Microstructure and mechanical properties of CoCrFeMnNi high entropy alloy with ultrasonic nanocrystal surface modification process
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2020年第22期
论文作者：Timothy Alexander Listyawan Hyunjong Lee Nokeun Park Unhae Lee
摘 要：In this study, mechanical properties improvement of equiatomic CoCrFeMnNi treated with an ultrasonic nanocrystal surface modification（UNSM） was studied. The applied UNSM treatment with static loads of 10 N, 20 N, and 60 N provided a severe plastic deformation, which produced a gradient structure. The nearsurface area exhibited a high number of dislocation densities and deformation twin interaction, leading to a surface strengthening and hardness improvement of up to 112% than the deformation-free interior region. Increment of dislocation densities and deformation twin formation on the surface also enhanced the yield and ultimate tensile strength of the UNSM-treated specimens. Furthermore, the combination of hard nanocrystallites layer on the surface and ductile coarse grain in the specimen interior as a result of the UNSM treatment successfully maintained the strength–ductility balance of the CoCrFeMnNi.
Timothy Alexander Listyawan1，Hyunjong Lee2，Nokeun Park1,3，Unhae Lee4
1. School of Materials Science and Engineering, Yeungnam University2. Advanced Process and Materials R&D Group, Korea Institute of Industrial Technology3. Institute of Materials Technology, Yeungnam University4. POSCO Technical Research Laboratories
摘 要：In this study, mechanical properties improvement of equiatomic CoCrFeMnNi treated with an ultrasonic nanocrystal surface modification（UNSM） was studied. The applied UNSM treatment with static loads of 10 N, 20 N, and 60 N provided a severe plastic deformation, which produced a gradient structure. The nearsurface area exhibited a high number of dislocation densities and deformation twin interaction, leading to a surface strengthening and hardness improvement of up to 112% than the deformation-free interior region. Increment of dislocation densities and deformation twin formation on the surface also enhanced the yield and ultimate tensile strength of the UNSM-treated specimens. Furthermore, the combination of hard nanocrystallites layer on the surface and ductile coarse grain in the specimen interior as a result of the UNSM treatment successfully maintained the strength–ductility balance of the CoCrFeMnNi.
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