Energetics of formation process of a prismatic dislocation loop via the collision between two 1/2 loops in α-iron

Abstract

It has been proposed by Marian et al. [1] that a [001] interstitial-type dislocation loop can be formed in body-centered cubic iron via the collision between a 1/2[111] loop and 1/ 2[111] loop, which undergo one-dimensional glide diffusion, and the subsequent shear reaction. However, the formation of [001] loops through this reaction has not been reproduced by other works even though the two 1/2<111> loops collided with each other. In the present paper, the origin of the difficulty in this reaction is discussed within the framework of isotropic elasticity theory. The sign of the driving force for the reaction is heavily dependent on the reaction path. The two 1/2<111> loops colliding to form a [110] junction can transform to a single [001] loop when a shear loop generated within the 1/2[111] loop propagates in sync with the other shear loop within the 1/ 2[111] loop. However, unsynchronized motion of the two shear loops significantly suppresses the propagation of the shear loops, which might be caused by the thermal fluctuation at finite temperatures. This will be one of the origins of the difficulty in the formation of [001] loops through the collision between the two 1/2<111> loops.