The Unit Cell Reconstruction and Related Thermal Activation Process within Coherent Twin Boundary Migration in Magnesium

TL;DR

This paper investigates the atomic-level mechanisms of coherent twin boundary migration in magnesium, revealing a stochastic unit cell reconstruction process driven by thermal fluctuations and detailing the associated activation parameters.

Contribution

It introduces the concept of independent unit cell reconstruction as the core migration process and elucidates the thermal activation mechanisms involved.

Findings

Identification of the elementary migration process as unit cell reconstruction

Atomistic pathways show stochastic response to thermal fluctuations

Quantitative parameters for thermal activation process are reported

Abstract

By analyzing the interface defect loop nucleation and the interface disconnection expansion in dynamic simulations, the elementary migration process of coherent twin boundary of magnesium is identified to be independent unit cell reconstruction. The atomistic pathways of the unit cell reconstruction prove their collective behavior as a stochastic response to thermal fluctuation at a stressed state, and also the onset mechanism of interface disconnection gliding: predominant pure-shuffle basal-prismatic transformation along with atomistic shear movements. The athermal shear strength, the migration barrier, the critical length of disconnection dipole and other parameters characterizing the thermal activation process are reported.