Microstructure and mechanical properties of CoCrFeMnNi high entropy alloy with ultrasonic nanocrystal surface modification process

• 作者: Timothy Alexander Listyawan Hyunjong Lee Nokeun Park Unhae Lee
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2020,（22）
• 页码范围: 123-130
• 页数: 8页
• 语种: 英文

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 near-surface 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.