PNNL

Abstract

Molecular dynamics and transmission electron microscopy (TEM) are employed to study the formation and evolution of interstitial dislocation loops due to nearby growing helium bubbles. The study reveals a novel mechanism that suppresses further formation of loops. Mass transport of self- interstitial atoms between the bubbles is observed, followed by the loop formation, resulting in a loop- bubble complex in which the Burgers vector may rotate between and 1/2. Such a complex can absorb free loops, effectively influencing the evolution of loop number density. These results provide new understanding of loop-bubble complex formation and saturation of the loop density under a continuous helium implantation in materials.