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Matsukawa, Yoshitaka*; Kakubo, Yuta*; Nozawa, Yasuko*; Toyama, Takeshi*; Nagai, Yasuyoshi*; Takeuchi, Tomoaki; Yamaguchi, Yoshihito; Katsuyama, Jinya; Nishiyama, Yutaka
no journal, ,
The 
/
duplex stainless steel overlay-welded on the inner wall of light-water reactor pressure vessels for protection from corrosion is known to exhibit a complex phase transformation under thermal aging. Our atom-probe tomography analysis revealed that in the -ferrite 
/' spinodal decomposition and precipitation of nanometer-sized Ni-Mn-Si clusters occur together at 673 K after 2000 hrs. The Ni-Mn-Si clusters visualized in the 3-D atom map are most likely G-phase, which is an intermetallic compound commonly observed in this type of duplex stainless steels; however, since crystallographic information is largely lost in atom-probe data, it is unknown if they are certainly G-phase accompanied with a specific supper-lattice structure or simple agglomerates of solute atoms without any crystal structure change. In the present study crystal structure of the Ni-Mn-Si nano-clusters has been analyzed by transmission electron microscopy to determine the fraction of G-phase over all clusters.
Kakubo, Yuta*; Nozawa, Yasuko*; Matsukawa, Yoshitaka*; Toyama, Takeshi*; Nagai, Yasuyoshi*; Kameda, Jun; Takeuchi, Tomoaki; Yamaguchi, Yoshihito; Katsuyama, Jinya; Nishiyama, Yutaka; et al.
no journal, ,
no abstracts in English
double-prime (Ni
Nb) in the high Ni steelSano, Keisuke*; Ono, Naoko*; Ukai, Shigeharu*; Hayashi, Shigenari*; Miura, Seiji*; Yamashita, Shinichiro; Inoue, Toshihiko
no journal, ,
JAEA is study in the high Ni-alloy behavior as ODS substitute materials for the use in fast reactor. The precipitation behavior of double-prime (NiNb) in the high Ni steel was tested in prescription examinations. The results was the double-prime (NiNb) became a fault size and the hardness was decreased in the high prescription temperature and the long prescription time.
-FeSuzudo, Tomoaki; Tsuru, Tomohito; Yamaguchi, Masatake
no journal, ,
In the condition of severe accidents or fusion device environment, structural materials are exposed to radiation in high temperatures, and this condition easily causes grain boundary (GB) bubbles that lead materials to embrittlement. In the present study, to investigate the mechanism of nucleation of GB bubbles, we conducted a series of analyses of He-vacancy clusters, i.e. micro bubbles, at GBs using empirical potentials. First, we created Fe crystal systems that include various types of GBs and inserted He-vacancy clusters at the GBs. Second, we calculated the formation energy of the clusters and the binding energy of He (and vacancy) to the clusters. We found that the formation energy of the clusters in GBs is generally lower than those in the bulk, and that the equilibrium He-vacancy ratio of the clusters tend to increase in the GBs in comparison with those in the bulk.
-iron; Cluster dynamics modelingAbe, Yosuke; Tsuru, Tomohito; Jitsukawa, Shiro
no journal, ,
In this study, in addition to adequately model the 1D reaction kinetics of SIA loops in the framework of a production bias model, reaction kinetics associated with carbon impurity atoms present in -iron have been formulated to take into account the trapping effect of glissile SIA loops by vacancy-carbon (V-C) complexes. Results of calculated defect accumulation behavior of neutron irradiated -iron show that the developed CD model can successfully reproduce the number density of SIA loops when the applied impurity concentration is the same order as experimental one. The dependence of dose rate is discussed in detail.
Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori
no journal, ,
no abstracts in English