Evidence of cooperative grain boundary sliding in superplastically deformed γ-TiAl

Abstract

A study of the prepolished surface of γ-TiAl specimens superplastically deformed in tension showed evidence of macroscopic surfaces at which grain boundary sliding occurs. In a scanning electron microscope these surfaces are observed as black bands on the deformed surface because of the difference in the appearance of these bands and grain regions situated in between these bands. It has been suggested that cooperative grain boundary sliding, i.e., sliding of grain groups, occurs during superplastic deformation, giving rise to these bands.