Initial process of continuous dynamic recrystallization in a superplastic Al-Mg-Mn alloy

Abstract

Microstructural evolution during region III deformation (T=723 K, ϵ=10-1 s-1) in a superplastic Al-Mg-Mn alloy (ALNOVI-U) was investigated. Surface makers drawn by focused ion beams (FIB) and internal observation by the electron back-scattered diffraction (EBSD) method were used for surface studies and internal studies, respectively. The surface markers clarified that both grain boundary sliding and dislocation activity significantly contributed for deformation. In the EBSD studies, formation of new low-angle boundaries (LABs) was observed at core/mantle boundaries and in core regions. The new LABs were formed by dynamic recovery of dislocation walls; it is the initial process of continuous dynamic recrystallization in region III superplasticity.