A high-strength low-rare-earth-alloyed magnesium alloy via traditional hot-extrusion
A high-strength low-rare-earth-alloyed magnesium alloy via traditional hot-extrusion
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DOI：
10.1016/j.jallcom.2019.151967
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发表时间：
2019-11-25
影响因子：
6.2
通讯作者：
Meng, Jian
中科院分区：
文献类型：
--
作者：
Zhang, Dongdong;Yang, Qiang;Meng, Jian
采用热挤压+人工时效的铸锭冶金工艺制备了低稀土含量的高强度Mg-3.5Sm-2 Yb-0.6Zn-0.4Zr合金。峰时效态的屈服强度为449 MPa，高于大部分挤压态高稀土Mg-Gd基合金，甚至与T8处理的2024铝合金相当。所研究的合金表现出典型的双峰微观结构，包括动态再结晶（DRXed）晶粒与随机纹理和粗的未再结晶区域与强的基底纤维织构。此外，破碎的Mg 5 RE和Mg 41 RE 5相分布在挤出纵梁处。在DXRed区动态析出大量细小的Mg3 RE颗粒，通过晶界钉扎有效地抑制了DXRed晶粒的长大。在unDXRed区域内，观察到均匀致密的Mg3 RE和Mg 12 RE纳米析出物。在非DXRed区也有大量的基底< a >位错和少量的非基底< c + a >位错。随后的人工时效通过引入基底沉淀物显著提高了合金的强度，但略微降低了延展性。最后，研究表明，该复合材料的屈服强度是由强的基体纤维织构、双峰显微结构和大量沉淀颗粒共同作用的结果。(C)2019 Elsevier B. V.版权所有。
A high-strength low-rare-earth-alloyed Mg-3.5Sm-2Yb-0.6Zn-0.4Zr alloy was processed by an ingot metallurgy process with hot-extrusion followed by artificial aging. The peak-aged sample exhibited a higher yield strength of 449 MPa than most of extruded Mg-Gd based alloy containing high RE content, and even is comparable to that of the T8-treated 2024 Al alloy. The studied alloy exhibited a typical bimodal microstructure, consisting of dynamically recrystallized (DRXed) grains with random textures and coarse unrecrystallized regions with strong basal fiber texture. In addition, the fragmented Mg5RE and Mg41RE5 phases distributed at extrusion stringers. Abundant of fine Mg3RE particles precipitated dynamically in DXRed regions, which restrains DRXed grains growth effectively by grain boundary pinning. Within the unDXRed regions, uniformly dense Mg3RE and Mg12RE nano-precipitates were observed. Also there were many basal < a > dislocations and a few non-basal < c + a > dislocations in unDXRed regions. Subsequent artificial ageing significantly enhanced the alloy's strength by introducing basal precipitates, although decreased the ductility slightly. Finally, the ultrahigh yield strength was revealed to be attributed to the combined effects of a strong basal fiber texture, a bimodal microstructure, and numerous precipitated particles. (C) 2019 Elsevier B.V. All rights reserved.