TEM observation and EELS measurement of ZrC coating layer for advanced high temperature gas cooled reactor

Aihara, Jun; Ueta, Shohei; Motohashi, Yoshinobu*; Sawa, Kazuhiro

no journal, , 

Development of ZrC coated fuel particles for advanced high temperature gas cooled reactors. As a basic study, the ZrC coating layer has been fabricated using the bromide process at JAEA. The coated particles were annealed at around 1800 C for 1h, under which compact sintering will be done in a practical process, in order to study effects of the heat treatment on their microstructure evolution. Then the microstructures of the ZrC layers in the batch of C/Zr = 1.35 were characterized by means of TEM. Certain changes in the shape and size of voids or free carbons region caused by the heat treatment were found. After the heat treatment, the voids or free carbons region have changed from a thin layered feature into a clod like feature with diameters of 50 to 100 nm. In addition, EELS measurements were carried out in the heat treated specimen. The * peak of carbon was observed in the spectrum from free carbons or voids region, but not in the spectrum from ZrC region.

Corrosion test in lead-bismuth for SUS316 with Al powder alloy coating

Kurata, Yuji; Sato, Hidetomo*; Yokota, Hitoshi*; Suzuki, Tetsuya*

no journal, , 

Liquid lead-bismuth is a candidate material used for accelerator driven systems and fast reactors. Development of corrosion resistant materials in liquid lead-bismuth is one of important research subjects to realize these systems. In this study improvement of corrosion resistance of 316SS was investigated by means of aluminum powder alloy coating. Aluminum alloys were coated on 316SS using sheets made of Al, Ti and Fe powders, and laser heating. The corrosion test was conducted at 550C for 1000h in liquid lead-bismuth where oxygen concentrations were controlled to be about 510mass%. As a result of the corrosion test, it was found that Al alloy coating protected grain boundary corrosion and surface oxidation of Fe and Cr, which were significant in 316SS substrate.

Formation of ferromagnetic phase in nuclear grade austenitic stainless steel and evaluation based on system free energy

Shintani, Tsuyoshi*; Tsukada, Yuki*; Shiraki, Atsuhiro*; Murata, Yoshinori*; Morinaga, Masahiko*; Takaya, Shigeru; Koyama, Toshiyuki*

no journal, , 

The magnetic flux density of SUS316 changes lesser than that of SUS304 during creep deformation. In this study, the reason of this difference was investigated based on system free energy. As result, it was revealed that the strain energies of both steels, which contribute to the formation of ferromagnetic bcc phase, were almost the same. Therefore, the dependency of magnetic flux density change on steel grades will be related to that activation energy for the formation of ferromagnetic phase of SUS316 is larger than that of SUS304.

Correlation between the coercivity and the averaged internal structures of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets studied by small-angle neutron scattering measurements, 2

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

We have been investing the correlation between the coercive force and the averaged internal structure of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets using the small-angle neutron scattering (SANS) spectrometer, SANS-J-II installed at the beam hall of the research reactor JRR-3 in Tokai. The correlation is a clue to achieve the less or Dysprosium (Dy)-free Nd-Fe-B sintered magnets with high coercivity for high-temperature application. In this talk, we report that the coercivity is very sensitive to the averaged diameter of powder and the temperature in sintering process, and that the SANS patterns on 2-dimensional position-sensitive detector (2D-PSD) are also sensitively changed following the sintering condition.

Dependence evaluation on grain boundary characteristic for corrosion effects after irradiaion

Endo, Masaki*; Sakaguchi, Norihito*; Kinoshita, Hiroshi*; Watanabe, Seiichi*; Kokawa, Hiroyuki*; Yamashita, Shinichiro; Yano, Yasuhide; Kawai, Masayoshi*

no journal, , 

no abstracts in English

Microstractural evolution under irradiation predicted by cluster dynamics

Abe, Yosuke; Jitsukawa, Shiro

no journal, , 

Using the cluster dynamics (CD) simulation, the effects of the mobility of large SIA loops on the development of the microstructure are examined under cascade irradiation condition. The obtained SIA and vacancy clusters as well as the cluster size distributions depending on the damage level are compared with results by experiments in -iron. It was shown that for mobile clusters up to three, the saturation versus dose is clearly not reproduced for both SIA and vacancy cluster densities because defect clusters are continuously produced by cascade damage but large SIA clusters do not migrate and annihilated at sinks. Therefore, taking the mobility of SIA clusters of all sizes into account in CD simulation is necessary to successfully reproduce the saturation trend of SIA cluster density as a function of irradiation dose.

First-principles calculations of grain boundary cohesive energy, 2; Hydrogen embrittlement of iron

Yamaguchi, Masatake; Ebihara, Kenichi; Itakura, Mitsuhiro; Suzudo, Tomoaki; Kaburaki, Hideo; Kadoyoshi, Tomoko*

no journal, , 

It is not known in detail how much hydrogen atoms can be trapped in grain boundaries of metals and how much the cohesive energy (work of fracture) of grain boundary is decreased by the hydrogen trapping. From first-principles, we calculated the trapping energy of hydrogen atoms in bcc Fe Sigma 3 (111) symmetrical tilt grain boundaries and on the fracture surfaces with varying the trapping density of hydrogen. We find that hydrogen atoms can be trapped up to a high concentration in the grain boundaries and on the fracture surfaces for Fe. We also find that the trapping energy on the surface is significantly larger than that in the grain boundary. The cohesive energy of the grain boundary is decreased by hydrogen trapping by about 30% at most. Moreover, the cohesive energy can be decreased by about 70% at most if hydrogen in solid solution state moves quickly and then adsorbs onto the newly generated fracture surfaces.

Creep deformation behavior of highly corrosion resistant ODS ferritic steels

Toda, Yoshiaki*; Hara, Toru*; Abe, Fujio*; Kimura, Akihiko*; Kasada, Ryuta*; Inoue, Masaki; Okuda, Takanari*; Onuki, Somei*; Ukai, Shigeharu*; Fujisawa, Toshiharu*

no journal, , 

no abstracts in English

Corrosion behavior of ODS ferritic steels made from elemental and pre-alloyed powders

Lee, J. H.*; Kasada, Ryuta*; Kimura, Akihiko*; Okuda, Takanari*; Inoue, Masaki; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*; Abe, Fujio*

no journal, , 

Synthesis and formation control of porous ceramics by the using of polysiloxane

Kita, Kenichiro; Narisawa, Masaki*; Nakahira, Atsushi*; Ito, Masayoshi*; Sugimoto, Masaki; Yoshikawa, Masahito

no journal, , 

no abstracts in English