1993 Fiscal Year Final Research Report Summary
Interaction of helium with irradiation defects in metals
| Project/Area Number |
03402053
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Nuclear engineering
|
|---|
| Research Institution | Institute for materials research.Tohoku University |
|---|
Principal Investigator |
MATSUI Hideki Institute for Materials Rcascarch, Professor, 金属材料研究所, 教授 (50005980)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YANO Shinzo Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (60005915)
MINONISHI Yasuhide Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (70005958)
KIMURA Akihiko Institute for Materials Research, Associate Professor, 金属材料研究所, 助教授 (90195355)
|
|---|
| Project Period (FY) |
1991 – 1993
|
| Keywords | Fusion reactor materials / helium effects / thermal helium desorption / vanadium alloys / ferritc steels / irradiation defects |
|---|
| Research Abstract |
A coherent picture on the interaction of helium with irradiation defects has been established as a result of the present project : When displacement damage is significantly less than the amount of helium introduced, the fraction of interstitial helium is large and they diffuse very rapidly. Accumulation of helium to grain boundaries is high in this case leading to intergranular embrittlement. This situation is most pronounced for tritium trick technique and cyclotron implantation follows. When speciments doped with helium using tritium trick technique are irradiated with neutrons, helium is trapped mainly by irradiation-induced vacancies and helium transport to grain boundaries is suppressed and embrittlement is mitigated. Under DHCE condition where displacement damage is introduced concurrently with helium generation, helium generated is immediately trapped by vacancies and helium embrittlement has been found significantly reduced. Since this situation is quite similar to fusion environment, this finding leads to a very important conclusion that helium embrittlement may not be so significant as has been anticipated.
A clear correlation of the interaction between solute atoms and helium with solute atomic size factor became evident. Namely, strongly undersized solutes, e.g.iron and chromium, traps helium strongly and suppress their diffusion. This finding was obtained from TEM and THDS experiments on speciments helium-injected with an energy under displacement thershold energy. This kind of property of undersized solutes may be effective in suppressing helium embrittlement at high temperatures.
|
