On stress-assisted boundary migration during recrystallization

TL;DR

This paper explores how local stress anisotropy influences boundary migration during recrystallization in high-purity aluminum, using in situ strain and stress measurements.

Contribution

It provides detailed insights into the stress-driven mechanisms of boundary migration, emphasizing the role of residual stress patterns without shear-coupled motion.

Findings

Residual strains of ~10^{-3} within recrystallizing grains.

Boundary migration correlates with local residual strain patterns.

No shear-coupled motion observed during boundary migration.

Abstract

This study investigates the boundary migration mechanisms near the sample surface of recrystallizing grains in high-purity Al subjected to cryogenic rolling. Local strain and stress tensors were characterized during \textit{in situ} annealing by combining high-resolution electron backscatter diffraction with microstructure-based digital image correlation strain analysis. The results reveal local residual strains on the order of $10^{-3}$ within the recrystallizing grain, with values several times higher in the adjacent deformed matrix. The residual stresses in recrystallizing grains are a passive response to those developed within the surrounding deformed grains; the latter being strongly influenced by the local geometry and characteristics of dislocation boundaries, as well as by constraints imposed by neighboring grains. No evidence of shear-coupled motion was observed during the recrystallization boundary migration, despite the presence of shear stress across the boundary. In contrast, detailed analysis of the principal strain components reveals a clear correlation between residual strain patterns and boundary migration directions. These findings indicate that recrystallization boundary migration is modulated by the anisotropy of the local internal stress state.