier than that for static conditions. Successive strand of the necklace structure can be developed according to the same process because grain boundary sliding takes place predominantly in the region of fine grained necklace structure. It is concluded that hot deformation of some metallic materials can be controlled by DRX assisted by grain boundary sliding. On the other hand, necklace DRX takes place in intermetallics and results in the evolution of finer grains along grain boundaries, leading to the appearance of high ductility due to superplastic now. Hot deformation of intermetallics is considered to be controlled by grain boundary sliding assisted by DRX.