A REVIEW ON GRAIN BOUNDARY EFFECTS IN SUPERPLASTICITY

Since superplasticity wasdiscovered in 1934, muchattention has been paid to its special deformation mechanisms. In thispaper, with the investigation on grain boundaries being taken as themain thread, some newdevelopments are summarized from a viewpoint of mechanics, including the modelsbased on the grain boundary topological structure, statistical law and energydissipation theory. Superplastic intergranular fracture due to the grainboundary void damage and relationships between grain boundary structurechanges and macroscopic rate-sensitivity are addressed. Typical numericalmodels for superplastic deformation simulations are enumerated, withconsiderations of grain boundary effects. Some importantexperimental methods measuring the grain boundary sliding are reviewed anddiscussed. Finally, we suggest some future directions insuperplasticity, including multi-scale coupled superplastic mechanics,applications of superplastic properties in material preparations andSPF/DB fabrication process.