Microstructure and mechanical properties of Al-7075 alloy processed by equal channel angular pressing combined with aging treatment |
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| Affiliation: | 1. Department of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran 1684613114, Iran;2. Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, South Korea;1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, PR China;2. Department of Chemical Engineering and Materials Science, University of California, Davis, United States;1. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Xueyuan Road 30, Haidian District, Beijing 100083, China;2. School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road 30, Haidian District, Beijing 100083, China;1. Department of Mechanical Engineering, SVEC, Tirupati 517102, India;2. Department of Mechanical Engineering, SRKRCE, Bhimavaram 534201, India;3. Department of Mechanical Engineering, Andhra University, Visakhapatnam 530003, India;4. Department of Mechanical Engineering, SVEC-517102 Tirupati, India;1. School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. 11155-4563, Tehran Iran;2. Department of Materials Engineering, University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran;3. Department of Materials Science and Engineering, School of Engineering, Shiraz University, P.O. Box 71348-51154, Shiraz, Iran |
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| Abstract: | In order to examine the combined effect of plastic deformation and aging process, the Al 7075 alloy was subjected to equal channel angular pressing (ECAP) deformation by route BC in various ECAP and aging conditions: pre-ECAP aging, post-ECAP aging and dynamic aging during ECAP at 393 K and 423 K. Followed by ECAP and aging treatment, Vickers microhardness and tensile test were performed and microstructural observations were undertaken using transmission electron microscopy (TEM) and X-ray diffractometer (XRD). TEM investigation showed that ultrafine-grained (UFG) materials with grain size less than 500 nm could be obtained after three or four passes of ECAP. Precipitates characterization revealed that maximum mechanical properties are achieved when the microstructure mainly consists of fine dispersion of small η′ precipitates and minor quantities of GP zones. Dynamic aged specimens at 393 K and 423 K represented maximum and minimum mechanical properties, respectively, due to formation of fine η′ precipitates plus GP zones and η′ plus η precipitates, respectively. Dynamic aging during ECAP at 393 K appeared preferable to other procedures for attaining maximum mechanical properties as well as saving time and energy. |
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| Keywords: | Equal channel angular pressing Microstructure Age hardening treatment Strength Microhardness |
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