| Project/Area Number |
19K23566
|
|---|
| Research Category |
Grant-in-Aid for Research Activity Start-up
|
| Allocation Type | Multi-year Fund |
|---|
| Review Section |
0401:Materials engineering, chemical engineering, and related fields
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
Huakang Bian 東北大学, 金属材料研究所, 助教 (30796230)
|
|---|
| Project Period (FY) |
2019-08-30 – 2021-03-31
|
| Project Status |
Completed (Fiscal Year 2020)
|
| Budget Amount *help |
¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
|
|---|
| Keywords | Superalloy / Ni-Co-based alloy / Suzuki segregation / gamma prime / Co-Ni-based Superalloy / Creep / Re addtition / Co-Ni-based superalloy / creep resistance / Creep resistance / Stabilizing |
|---|
| Outline of Research at the Start |
The service life of Ni-based superalloy will be reduced by the coarsening or rafting of the γ' phase particles at high temperature,which has been successfully slowed down by the applicant using Suzuki segregation. Thus, the service life is expected to be prolonged by introducing Suzuki segregation.
|
| Outline of Final Research Achievements |
CoーNi-based superalloy was designed via Suzuki segregation strengthening which showed excellent mechanical properties at RT and high temperature. However, it shows low ductility and poor creep resistance at high temperature. The reason was attributed to the weakness of grain boundary which gives rise to intercrystalline fracture. Thus, it is necessary to enhance the strength of grain boundary. Thus, in the present research proposal, 1, 2, and 3 wt% Re was added into the developed CoーNi-based superalloy to study how Re influence the grain boundary. Beside that little B is also will be introduced to further strengthening the grain boundary. After addition of 1, 2, and 3 wt% Re, the tensile elongation increased to 14%, 23%, and 20% at RT respectively while 8%, 15%, and 18% at 700 ℃. the brittleness was obviously improved due to the enhancement of grain boundary. And the mechanism of how Suzuki segregation slowed down the coarsening of γ' phase was figured out via STEM observation.
|
| Academic Significance and Societal Importance of the Research Achievements |
鈴木効果に関する研究は長い時間で趣味になっている。特に積層欠陥エネルギー低い生体材料CCM合金における、鈴木偏析が発生しやすい。申請者ら、CCMをベースにして、γ'強化を導入、Co-Ni基超合金を開発した。さらに、鈴木偏析は高温でγ'相粗大化を抑える効果を初発見した。本提案はSTEM観察を行った、その粗大化抑えるメカニズムを解明した。さらに、このCo-Ni基超合金は延性が低い、耐クリープ性が悪い。耐クリープ性アープするため、Reを添加した。Reを添加すると、延性がよく改善された。特に、２wt% Reの添加は、最適化するとこを確認された。この研究結果により、未来もといい合金の開発を目指している。
|
