Concurrent atomistic–continuum simulation of polycrystalline strontium titanate

Abstract

This paper presents the new development of a concurrent atomistic–continuum (CAC) method in simulation of the dynamic evolution of defects in polycrystalline polyatomic materials. The CAC method is based on a theoretical formulation that extends Kirkwood’s statistical mechanical theory of transport processes to a multiscale description of crystalline materials. It solves for both the deformation of lattice cells and the internal deformation within each lattice cell, making it a suitable method for simulations of polyatomic materials. The simulation results of this work demonstrate that CAC can simulate the nucleation of dislocations and cracks from atomistically resolved grain boundary (GB) regions and the subsequent propagation into coarsely meshed grain interiors in polycrystalline strontium titanate without the need of supplemental constitutive equations or additional numerical treatments. With a significantly reduced computational cost, CAC predicts not only the GB structures, but also the dynamic behaviour of dislocations, cracks and GBs, all of which are comparable with those obtained from atomic-level molecular dynamics simulations. Simulation results also show that dislocations tend to initiate from GBs and triple junctions. The angle between the slip planes and the GB planes plays a key role in determining the GB-dislocation reactions.

Keywords:

• grain boundaries
• polycrystalline
• dislocations
• multiscale modelling
• multiscale simulation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This material is based upon the work supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering [grant number DE-SC0006539]. The work of N.Z. was also supported in part by National Science Foundation under [grant number CMMI-1129976], [grant number CMMI-1233113].