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Deformation-induced dynamic precipitation of 14H-LPSO structure and its effect on dynamic recrystallization in hot-extruded Mg-Y-Zn alloys
International Journal of Plasticity ( IF 9.8 ) Pub Date : 2023-02-25 , DOI: 10.1016/j.ijplas.2023.103573
Wei Liu, Yuhong Zhao, Yuntao Zhang, Chuan Shuai, Liwen Chen, Zhiquan Huang, Hua Hou

Understanding dynamic precipitation in thermo-mechanical processing can shed light on the manufacturing of high-performance Mg-based alloys. This study investigates the dynamic precipitation of long-period stacking order (LPSO) phase with 14H structure and its effect on dynamic recrystallization (DRX) in the hot-extruded Mg98.5Y1Zn0.5, Mg97Y2Zn1 and Mg94Y4Zn2 (at. %) alloys. First, the simultaneous increase of Y and Zn atoms not only promotes the formation of interdendritic block 18R-LPSO phases during solidification but also facilitates the dynamic precipitation of intragranular lamellar and thin 14H-LPSO phases in coarse non-DRX and fine DRX grains, respectively, during hot extrusion. Second, the increased block 18R volume fraction and lamellar 14H number density significantly delays DRX. However, as the deformation strain increases, broken 18R fragments accelerate the DRX particle-stimulated nucleation (PSN) mechanism and fluctuant α-Mg/18R interfaces initiate the discontinuous DRX mechanism. In particular, the deformation kinking and dissolving of lamellar 14H activate the continuous DRX mechanism. Finally, the mechanical strength increases but ductility decreases with increasing the content of Y and Zn atoms for the hot-extruded Mg-Y-Zn alloys. The high strength of the hot-extruded Mg94Y4Zn2 alloy is attributed to fine DRX grain size, strong un-DRX grains, major block 18R and lamellar/thin 14H phases, and deformation kinking, while the high ductility of the hot-extruded Mg98.5Y1Zn0.5 alloy is responsible for large DRX volume fraction, high activity of deformation twins, and easy mobility of basal slip.



中文翻译:

变形诱导的 14H-LPSO 结构动态析出及其对热挤压 Mg-Y-Zn 合金动态再结晶的影响

了解热机械加工中的动态析出可以阐明高性能镁基合金的制造。本研究研究了热挤压 Mg 98.5 Y 1 Zn 0.5、Mg 97 Y 2 Zn 1和 Mg 94 Y中具有 14H 结构的长周期堆垛有序 (LPSO) 相的动态析出及其对动态再结晶 (DRX) 的影响42(at. %) 合金。首先,Y 和 Zn 原子的同时增加不仅促进了凝固过程中枝晶间块状 18R-LPSO 相的形成,而且还促进了粗非 DRX 和细 DRX 晶粒中晶内层状和薄 14H-LPSO 相的动态沉淀,分别, 在热挤压过程中。其次,增加的块状 18R 体积分数和层状 14H 数密度显着延迟了 DRX。然而,随着变形应变的增加,破碎的 18R 碎片加速了 DRX 粒子激发成核 (PSN) 机制,并且波动的 α-Mg/18R 界面启动了不连续的 DRX 机制。特别是,层状 14H 的变形扭结和溶解激活了连续 DRX 机制。最后,随着热挤压Mg-Y-Zn合金中Y和Zn原子含量的增加,机械强度增加但延展性降低。热挤压镁的高强度94 Y 4 Zn 2合金具有细的 DRX 晶粒尺寸、强的非 DRX 晶粒、主要块状 18R 和层状/薄 14H 相以及变形扭结,而热挤压 Mg 98.5 Y 1 Zn 0.5合金延展性负责大的 DRX 体积分数、变形孪晶的高活性和基底滑移的易移动性。

更新日期:2023-02-25
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