Improved continuous precipitation kinetics and tensile properties of extruded AZ80 alloy through {10-12} twin formation

초록

This study investigates the effect of {10-12} deformation twins on the continuous precipitation behavior of an extruded Mg-8.0Al- 0.5Zn-0.2Mn (AZ80) alloy during aging. The extruded AZ80 alloy is compressed along the transverse direction to introduce {10-12} twins, followed by an aging treatment at 300 degrees C. The extruded material exhibits a twin-free microstructure with low internal strain energy, whereas the pre-twinned material possesses abundant {10-12} twins and has high internal strain energy. The aging results reveal that the peak-aging time of the pre-twinned material (1 h) is one-eighth of that of the extruded material (8 h). Although Mg17Al12 continuous precipitates (CPs) are observed in both the peak-aged materials, these CPs are much smaller and more densely distributed in the pre-twinned material despite the significantly shorter aging time. The CPs size in the peak-aged materials increases in the following order: twinned region in the pre-twinned material (0.47 mu m) < residual matrix region in the pre-twinned material (1.71 <mu>m) < matrix region in the extruded material (2.55 <mu>m). Moreover, the CPs number density in the twinned region of the pre-twinned material is approximately 11 times higher than that in the matrix region of the extruded material. The peak-aged pre-twinned material exhibits significantly higher tensile strength and ductility than the peak-aged extruded material. These results demonstrate that the formation of {10-12} twins in the extruded AZ80 alloy substantially accelerates the static precipitation of CPs during aging at 300 degrees C and improves the tensile properties of the peak-aged material. (c) 2023 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

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