Effect of solid solution addition on the dislocation emission in aluminum alloys
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O R I G I NA L PA P E R
Siwei Ren · Jia Li · Qihong Fang · Hui Feng
Effect of solid solution addition on the dislocation emission in aluminum alloys
Received: 8 February 2020 / Revised: 18 June 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Solid solution strengthening plays a key role in the strength increasing of alloying metals, due to that a solid solution of alloying element causes lattice distortion to a certain extent. In the paper, the effect of solid solution magnesium additions on the edge dislocation emission from a blunted crack tip in aluminum alloys is investigated. The critical stress intensity factor for the dislocation emission considering different magnesium solute concentrations is analyzed under the mode I and mode II loading conditions. The results show that within a certain concentration range the magnesium solute concentration does affect dislocation emission, although the influence appears not very strong. The critical stress intensity factor for the dislocation emission decreases with the increment of solute concentration. This means that relatively increasing the solute concentration can promote the dislocation emission, cause effective blunting of cracks and thus improve the fracture toughness of materials.
1 Introduction The dislocation, in the materials science, is an internal microscopic defect in crystalline materials and can also be expressed as the locally irregular arrangement of atoms. The dislocation emission from crack tips is one of the most basic processes to understand the ductile-brittle behavior of crystalline materials [1]. The critical stress intensity factor (SIF) is the main indicator to research the dislocation emission in previous studies [2–4], and in those studies, the crack tip is assumed to be sharp, which is a situation not proved by experiments [5]. The real crack in materials is always of finite length, and the curvature radius of the crack tip is never small enough to be zero [6,7]. During the last several decades, the emission of dislocation has been studied in depth. Fang et al. [8] studied the dislocation emission from an elliptically blunted crack tip considering the surface effects. They found that the impact of surface stress is remarkable for nanoscale blunted cracks. Zeng et al. [9] investigated the effect of thermal activation energy on the dislocation emission from an elliptically blunted crack tip. Their results show that the dislocation emission becomes easier at higher temperature. In materials, there are still many complex factors that influence the dislocation emission due to the existence of microstructures, such as grain boundaries [10–13], cavities [14], rotational deformations [15–17], solute atoms [18,19], and so on. The solid solution strengthening, which is the result of the interaction between solute atoms and dislocations, has been widely studied for a long time. The Fleischer model [20], Labusch theory [21], and Suzuki theory [22] are the mature classical theoretical models for studying the obstruction
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