Structure-dependent grain boundary deformation and fracture at high temperatures

This paper gives an overview of structure-dependent intergranular deformation and fracture of metallic bicrystals and polycrystals at high temperatures. Structure-dependent grain boundary sliding and migration during high temperature deformation are discussed in connection with grain boundary structural change by the interaction with lattice dislocations and by intrinsic and extrinsic grain boundary structural transformation due to temperature and segregation, respectively. “Grain boundary engineering” for improvement in creep strength, development of superplasticity and control of oxidation-assisted intergranular brittleness are introduced which were successfully achieved by engineering the grain boundary microstructures characterized by the grain boundary character distribution (GBCD), the grain boundary connectivity and grain size.