Precipitation hardening of an Mg-5Zn-2Gd-0.4Zr (wt. %) alloy
Precipitation hardening of an Mg-5Zn-2Gd-0.4Zr (wt. %) alloy
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DOI：
10.1016/j.actamat.2016.01.053
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发表时间：
2016-04-15
期刊：
影响因子：
9.4
通讯作者：
Schumacher, P.
中科院分区：
文献类型：
--
作者：
Li, J. H.;Barrirero, J.;Schumacher, P.
Mg - 5 -锌- 2 - gd - 0.4 -锆合金(wt %)显示了一个重要的时效硬化反应硬度增加从62高压72高压老龄化在200摄氏度80 h。透射电子显微镜和原子探针断层特征表明,沉淀与飞机不同的形态和习惯形成合金,包括三角形ZnZr阶段,长方形Zn2Zr阶段,[0001](Mg)棒(β(1)”)MgZn2冲洗阶段,(0001)(Mg)板(β(2)”)MgZn2冲洗阶段,和连贯的GP区。此外，首次观察到Gd向富zn析出相(β（1)′和β(2)′）的明显分块，这被认为是提高富zn析出相热稳定性和增强合金析出硬化的原因。同时还观察到Gd（类似于2 at%）的壳层和Zn2Zr相的核壳结构，这可能会阻碍Zn2Zr相的粗化。时效15 h后，Zn2Zr颗粒的平均尺寸没有进一步变化。更好地了解Gd在富zn析出相中的分配和核壳结构的形成对控制析出组织和开发高性能镁合金具有重要意义。(C) 2016材料学报Elsevier Ltd.出版。版权所有。
Mg-5Zn-2Gd-0.4Zr alloy (wt. %) shows a significant age hardening response with a hardness increment from 62 HV to 72 HV by ageing at 200 degrees C for up to 80 h. Transmission electron microscopy and atom probe tomography characterizations reveal that precipitates with different morphologies and habit planes form in the alloy, including triangular-shaped ZnZr phase, rectangular-shaped Zn2Zr phase, [0001](Mg) rods (beta(1)') MgZn2 Laves phase, (0001)(Mg) plate (beta(2)') MgZn2 Laves phase, and coherent GP zones. Furthermore, a significant partitioning of Gd into Zn-rich precipitates (beta(1)' and beta(2)') was, for the first time, observed, which is considered to be responsible for improving the thermal stability of Zn-rich precipitates and enhancing the precipitation hardening of the alloy. A core-shell structure with the shell of Gd (similar to 2 at%) and the core of Zn2Zr phase was also observed, which is proposed to hinder the coarsening of Zn2Zr phase. No further change in average size of the Zn2Zr particles was observed after ageing over 15 h. Better understanding the partitioning of Gd into the Zn-rich precipitates and the formation of the core-shell structures are essential to control the precipitation microstructure and develop high performance Mg alloys. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.