Cryogenic strength improvement by utilizing room-temperature deformation twinning in a partially recrystallized VCrMnFeCoNi high-entropy alloy.
Cryogenic strength improvement by utilizing room-temperature deformation twinning in a partially recrystallized VCrMnFeCoNi high-entropy alloy.
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DOI：
10.1038/ncomms15719
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发表时间：
2017-06-12
影响因子：
16.6
通讯作者：
Lee S
中科院分区：
文献类型：
--
作者：
Jo YH;Jung S;Choi WM;Sohn SS;Kim HS;Lee BJ;Kim NJ;Lee S
CrMnFeCoNi合金优异的低温拉伸性能一般是由形变孪晶引起的，而形变孪晶在室温下难以实现，因为孪晶应力不足。在这里，我们诱导在室温下的孪生，以提高CrMnFeCoNi合金的低温拉伸性能。考虑到晶粒尺寸对孪晶临界应力的影响，在不进行热轧晶粒细化的情况下，通过冷轧容易在粗大的组织中形成孪晶。这些孪晶保留部分再结晶，并发挥了重要作用，提高强度，使屈服强度接近1 GPa。在再结晶区和非再结晶区的额外孪晶导致了高达46%的持久延伸率和1.3GPa的抗拉强度。我们的研究结果表明，非再结晶晶粒，这通常是避免在传统的合金，因为它们对延展性的有害影响，可以是有用的，在实现高强度高熵合金。CrMnFeCoNi高熵合金在低温下由于形变孪晶而具有高的断裂韧性，但在室温下该合金中的孪晶不活跃。在这里，作者优化了成分和热机械处理，以引入非再结晶晶粒，产生高屈服强度，同时保持良好的延展性。
The excellent cryogenic tensile properties of the CrMnFeCoNi alloy are generally caused by deformation twinning, which is difficult to achieve at room temperature because of insufficient stress for twinning. Here, we induced twinning at room temperature to improve the cryogenic tensile properties of the CrMnFeCoNi alloy. Considering grain size effects on the critical stress for twinning, twins were readily formed in the coarse microstructure by cold rolling without grain refinement by hot rolling. These twins were retained by partial recrystallization and played an important role in improving strength, allowing yield strengths approaching 1 GPa. The persistent elongation up to 46% as well as the tensile strength of 1.3 GPa are attributed to additional twinning in both recrystallized and non-recrystallization regions. Our results demonstrate that non-recrystallized grains, which are generally avoided in conventional alloys because of their deleterious effect on ductility, can be useful in achieving high-strength high-entropy alloys. CrMnFeCoNi high entropy alloys have high fracture toughness at cryogenic temperatures due to deformation twinning but twinning is not active in this alloy at room temperature. Here authors optimize composition and thermomechanical treatments to introduce non-recrystallized grains, producing high yield strength while maintaining good ductility.