2019 Fiscal Year Research-status Report
Stabilizing gamma prime phase using Suzuki segregation to enhance the creep resistance of Co-Ni-based superalloy
| Project/Area Number |
19K23566
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| Research Institution | Tohoku University |
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Principal Investigator |
卞 華康 東北大学, 金属材料研究所, 助教 (30796230)
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| Project Period (FY) |
2019-08-30 – 2021-03-31
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| Keywords | Co-Ni-based superalloy / gamma prime / Suzuki segregation / creep resistance |
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| Outline of Annual Research Achievements |
The microstructure of the designed Co-Ni-based superalloy which is strengthened by gamma prime phase and Suzuki segregation was observed using in-situ TEM at high temperature of 700 centigrade. The in-situ TEM observation is a powerful method to figure out how the stacking fault form and broaden due to the segregation of solute atoms (Suzuki segregation) via recording the movement of dislocation.
Beside that several button shaped alloys with the addition of Re and/or B were prepared using arc melting method. The hot forging was carried out at 1200 centigrade to obtain the homogeneous microstructure. With addition of Re and/or B, precipitate can form along grain boundary to enhance the grain boundary strength. Thus the creep resistance is expected to be enhanced.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Several button-shaped alloys have been prepared using arc melting method with addition of 3% Re while 0-0.1 B. The hot forging has been carried out at 1200 centigrade to obtain the homogeneous microstructure. The microstructure has been observed after hot forging. Beside that, in-situ TEM observation has been performed sevaral times at 700 centigrade to try to observe the motion of dislocation.
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| Strategy for Future Research Activity |
1. The in-situ TEM observation will be conducted using STEM in future because the normal TEM has low magnification and the oxidation occurred during heating.
2. The cold rolling and aging at various temperatures will be performed in next step.
3. The microstructure in particular along the grain boundary will be observed to check the precipitate along grain boundary.
4.The tensile tests and the stress relaxation tests at high temperatures will be carried out to examine the creep resistance.
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