Probing deformation mechanisms of gradient nanostructured CrCoNi medium entropy alloy
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2020年第22期
论文作者：Jia Li Li Li Chao Jiang Qihong Fang Feng Liu Yong Liu Peter K.Liaw
摘 要：The gradient nanostructured medium entropy alloys（MEAs） exhibit a good yielding strength and great plasticity. Here, the mechanical properties, microstructure, and strain gradient in the gradient nanostructured MEA CrCoNi are studied by atomic simulations. The strong gradient stress and strain always occur in the deformed gradient nanograined MEA CrCoNi. The origin of improving strength is attributed to the formation of the 9 R phase, deformation twinning, as well as the fcc to hcp phase transformation, which prevent strain localization. A microstructure-based predictive model reveals that the lattice distortion dependent solid-solution strengthening and grain-boundary strengthening dominate the yield strength,and the dislocation strengthening governs the strain hardening. The present result provides a fundamental understanding of the gradient nanograined structure and plastic deformation in the gradient nanograined MEA, which gives insights for the design of MEAs with higher strengths.
Jia Li1，Li Li1，Chao Jiang1，Qihong Fang1，Feng Liu2，Yong Liu2，Peter K.Liaw3
1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University2. State Key Laboratory of Powder Metallurgy, Central South University3. Department of Materials Science and Engineering, The University of Tennessee
摘 要：The gradient nanostructured medium entropy alloys（MEAs） exhibit a good yielding strength and great plasticity. Here, the mechanical properties, microstructure, and strain gradient in the gradient nanostructured MEA CrCoNi are studied by atomic simulations. The strong gradient stress and strain always occur in the deformed gradient nanograined MEA CrCoNi. The origin of improving strength is attributed to the formation of the 9 R phase, deformation twinning, as well as the fcc to hcp phase transformation, which prevent strain localization. A microstructure-based predictive model reveals that the lattice distortion dependent solid-solution strengthening and grain-boundary strengthening dominate the yield strength,and the dislocation strengthening governs the strain hardening. The present result provides a fundamental understanding of the gradient nanograined structure and plastic deformation in the gradient nanograined MEA, which gives insights for the design of MEAs with higher strengths.
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