Comparison of mechanisms of plasticity enhancement at the superconducting transition

Abstract

The mechanisms of the plasticity enhancement at the N-S transition are considered, based on a comparison of the dependence of this effect on the concentration of defects limiting the dislocation mobility, which, as is shown, is different for competing dynamic models. A method is suggested for determining the role of quasistatic effects, arising due to the inhomogeneity of the dislocation structure of superconductors, in the plasticity enhancement at the N-S transition.

The Effect of the Superconducting Transition on Plastic Deformation of Ultrafine‐Grained Aluminum

“…The acceleration of a dislocation moving between two consecutive pinned configurations (over the mean free path, L $ L) was considered in reference. [9] It was shown that, as distinct from the results of reference, [8] for large concentration of pinning points (L < 10 À7 m) the magnitude of Ds NS is to decrease with increasing concentration of the pinning points. A statistical analysis of the role of the inertia effects in thermally activated dislocation motion [10] led to similar conclusions regarding the dependence of Ds NS on the non-dimensional concentration of the pinning points, C ¼ aS À1/2 , where a is the lattice parameter and S is the average area per pinning point.…”

“…The current models that describe the influence of the transition from the superconducting (S) to the normal (N) state [4][5][6][7] consider the role of the electron drag in the thermally activated overcoming of localized obstacles by moving dislocations, which also involves an effect of the dislocation inertia. [8,9] Under external load, a dislocation, which possesses an effective mass, breaks away from point-like pinning points in a thermally assisted process and moves ahead until it meets a next obstacle. Due to the inertia, the dislocation overshoots the static equilibrium configuration.…”

Uncovering the inertia of dislocation motion and negative mechanical response in crystals

“…However, it should be pointed out that, the inertia was deduced from the mechanical response, rather than being directly observed, and there also existed other interpretations that are not related to inertia, such as the changes in electron drag 15 , 19 , obstacle strength 20 , 21 and mobile dislocation density 22 when entering the superconducting state. Efforts have also been made by Indenbom and Estrin to distinguish between different dynamic models of plasticity enhancement 23 . These experimental results and different theoretical interpretations were summarized and reviewed by Kostorz 24 .…”