Abstract
Nanocrystalline materials possess high defect-sink density, but often experience radiation-enhanced grain coarsening. With the intrinsic sluggish diffusion and radiation tolerance, high entropy alloys (HEA) may have superior radiation tolerance in their nanocrystalline form. In this study, CoCrFeNiMn HEA samples were processed via high-pressure torsion (HPT) under 6 GPa at room temperature for 1 (1T) and 8 (8T) turns to form nanograins with unsaturated and saturated plastic deformation, respectively. After 3.4MeV Ni ion irradiation at 500 °C, grain growth was observed in both HPT-processed samples. The microstructural evolution is dependent on pre-irradiation HPT processing, with the 8T sample showing stronger radiation tolerance against dislocation development and hardness changes, observed through transmission electron microscopy and nanoindentation, respectively. This radiation resistance is attributed to a unique nanodomain microstructure formed within the radiation-coarsened grains of the 8T sample. Microstructural and microchemical analysis suggested both HPT process and the alloy chemistry played roles in the nanodomain formation.
Original language | English |
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Article number | 115628 |
Journal | Scripta Materialia |
Volume | 235 |
DOIs | |
State | Published - Oct 2023 |
Externally published | Yes |
Funding
This study was supported in part by the National Science Foundation of the United States under grant no. DMR-1810343 . The Thermo Fisher Scientific (FEI) SciosTM 2 DualBeam ultra-high-resolution analytical FIB-SEM at Alfred University system is supported by the National Science Foundation under grant no. 2018306 . Spencer Doran acknowledged the Department of Energy, Office of Nuclear Energy for the Integrated University Program Scholarship and the University Nuclear Leadership Program Scholarship, and the Society of Mining, Metallurgy, and Exploration for the WAAIME Scholarship. Tianyi Chen acknowledged the support of the start-up funds by Oregon State University.
Keywords
- Coarsening
- High entropy alloys
- Nanocrystalline materials
- Nanostructure
- Severe plastic deformation