Strengthening of high-entropy alloys via modulation of cryo-pre-straining-induced defects
Strengthening of high-entropy alloys via modulation of cryo-pre-straining-induced defects
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DOI：
10.1016/j.jmst.2022.04.055
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
Daixiu Wei;W. Gong;Liqiang Wang;Bowen Tang;T. Kawasaki;S. Harjo;Hidemi Kato
中科院分区：
文献类型：
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作者：
Daixiu Wei;W. Gong;Liqiang Wang;Bowen Tang;T. Kawasaki;S. Harjo;Hidemi Kato
高熵合金和中熵合金由于其独特的结构和力学性能，引起了人们的广泛研究兴趣。另一方面，具有单一面心立方（FCC）相的HEAs/MEA的强度需要改进。因此，在这项研究中，我们展示了一种策略，通过调整低温预应变诱导的晶体缺陷，通过温度依赖性堆垛层错能量调节塑性机制，增加FCC相HEAs/MEAs的室温强度。通过中子衍射线形分析和电子显微镜观察，阐明了调谐缺陷对拉伸强度的影响。由于低温轧制引起的高位错密度、机械孪晶和层错，等原子CoCrFeNi HEA的室温屈服强度从243 MPa（再结晶态）增加到941.6 MPa（30%低温轧制），同时保持18%的拉伸伸长率。在通过热处理部分恢复后，屈服强度和极限拉伸强度分别略微下降至869和936 MPa。相反，伸长率增加到25.6%。位错密度和分布的位错被发现有助于森林位错引起的强化，这值得进一步研究。本研究探讨借由调整预应变所诱发之晶体缺陷来发展单相高效能高性能高能气体放大器之可能性。
Owing to their attractive structure and mechanical properties, high-entropy alloys (HEAs) and medium-entropy alloys (MEAs) have attracted considerable research interest. The strength of HEAs/MEAs with a single face-centered cubic (FCC) phase, on the other hand, requires improvement. Therefore, in this study, we demonstrate a strategy for increasing the room-temperature strength of FCC-phase HEAs/MEAs by tuning cryo-pre-straining-induced crystal defects via the temperature-dependent stacking fault energy-regulated plasticity mechanism. Through neutron diffraction line profile analysis and electron microscope observation, the effect of the tuned defects on the tensile strength was clarified. Due to the cryo-rolling-induced high dislocation density, mechanical twins, and stacking faults, the room-temperature yield strength of an equiatomic CoCrFeNi HEA was increased by ∼290%, from 243 MPa (as-recrystallized) to 941.6 MPa (30% cryo-rolled), while maintaining a tensile elongation of 18%. After partial recovery via heat treatment, the yield strength and ultimate tensile strength decreased slightly to 869 and 936 MPa, respectively. Conversely, the elongation increased to 25.6%. The dislocation density and distribution of the dislocations were found to contribute to the strengthening caused by forest dislocations, which warrants further investigation. This study discussed the possibility of developing single-phase high-performance HEAs by tuning pre-straining-induced crystal defects.