Dislocation configuration evolution during extension twinning and its influence on precipitation behavior in AZ80 wrought magnesium alloy

Thermomechanical treatment T10 (extension twinning + aging treatment) can largely enhance the precipitation strengthening effect of magnesium alloys. In this study, dislocation structure evolution and precipitation behavior during T10 treatment of an AZ80 extruded bar were analyzed mainly by two-beam diffraction in TEM. At a compressive strain of 1% in the extrusion direction (ED), a typical dislocation configuration, including basal I 1 stacking faults (SFs) and < c + a > dislocations, has been established in extension twins. As the strain reaches 7%, the volume fraction of extension twins increases to more than 90% at which point high dense I-1 SFs and < c + a > dislocations occur. After aging for 2 h at 150(degrees)C for the 7% strained sample, masses of basal I-1 SFs and < c + a > dislocations remain in the extension twins and can act as effective nucleation sites and solute fast-diffusion channels for continuous precipitates. Consequently, the precipitates in extension twins become highly dense.(c) 2021 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing University

Automated summary

The study analyzed the influence of thermomechanical treatment T10 on the dislocation structure and precipitation behavior in magnesium alloys, and found that T10 treatment can significantly enhance the strengthening effect of magnesium alloys. This is achieved by forming high-density basal I-1 stacking faults and < c + a > dislocations as nucleation sites and fast diffusion channels for continuous precipitates in extension twins.