Recent advances in superplastic ceramics and ceramic composites

Superplasticity in ceramics and ceramic composites is reviewed. Deformation characteristics, and in particular the strain rate sensitivities in these materials, are discussed. From the strain rate sensitivity and grain size dependence, deformation mechanisms in these superplastic materials have been addressed. It appears that grain boundary sliding is the predominant deformation mechanism. Constitutive equations governing the superplastic flow in superplastic ceramics and ceramic composites are presented. Microstructural features in these materials, e.g. grain size and morphology, and glassy phases at grain boundaries, are described. Microstructure stability, and particularly, concurrent grain growth during superplastic deformation and its effect on superplastic elongation, is discussed. In this review, the superplastic properties and microstructures of some other advanced materials, e.g. intermetallics, metal matrix composites, and mechanically alloyed alloys, are also briefly reviewed and compared with those of superplastic ceramics. © 1991 The Institute of Metals and ASM International.