Assessment of meta-atom scheme for nucleation of dislocation loops in TWIP steel

Abstract

We use atomistic calculations to explore the process of homogeneous nucleation of dislocation loops in TWIP steel with the nudged-elastic-band method and meta-atom interatomic potential. Energy barriers to the nucleation process have been estimated at different applied shear stresses, and an atomistically informed nucleation model is fitted to the results for both Shockley and twinning dislocation loops. Besides exhibiting excellent agreement with the direct atomistic results, the nucleation model also provides the critical size of the dislocation loop. Comparison of the critical loop diameters with the intrinsic spatial scale of the meta-atom potential reveals that the loop nucleation is sensitive to the local compositional heterogeneity. As a result, the simulation results obtained with a meta-atom potential are shown to require careful interpretation in terms of their statistical ramifications.