Developing a low-alloyed fine-grained Mg alloy with high strength-ductility based on dislocation evolution and grain boundary segregation
Developing a low-alloyed fine-grained Mg alloy with high strength-ductility based on dislocation evolution and grain boundary segregation
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基于位错演化和晶界偏析开发高强塑性低合金细晶镁合金
DOI：
10.1016/j.scriptamat.2021.114414
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发表时间：
2021-11-16
影响因子：
6
通讯作者：
Wu, Ruizhi
中科院分区：
文献类型：
--
作者：
Zhang, Zhi;Zhang, Jinghuai;Wu, Ruizhi
采用低温低速挤压工艺制备了一种新型低合金Mg-2Sm-0.8Mn-0.6Ca-0.5Zn（wt.%）合金。挤压态合金具有超高的屈服强度（YS，453 MPa），但延伸率较差（3.2%），这主要是由于形成了含有高密度残余位错和Mn纳米颗粒的细晶结构。更重要的是，经过后续的简单退火后，该合金表现出高强度和高塑性的优异结合，YS为403 MPa，伸长率为15.5%。 Sm/Zn/Ca 晶界 (GB) 共偏析对晶粒生长的有效抑制对于退火合金保持高强度至关重要。适当降低位错密度，特别是不可移动的长S-<c+a>位错向新晶界的演化，是退火合金延展性显着提高的关键因素。因此，我们提出了一种主要基于位错演化和晶界偏析的低合金高强塑镁合金的开发新策略。 (c) 2021 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
A new low-alloyed Mg-2Sm-0.8Mn-0.6Ca-0.5Zn (wt.%) alloy is prepared by low-temperature and low-speed extrusion. The as-extruded alloy has ultra-high yield strength (YS, 453 MPa) but poor elongation (3.2%) mainly due to the formation of a fine-grained structure containing high-density residual dislocations and Mn nanoparticles. More importantly, after subsequent simple annealing, the alloy exhibits an excellent combination of high-strength and high-ductility, with the YS of 403 MPa and elongation of 15.5%. The effective inhibition of grain growth by grain boundary (GB) co-segregation of Sm/Zn/Ca is crucial for the annealed alloy to maintain high strength. Appropriately decreased dislocation density, especially the evolution of immovable long S-< c+a > dislocations towards new GBs, is a key factor for the remarkable increase of ductility for the annealed alloy. Thus, we put forward a new strategy for developing low-alloyed Mg alloy with high strength-ductility mainly based on dislocation evolution and GB segregation. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.