Faculty Profiles - YAMAGUCHI Tomiko

Other Link： https://ci.nii.ac.jp/naid/130007806209

Growth Characteristics of Intermetallic Compounds on the Bond Interface of Magnesium-Clad Aluminum and Its Effect on Interface Properties Reviewed

Shu Jinfeng, Yamaguchi Tomiko

Journal of Light Metal Welding ( Japan Light Metal Welding Association ) 58 ( 0 ) 107s - 112s 2020.01

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

The Al/Mg clad materials were produced by vacuum roll bonding. After bonding, the clad materials were heat treated at different temperatures. The growth of intermetallic compounds on Al/Mg bond interface was investigated. The results show that the growth of intermetallic compounds was very slow at 200℃ and only Al3Mg2 layer with 2 μm thickness was observed after 3h. Al3Mg2 and Al12Mg17 intermetallic layers were formed at and above 300℃, and the growth activation energy of Al3Mg2 (86.18 kJ/mol) is smaller than that of Al12Mg17 (115.33 kJ/mol), so the growth of Al3Mg2 is faster and thicker. The thickness of intermetallic layer has a great influence on the tensile strength of Al/Mg interface. When the thickness of the intermetallic layer exceeded 20 μm, the tensile strength reduced to less than 6 Mpa. After 200℃ heat treatment, ductile fracture and brittle fracture occurred simultaneously at Al/Mg interface during tensile test. After heat treatment at and above 300℃, the fracture of Al/Mg interface occurred in the intermetallic layer and mainly in the Al3Mg2 layer, and the mode of fracture were cleavage fracture.

DOI： 10.11283/jlwa.58.107s

Other Link： https://ci.nii.ac.jp/naid/130007832378

Development of Partial Hardening Technology for Low Carbon Steel and Casting by Laser Irradiation Invited Reviewed

YAMAGUCHI Tomiko, MOURI Yoichi, KITAGAWA Yoshihiro

Journal of Jpan Laser Processing Society ( Japan Laser Processing Society ) 27 ( 3 ) 162 - 163 2020.01

Fabrication and characterization of Pr6O11-HfO2 ultra-high temperature infrared radiation coating Reviewed

39 ( 14 ) 4208 - 4215 2019.11

Fabrication and characterization of Pr<inf>6</inf>O<inf>11</inf>-HfO<inf>2</inf> ultra-high temperature infrared radiation coating Reviewed International journal

Liu F., Cheng X., Mao J., Li S., Shao H., Liu T., Yamaguchi T., Zeng X.

Journal of the European Ceramic Society 39 ( 14 ) 4208 - 4215 2019.11

Bond characteristics of Al/Mg clad materials produced by vacuum roll bonding Reviewed International journal

Shu J.F., Yamaguchi T.K.

IOP Conference Series: Materials Science and Engineering 576 ( 1 ) 2019.08

Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion Reviewed International journal

Mito M., Kitamura Y., Tajiri T., Nakamura K., Shiraishi R., Ogata K., Deguchi H., Yamaguchi T., Takeshita N., Nishizaki T., Edalati K., Horita Z.

Journal of Applied Physics 125 ( 12 ) 2019.03

Effect of creep degradation on hardness changes of Ni-based alloys for A-USC power boiler Reviewed International journal

Saito N., Ishiyama K., Yamaguchi T., Masuyama F.

ISIJ International ( The Iron and Steel Institute of Japan ) 59 ( 9 ) 1695 - 1704 2019.01

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

A project to develop Advanced Ultra-Supercritical (A-USC) power plant which operate at 700°C has been under way in Japan with the intension to reduce the CO2 emission and improve the power generation efficiency. Ni-based alloys, UNS N06674 (ASME Code Case 2826, 47Ni-23Cr-23Fe-7W, HR6W) and UNS N06617 (52Ni-22Cr-13Co-9Mo, Alloy 617) are candidate materials used in the high temperature regions of the A-USC power boilers. In this study, effect of creep degradation on the hardness change of both Ni-based alloys was investigated in order to evaluate the potential of the hardness method for creep life assessment. The investigation results showed that the scattering of hardness values in the latter stage of the creep life was increased as a result of hardening and softening of the material due to the increase of dislocation density with creep deformation and coarsening of precipitates followed by the formation of creep cavities, respectively. This tendency shows a good correlation with the creep life fraction. Therefore, it could be an useful tool for creep life evaluation. In addition, it was found that the hardness variation of the HR6W can be expressed as a function of temperature, stress and creep life fraction and thus leads to postulate a regression equation with hardness by a multivariate analysis. The creep life fraction can be calculated by substituting the values of service temperature and stress, and measured hardness into the multivariate regression equation. Those findings suggested that the hardness method was useful for the creep life assessment of Ni-based alloys.

DOI： 10.2355/isijinternational.ISIJINT-2018-878

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85072284245&origin=inward

HIGH TEMPERATURE OXIDATION BEHAVIOR OF HIGH NITROGEN FERRITIC STEELS Reviewed

Masuyama F., Matsubara S., Tonoe Y., Yamaguchi T.

Joint EPRI-123HiMAT International Conference on Advances in High-Temperature Materials - Proceedings from EPRI's 9th International Conference on Advances in Materials Technology for Fossil Power Plants and the 2nd International 123HiMAT Conference on High-Temperature Materials 282 - 293 2019.01

High temperature oxidation behavior of high nitrogen 9%cr steels Reviewed International journal

Matsubara Shoichi, Yamaguchi Tomiko, Masuyama Fujimitsu

ISIJ International ( The Iron and Steel Institute of Japan ) 58 ( 11 ) 2095 - 2101 2018.11

Language：English Publishing type：Research paper (scientific journal)

High temperature oxidation behavior of high nitrogen steel with about 0.3 mass% of nitrogen has been investigated comparing with nitrogen-free steels and ASME grade 91. High temperature oxidation tests were carried out in air over the temperature range 750 to 850°C for 300 h at maximum. Weight gain was measured and oxide scales were observed using an optical microscope and analyzed with an electron probe X-ray microanalyzer. It was found that the oxidation resistance of the high nitrogen steel is superior to that of nitrogen-free steels and ASME grade 91. Furthermore, Cr concentration in the oxide scale of the high nitrogen steel was higher than that in other steels. These results indicate high nitrogen promotes the formation of the oxide scale with high concentration of Cr inhibiting oxidation from proceeding in the high nitrogen steel.

DOI： 10.2355/isijinternational.ISIJINT-2018-246

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85056889582&origin=inward

Effect of Cr content and microstructure on high temperature oxidation behavior of high nitrogen heat-resistant ferritic steels Reviewed International journal

Matsubara Shoichi, Yamaguchi Tomiko, Masuyama Fujimitsu

ISIJ International ( The Iron and Steel Institute of Japan ) 58 ( 11 ) 2102 - 2109 2018.11

Language：English Publishing type：Research paper (scientific journal)

Effect of Cr content and microstructure on high temperature oxidation behavior of high nitrogen steels with 0.2–0.3 mass% of nitrogen has been investigated. For high temperature oxidation test 9–15%Cr high nitrogen steels are prepared. High temperature oxidation tests were carried out in air mainly at 800°C for 300 h at maximum. Weight gain was measured and oxide scales were observed using an optical microscope and analyzed with an electron probe X-ray microanalyzer. The addition of high nitrogen improved the oxidation resistance of 9–15%Cr high nitrogen steels. It was found that the oxidation resistance of the high nitrogen steels does not depend greatly on Cr content but on their microstructure. The oxidation resistance of high nitrogen ferritic heat-resistant steels increased as the fraction of martensite structure increased. These results indicate for high nitrogen steels Cr diffusion along grain boundaries is further promoted resulting in the formation of protective oxide scale having high Cr concentration.

DOI： 10.2355/isijinternational.ISIJINT-2018-247