On the role of long range internal stresses on grain nucleation during discontinuous recrystallization

TL;DR

This paper demonstrates how long-range elastic interactions significantly influence grain nucleation during discontinuous recrystallization, showing a transition to spontaneous nucleation driven by internal stresses.

Contribution

It introduces an analytical model highlighting the impact of long-range elastic interactions on nucleation, revealing a sharp transition to spontaneous nucleation without requiring critical nucleus size.

Findings

Long-range elastic interactions lower nucleation energy barriers.

A critical stress triggers a transition to spontaneous nucleation.

Model applicable to various crystalline materials with plastic anisotropy.

Abstract

The essential role of long range elastic interactions in recrystallization is demonstrated using a simple analytical model: pileup rearrangements following absorption of leading dislocations by a dislocation-free embryo provides an additional driving force that results in a drastic decrease of both the nucleation critical radius and the saddle point energy. A very sharp transition is evidenced, at which the saddle point totally disappears and nucleation becomes spontaneous. This transition occurs for a well defined critical stress corresponding to both a critical density of geometrically necessary dislocations and a critical strain, without invoking any critical nucleus size that may be reached with the help of some dislocation microstructure instability. The present model is illustrated here by the case of polycrystalline ice, but may apply to other crystalline material with significant plastic anisotropy, as Zircaloy for instance.