Dislocation dynamics formulation for self-climb of dislocation loops by vacancy pipe diffusion

Abstract

It has been shown in experiments that self-climb of prismatic dislocation loops by pipe diffusion plays important roles in their dynamical behaviors, e.g., coarsening of prismatic loops upon annealing, as well as the physical and mechanical properties of materials with irradiation. In this paper, we show that this dislocation dynamics self-climb formulation that we derived in Ref.[1] is able to quantitatively describe the properties of self-climb of prismatic loops that were observed in experiments and atomistic simulations. This dislocation dynamics formulation applies to self-climb by pipe diffusion for any configurations of dislocations, and is able to recover the available models in the literature for rigid self-climb motion of small prismatic loops. We also present DDD implementation method of this selfclimb formulation. Simulations performed show evolution, translation and coalescence of prismatic loops as well as prismatic loops driven by an edge dislocation by self-climb motion and the elastic interaction between them. These results are in excellent agreement with available experimental and atomistic results. We have also performed systematic analyses of the behaviors of a prismatic loop under the elastic interaction with an infinite, straight edge dislocation by motions of self-climb and glide.

Phase field model for self-climb of prismatic dislocation loops by vacancy pipe diffusion

“…We validate our phase field model by numerical simulations and comparisons with the DDD simulation results obtained in Ref. [13] and available experimental observations. The rest of the paper is organized as follows.…”

“…In Ref. [13], a numerical implementation method of this self-climb formulation for discrete dislocation dynamics (DDD) was proposed, and simulations were performed on evolution, translation, coalescence and other self-climb motions of prismatic loops that are in excellent agreement with experimental and atomistic results. It has also been shown that this self-climb formulation is able to quantitatively explain the annihilation of prismatic loops with free surfaces by dislocation self-climb observed in molecular dynamics simulations [16] and self-healing of low angle grain boundaries by vacancy diffusion [17].…”

“…In this section, we briefly review the velocity formulation of dislocation self-climb by vacancy pipe diffusion established in Refs. [1,13].…”

“…At room temperature, the self-climb due to vacancy pipe diffusion along the dislocations is dominant in the dislocation climb process. When the climb force is not very large, the self-climb velocity is [1,13]…”

“…The self-climb motion is the dominant mechanism of prismatic loop motion and coalescence at not very high temperatures. Dislocation self-climb motion plays important roles in the properties of irradiated materials and has been an active research topic ever since it was first observed in 1960's [3,4,5,6,7,8,9,10,11,12,1,13,14,15]. In Ref.…”