Incorporating point defect generation due to jog formation into the vector density-based continuum dislocation dynamics approach

TL;DR

This paper extends a continuum dislocation dynamics model by incorporating point defect generation from jog formation, revealing effects on material hardening and dislocation density during plastic deformation.

Contribution

It introduces a coupled model of point defect generation and dislocation dynamics, including stress effects and energy dissipation mechanisms, advancing the understanding of defect-dislocation interactions.

Findings

Vacancy and interstitial generation are asymmetric due to different formation energies.

Coupling point defect generation increases dislocation density and hardening rate.

The model successfully simulates defect transport and its impact on plastic deformation.

Abstract

During plastic deformation of crystalline materials, point defects such as vacancies and interstitials are generated by jogs on moving dislocations. A detailed model for jog formation and transport during plastic deformation was developed within the vector density-based continuum dislocation dynamics framework (Lin and El-Azab, 2020; Xia and El-Azab, 2015). As a part of this model, point defect generation associated with jog transport was formulated in terms of the volume change due to the non-conservative motion of jogs. Balance equations for the vacancies and interstitials including their rate of generation due to jog transport were also formulated. A two-way coupling between point defects and dislocation dynamics was then completed by including the stress contributed by the eigen-strain of point defects. A jog drag stress was further introduced into the mobility law of dislocations to account for the energy dissipation during point defects generation. A number of test problems and a fully coupled simulation of dislocation dynamics and point defect generation and diffusion were performed. The results show that there is an asymmetry of vacancy and interstitial generation due to the different formation energies of the two types of defects. The results also show that a higher hardening rate and a higher dislocation density are obtained when the point defect generation mechanism is coupled to dislocation dynamics.