Lamellar aspect-ratio and thickness-dependent strength-ductility synergy in pure nickel during in-situ micro-tensile loading
Lamellar aspect-ratio and thickness-dependent strength-ductility synergy in pure nickel during in-situ micro-tensile loading
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DOI：
10.1016/j.jmst.2023.01.037
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
Z. Wang;Yun-Fei Jia;Kai-Shang Li;Yong Zhang;Jiazi Cai;Xian‐Cheng Zhang;H. Hirakata;Shangdong Tu-Shangdo
中科院分区：
文献类型：
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作者：
Z. Wang;Yun-Fei Jia;Kai-Shang Li;Yong Zhang;Jiazi Cai;Xian‐Cheng Zhang;H. Hirakata;Shangdong Tu-Shangdo
为了克服传统金属材料在强度和塑性之间的权衡，采用超声深轧技术对高层错能纯镍进行热处理，制备出了梯度层状组织。梯度片层镍依次分为三个区域。在不同的区域进行了原位微拉伸试验，以揭示相应的微观力学行为。采用微观表征技术，探讨了显微组织参数和缺陷对力学性能的影响。研究表明，当加载方向平行于片层晶界的长边时，具有小片层厚度和大长宽比的微拉伸试件具有良好的强度和塑性。这一发现有助于设计具有优异综合性能的金属材料微观组织。一方面，强度高的原因是根据Hall-Petch效应，强度随层片厚度的减小而增加。此外，初始位错密度也参与了强化机制。另一方面，变形机制包括位错滑移、晶界旋转和晶界对位错的影响，共同促成了良好的塑性。
In order to overcome the trade-off between strength and ductility in traditional metallic materials, the gradient lamellar structure was fabricated through an ultrasound-aided deep rolling technique in pure Ni with high stacking fault energy after heat treatment. The gradient lamellar Ni was successively divided into three regions. In-situ micro-tensile tests were performed in different regions to reveal the corresponding microscopic mechanical behaviors. Microscopic characterization techniques were adopted to explore the effects of microstructural parameters and defects on mechanical properties. This work demonstrates that the micro-tensile sample with small lamellar thickness and large aspect ratio possesses excellent strength and ductility when the loading direction is parallel to the long side of lamellar grain boundaries. The finding is helpful to the design of metallic material microstructure with superior comprehensive properties. On one hand, the reason for high strength is that the strength increases with the decrease of lamellar thickness according to the Hall-Petch effect. Besides, initial dislocation density also participates in the strengthening mechanism. On the other hand, the deformation mechanisms include dislocation slip, grain rotation, and the effects of grain boundaries on dislocations, jointly contributing to good ductility.