| Project/Area Number |
22K20478
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0401:Materials engineering, chemical engineering, and related fields
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| Research Institution | Yokohama National University |
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Principal Investigator |
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| Project Period (FY) |
2022-08-31 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Fiscal Year 2023: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2022: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | High entropy alloy / Microstructure / Mechanical Properties / Texture / Neutron scattering / Recrystallization / High entropy alloys / Nutron diffraction / Microstructure control / Mechanical properties / Neutron diffraction / Heat treatment / Plastic deformation / high entropy alloys / Dislocation density |
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| Outline of Research at the Start |
To enhance strength-ductility trade-off, the dislocation characteristics should be studied with microstructure design. In this study, microstructure of C-doped FeNiCoCr HEA i.e., grain size and carbide content is tuned for optimizing dislocation activities in order to balance strength-ductility.
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| Outline of Final Research Achievements |
The strength-ductility trade-off in CoCrFeNi alloy has been dealt with 1at% carbon addition and microstructure fabrication during annealing. The carbon addition leads to being capable of carbon precipitation strengthening combined with increased grain boundary strengthening and solid solution strengthening. The precipitate and microstructure characteristics were interplayed with different annealing conditions. More uniform grain sizes and coarser particles in the samples annealed at 1000°C for 60 min (391 MPa of yield strength) compensated for a decrease in yield strength, in a comparison with the sample annealed at 900°C for 60 min (514 MPa of yield strength), where the inhomogeneous grain sizes and fine particle arrays were formed. However, the elongations of these two samples are similar between 35% - 40%. Their strengths were correlated to dislocation accumulation during plastic deformation.
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| Academic Significance and Societal Importance of the Research Achievements |
In-situ neutron diffraction experiment was carried out to study microstructure evolution of CoCrFeNi + 1at%C alloy during annealing and tensile deformation. High strength and ductility are resulted by fine grain sizes, nanosized precipitates and deformation mechanism (shear-bands and twinning).
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