Change in elastic properties of eutectic alloys under conditions of superplastic deformation

Abstract

In this study, experimental data have been obtained which reveal taking place of complex physical processes under conditions of the structural superplasticity not only in the grain boundary, as it is commonly believed, but also in the grain body. It was established for the first time that superplastic deformation of the eutectic alloys is accompanied by significant changes in their Young’s moduli. It was demonstrated that under superplastic deformation the observed changes of the elastic properties of the eutectic Sn–38wt%Pb alloy under study are caused mainly by the decomposition of supersaturated solid solutions on the basis of the alloy components and the relaxation of internal stresses. It was also found that the viscous dislocation–diffusion non-conservative flow is actively developing in the eutectic alloys under conditions of superplasticity, in contrast to the existing ideas about grain boundary sliding as the main mechanism of the matter transport. The experimental results obtained are important for the deeper understanding of the physical nature of the structural superplasticity effect.