New understanding of nano-scale interstitial dislocation loops in BCC iron

Mechanisms for <100> interstitial dislocation loops to diffuse in BCC iron

The mobility of dislocation loops in materials is a principle factor in understanding the mechanical strength, and the evolution of microstructures due to deformation and radiation. In body-centered cubic (BCC) iron, the common belief is that <100> interstitial dislocation loops are immobile once formed. However, using self-adaptive accelerated molecular dynamics (SSAMD), a new diffusion mechanism has been discovered for <100> interstitial dislocation loops. The key aspect of the mechanism is the changing of the habit planes between the {100} plane and the {110} plane, which provides a path for the <100> loops to diffuse one-dimensionally. The migration behavior modeled with SSAMD is further confirmed by in-situ transmission electron microscopy (TEM) measurements, and represents a significant step for understanding the formation of <100> loop walls and the mechanical behavior of BCC Fe under irradiation.

The mobility of dislocation loops in materials is of key importance to understanding their deformation behavior. Here the authors using self-adaptive accelerated molecular dynamics show self-diffusion of <100> interstitial loops in body-centered cubic (BCC) iron by changing its habit plane as also confirmed by transmission electron microscopy (TEM) measurements.