Superplasticity from viscous flow in high Pb ternary alloy

This work identifies a new superplastic alloy and proposes the responsible phenomenological model for superplastic flow based on mechanical characterization and microstructural observations. 85Pb-10Sb-5Sn exhibited unusual superplastic behavior in that it requires high homologous temperatures to experience superplastic elongations. A characteristic temperature (TGBS), where grain boundary sliding becomes dominant, was found, which differentiates superplastic from non-superplastic flow. The microstructure study revealed that localized viscous flow of the regions at certain grain boundaries and shear interfaces, followed by formation and elongation of amorphous-induced zones, is responsible for superplastic elongations.