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Journal Articles

Positron annihilation study of hardening in Fe-Cu alloy during low temperature aging

Yamashita, Takako*; Katsuyama, Jinya; Sato, Kaoru*; Mizuno, Masataka*; Araki, Hideki*; Shirai, Yasuharu*

Tetsu To Hagane, 97(11), p.558 - 565, 2011/11

 Times Cited Count:0 Percentile:0.01(Metallurgy & Metallurgical Engineering)

The hardness of Fe-Cu alloys is known to increase by the precipitation of Cu clusters during thermal aging. However, the mechanism of Cu precipitation has not been clarified yet. In this study, the positron lifetime and coincidence Doppler broadening techniques have been used to investigate the recovery behavior of lattice defects such as vacancies, vacancy clusters and dislocations as well as the diffusion behavior of Cu atoms of cold rolled and thermally-aged Fe-Cu alloys. Both vacancies and dislocations caused by cold rolling were reduced through the thermally aging process. Some dislocations remained even after aging at 550$$^{circ}$$C, although the vacancies almost disappeared after aging at 300$$^{circ}$$C. Cu clusters precipitate mainly on the dislocations, where is the sinks of the vacancies, caused by the diffusion of Cu atom and vacancies.

Journal Articles

Interlaboratory comparison of positron annihilation lifetime measurements

Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.

Materials Science Forum, 607, p.248 - 250, 2009/00

So far no standard procedure for the positron annihilation lifetime (PAL) technique has been established. A lack of the standards has led to difficulty in ensuring the equivalency and reliability of data from different laboratories. As a first, we conducted an interlaboratory comparison of PAL measurements for metal, polymer and silica glass with agreed procedures for data recording and analysis. The PAL data recorded at different laboratories were analyzed with a single lifetime component for the metal sample and with three components for the others, respectively. Based on the results of the reported positron and ortho-positronium lifetimes, the possible sources of the uncertainties in the PAL measurements are discussed. To reduce the effect of scattered $$gamma$$ rays, a lead shield was placed between the detectors. The uncertainty was significantly decreased, signifying that placing lead shields between the detectors effectively reduced the false signals due to the scattered $$gamma$$ rays.

Journal Articles

Interlaboratory comparison of positron annihilation lifetime measurements for synthetic fused silica and polycarbonate

Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.

Journal of Applied Physics, 104(2), p.026102_1 - 026102_3, 2008/07

 Times Cited Count:38 Percentile:80.56(Physics, Applied)

Interlaboratory comparison of positron annihilation lifetime measurements using synthetic fused silica and polycarbonate was conducted with the participation of 12 laboratories. By regulating procedures for the measurement and data analysis the uncertainties of the positron lifetimes obtained at different laboratories were significantly reduced in comparison with those reported in the past.

Oral presentation

Pre-strain effect on Cu precipitation in Fe-Cu alloys studied by positron annihilation techniques

Katsuyama, Jinya; Yamano, Yuko*; Yamashita, Takako*; Mizuno, Masataka*; Araki, Hideki*; Shirai, Yasuharu*

no journal, , 

no abstracts in English

Oral presentation

Comparison of positron annihilation measurements of quartz glass and polycarbonate

Kobayashi, Yoshinori*; Ito, Kenji*; Oka, Toshitaka*; Sakaki, Koji*; Shirai, Yasuharu*; Honda, Yoshihide*; Shimazu, Akira*; Fujinami, Masanori*; Hirade, Tetsuya; Saito, Haruo*; et al.

no journal, , 

For making a standard sample of positron annihilation measurement, quartz glass and polycarbonate were measured with 12 apparatus at AIST, Chiba Univ., Tokyo Univ., Tsukuba Univ., Touhoku Univ., Tokyo Gakugei Univ. JAEA, Nitto Denko, and Toray Research Center. By regulating procedure for the measurement and data analysis the uncertainties of the positron annihilation lifetime obtained at different laboratories were significantly reduced.

Oral presentation

Interlaboratry comparison of psotitron annihilation lifetime measurement

Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.

no journal, , 

So far no standard procedure for the positron annihilation lifetime (PAL) technique has been established. A lack of the standards has led to difficulty in ensuring equivalency and reliability of data from different laboratories. Recently, as a first step toward the standardization of the PAL technique, we conducted an interlaboratory comparison of PAL measurements for fused silica, polycarbonate and metal with agreed procedures for data recording and analysis. Based on the results of the reported lifetimes, possible sources of the uncertainties in the PAL measurements is probably caused by the backscattered $$gamma$$-rays by other detectors. We succeeded to show that inserting shields between detectors can reduce the uncertainty.

Oral presentation

Estimation of measurement uncertainty for positron annihilation lifetimes at an interlaboratory comparison

Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.

no journal, , 

An interlaboratory comparison for positron annihilation lifetime measurements for pure nickel, polycarbonate (PC) and fused silica was performed. Based on the reported data of positron (for nickel) and positronium (for PC and fused silica) components, the uncertainties in the PAL measurements were estimated and their possible source was discussed.

7 (Records 1-7 displayed on this page)
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