Effects of pre-annealing on microstructure and mechanical properties of as-extruded Mg-Gd-Y-Zn-Zr alloy
Effects of pre-annealing on microstructure and mechanical properties of as-extruded Mg-Gd-Y-Zn-Zr alloy
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DOI：
10.1016/j.jallcom.2017.09.214
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发表时间：
2017-12-30
影响因子：
6.2
通讯作者：
Kamado, Shigeharu
中科院分区：
文献类型：
--
作者：
Yu, Zijian;Xu, Chao;Kamado, Shigeharu
通过预退火和热挤压工艺，成功地研制出了具有良好强塑性平衡的挤压态Mg-11.5Gd-4.5Y-1.5Zn-0.4Zr(wt%)合金。研究了预退火对合金组织和力学性能的影响。结果表明，在热挤压过程中，经预退火处理生成的镁稀土(RE：RE)颗粒在热挤压过程中发生裂解，生成的镁稀土碎片不仅促进了颗粒模拟形核(PSN)的再结晶，而且促进了连续动态再结晶(C-DRX)。经热挤压后，合金呈现双峰组织，细小的DRXed晶粒具有相对无规则的取向，粗大的未DRXed晶粒具有强烈的基面织构。随着预退火时间的延长，镁稀土颗粒数量增加，DRX含量增加，从而降低了强度，但提高了塑性。预退火1h后，合金的强塑性达到最佳平衡，拉伸屈服强度(TYS)为377+/-1.2 Mpa，断裂伸长率(EL)为10.8+/-2.0%。进一步的预退火会由于过量的Mg5RE颗粒而使塑性降低。合金的强化是由双峰组织、镁稀土和长周期堆积有序相(LPSO)、溶质偏析SFS和织构所致。(C)2017年，由爱思唯尔出版。
An as-extruded Mg-11.5Gd-4.5Y-1.5Zn-0.4Zr (wt %) alloy with an excellent strength-ductility balance has been successfully developed by pre-annealing and hot extrusion. The effects of pre-annealing on microstructure and mechanical properties have been studied. Results show that the Mg5RE (RE: rare earth) particles, which are generated by pre-annealing treatments, are cracked during hot extrusion, and resulting Mg5RE fragments not only enhance the recrystallization of particle simulated nucleation (PSN), but also improve the continuous dynamic recrystallization (C-DRX) by promoting the grain subdivision. After hot extrusion, the studied alloy exhibits a bimodal microstructure consisting of fine DRXed grains with relatively random orientations and coarse un-DRXed grains with strong basal texture. Increasing the pre-annealing duration raises both the quantity of Mg5RE particles and the fraction of DRX, thereby decreasing the strength but increasing the ductility. With pre-annealing for 1 h the studied alloy achieves the best strength-ductility balance with tensile yield strength (TYS) of 377 +/- 1.2 MPa and elongation to failure (EL) of 10.8 +/- 2.0%. Further pre-annealing degrades the ductility due to the excessive Mg5RE particles. The alloy strengthening is attributed to the bimodal microstructure, Mg5RE and long-period stacking ordered (LPSO) phases, solute segregated SFs, and texture. (C) 2017 Published by Elsevier B.V.