1990 Fiscal Year Final Research Report Summary
Interstitial Helium Diffusion in Metals
| Project/Area Number |
01460214
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | Hiroshima University |
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Principal Investigator |
HASHIMOTO Eiji Hiroshima Univ., Faculty of Science, Associate Professor, 理学部, 助教授 (50033907)
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| Co-Investigator(Kenkyū-buntansha) |
KOSUGI Toshio Hiroshima Univ., Faculty of Science. Research Associate, 理学部, 助手 (10153545)
UEDA Yoshitake Hiroshima Univ., Faculty of Science, Research Associate, 理学部, 助手 (80106799)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Helium in Metals / Diffusion in Solids / Thermal- Desorption Method / Interstitial Atlm / Ion Irradiation |
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| Research Abstract |
In order to get information about the diffusion of interstitial helium in metals. Measurements have been made on the thermal desorption of helium from high purity aluminum irradiated with 19 keV He ions. The irradiation was performed at room temperature up to 1 x 10^<15> - 5 x 10^<16> He^+cm^<-2>.
Remarkable features of the results are as follows. (1) Almost all helium atoms implanted are released released during heating up to the melting point or more. (2) A rapid helium evolution occurs just below the melting point, irrespective of irradiation dose. (3) For irradiation more than 5 x 10^<15> He^+cm^<-2>, another evolution rate peak appears ; the peak area is increased markedly with increasing irradiation dose, while the peak position is shifted to the lowler temperature side. In particular, the result (3) suggests that the evolution peak appearing in the lower temperature region may be due to diffusion and evolution of helium emitted spontaneously from small cavities containing a large number of helium atoms. According to the above, the activation energy for the helium evolution in the lower temperature region (100-200 ^ﾟC) was estimated from the desorption rates before and after the abrupt temperature chane during stepwise heating. The value obtained is about 0.3 eV. This value is very close to thouse (0.2-0.3 eV) calculated for interstitial helium diffusion in aluminum.
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