Probing the degenerate pattern growth of {100}<011> orientation in a directionally solidified Al-4.5 wt% Cu alloy |
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| Affiliation: | 1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, 710072, China;2. College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, 266000, China;3. MOE Key Laboratory of Material Physics and Chemistry under Extraordinary, Shaanxi Key Laboratory of Condensed Matter Structure and Properties, Northwestern Polytechnical University, Xi''an, 710129, China;1. School of Materials Science and Engineering, Tianjin University, Tianjin, 300350, China;2. Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569, Stuttgart, Germany;3. Department of Physics, Shantou University, Shantou, 515063, China;1. Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian, 116024, China;2. School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan, 114051, China;3. Department of Orthopedics, The Second Hospital of Dalian Medical University, Dalian, 116024, China;1. Department of Physics, and Shenzhen Institute of Research and Innovation (HKU-SIRI), The University of Hong Kong, Pokfulam Road, Hong Kong, China;2. Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, 215123, China;3. Guangdong Research Center for Interfacial Engineering of Functional Materials, and College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China;1. Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan;2. School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an, 710072, China;3. School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, China |
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| Abstract: | Degenerate pattern is a seemingly disordered morphology but it exhibits the inherently ordered crystal connected with tip-splitting and limited stability which makes it difficult to observe in the metallic system. Here we employ (100)011] orientated planar-front seeds using directional solidification and reveal the fundamental origins of the degenerate pattern growth in an Al-4.5 wt% Cu alloy. We find that the spacing of the tip-splitting (λ) in the degenerate of the alloys followed a power law, λ∝V?0.5, and the frequency (f) of the splitting was related to the growth velocity (V) by ?∝V1.5. The dimensionless growth direction (θ/θ0) increased monotonously and approached 0.6 with faster velocity, attributed to its anisotropy in the interface kinetics. Once growth velocity exceeded a threshold, two types of pattern transitions from degenerate to regular dendrites were proposed. One of them exhibited a random and chaotic mode and the other underwent a rotation in growth direction. |
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| Keywords: | Al-Cu alloy Anisotropy Direction solidification Degenerate pattern |
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