The effect of temperature and strain accumulation on the superplastic deformation behavior of an Al-Cu-Zr alloy

Abstract

The effects of temperature and strain accumulation on the superplastic deformation behavior of an Al-Cu-Zr alloy have been studied by performing a series of load relaxation tests at the various strain levels. The overall flow curves were then analyzed within the framework of a recently proposed internal variable theory for structural superplasticity. The overall flow curves were separated into two parts according to their respective physical mechanisms, viz. the grain boundary sliding (GBS) and the accommodating dislocation glide (GMD) processes, contrary to the conventional approach using a single power law relation. The microstructural evolutions during the superplastic deformation have been observed by using a transmission electron microscope. A small and stable grained microstructure was found to form completely by a dynamic recrystallization at the early stage of deformation. The GBS curve could be described as a viscous now signified with the power index value of M(g)approximate to 0.5 irrespective of the temperature and strain increment for this alloy.