Micro-characteristic of Strengthened Al 0.1 CoCrFeNi Alloy from Aluminum-Addition Friction Stir Processing
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JMEPEG https://doi.org/10.1007/s11665-020-04931-6
Micro-characteristic of Strengthened Al0.1CoCrFeNi Alloy from Aluminum-Addition Friction Stir Processing Hui-jie Zhang, Zi-jie Ji, Hui-jie Liu, Hao Zhang, Shao-hua Luo, Rui-bin Mei, and Ying-ling Wang (Submitted May 3, 2020; in revised form June 10, 2020) 1060 Al and Al0.1CoCrFeNi are friction stir lap welded in this study in order to improve the microstructure and mechanical property of the high-entropy alloy by adding Al element into the alloy through friction stir processing. The results indicate that a crescent-shaped aluminum-addition zone featured by limited upward material flow is formed in the high-entropy alloy. The aluminum-addition friction stir processing leads to the formation of fine and homogeneously distributed microstructures and the occurrence of body-centered cubic phases in the high-entropy alloy. Owing to the synthetical strengthening effects caused by friction stir modification and Al content increase, the hardness of the Al0.1CoCrFeNi alloy is increased significantly from 100 Hv to an average value over 400 Hv and a maximum value of 600 Hv. The present study is able to provide an effective approach for the preparation and strengthening of high-entropy alloys. Keywords
aluminum addition, high-entropy alloy
friction
stir
processing,
1. Introduction High-entropy alloys (HEAs) are potential metallic materials including five or more elements in equal or near-equiatomic compositions. The outstanding properties qualify the HEAs as potential structural and functional materials in the field of aviation, biomedicine, atomic power and energy. Among the HEAs, AlxCoCrFeNi alloy has achieved extensive attention due to its excellent specific strength, low-temperature mechanical properties and radiation resistance (Ref 1, 2). Concerning the AlxCoCrFeNi alloy, Al content can change the single-phase solid solution structure and has an impact on alloy properties. A large number of studies have shown that with the increase in Al content, the phase structure of AlxCoCrFeNi evolves from facecentered cubic (FCC) phase to body-centered cubic (BCC) phase, leading to a hardness increase in the alloy (Ref 3-5). The BCC-structured HEAs usually have high strengths and limited plasticity, while the FCC-structured HEAs have low yield strength and high plasticity. Therefore, the mixture of BCC + FCC is expected to possess balanced mechanical properties (Ref 1). Preparing the AlxCoCrFeNi with high Al content by traditional casting or powder metallurgy methods tends to induce the inhomogeneous microstructure, shrinkage porosity or element segregation, which has become the key factor to restrict the performance of AlxCoCrFeNi alloy (Ref 6-8). In Hui-jie Zhang, Zi-jie Ji, Hao Zhang, Shao-hua Luo, Rui-bin Mei, and Ying-ling Wang, School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004, PeopleÕs Republic of China; and Hui-jie Liu, State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, PeopleÕs Repub
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