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Your search keyword '"Ukai, S."' showing total 174 results
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174 results on '"Ukai, S."'

24. List of contributors

Author

Aitkaliyeva, A., primary, Allen, T., additional, Asayama, T., additional, Bai, X.M., additional, Balbaud, F., additional, Blat-Yrieix, M., additional, Buckthorpe, D., additional, Cabet, C., additional, Dalle, F., additional, David, P., additional, de Carlan, Y., additional, Dubiez-Le Goff, S., additional, Dubuisson, Ph., additional, Fazio, C., additional, Gosset, D., additional, Guzonas, D., additional, Hall, G.N., additional, He, L., additional, Henry, J., additional, Ignatiev, V., additional, Jones, A.N., additional, Kaito, T., additional, Le Flem, M., additional, Malaplate, J., additional, Maloy, S.A., additional, Marsden, B.J., additional, Miller, B., additional, Mummery, P.M., additional, Muroga, T., additional, Novotny, R., additional, Ohtsuka, S., additional, Park, J.Y., additional, Penttilä, S., additional, Ribis, J., additional, Rouillard, F., additional, Sauzay, M., additional, Séran, J.-L., additional, Surenkov, A., additional, Treifi, M., additional, Ukai, S., additional, Wen, H., additional, and Zinkle, S.J., additional

Published
2017
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30. Microstructure and mechanical properties of mechanically alloyed ODS copper alloy for fusion material application

Author

Aghamiri, S.M.S., Oono, N., Ukai, S., Kasada, R., Noto, H., Hishinuma, Y., and Muroga, T.

Subjects
ODS copper, Mechanical properties, Mechanical alloying, Microstructure
Abstract

Advanced oxide dispersion strengthened copper alloys are promising structural materials for application in divertor system of future fusion reactors due to high irradiation resistance, high thermal conductivity, and good mechanical properties. In this study, a new ODS copper including 0.42wt%Y₂O₃ nanosized oxide particles was developed successfully by mechanical alloying method using addition of 1 wt% Stearic acid in Ar atmosphere. Mechanical alloying resulted in decrease of crystallite size to 28 nm in concurrent with increment of dislocation density and hardness to the saturated level of 1.7 × 10¹⁵m⁻² and 226HV₀.₁ after 48 h milling, respectively. Consolidated ODS copper by SPS and then hot roll-annealing at 900°C/60 min showed an average grain size of 1.1 µm with a near random texture. Furthermore, TEM observations demonstrated fine semicoherent Y₂O₃ oxide particles distributed with a misfit parameter (δ) of 0.17 in copper matrix with an average size of 10.8 nm and interparticle spacing of 152 nm. Finally, tensile test evaluation determined comparable mechanical properties of the annealed ODS copper (Cu-0.42wt%Y₂O₃) with Glidcop-Al25 including a yield strength of 272 MPa and total elongation of 12%, by two mechanisms of grain boundary strengthening and oxide particle strengthening.

Published
2018

43. Evaluation of Processing Conditions on the γ′ Morphology of an Oxide Dispersion Strengthened Ni‐Based Superalloy.

Author

Aghamiri, S. M. S., Linye, Z., Ukai, S., Oono, N., Shahverdi, H. R., and Soltanieh, M.

Subjects
DISPERSION strengthening, NICKEL alloys, HEAT resistant alloys, SCANNING transmission electron microscopy, HEAT treatment, MECHANICAL alloying
Abstract

Herein, the evolution of the microstructure of a newly developed oxide dispersion strengthened (ODS) Ni‐based superalloy with emphasis on γ′ morphology during different processing conditions is investigated. X‐ray analysis of severely deformed mechanically alloyed (MAed) powders shows that the as‐milled nano‐sized crystallite size increases with annealing associated with the sharp drop of dislocation density. At the same time, by annealing MAed powders γ′ precipitates above 300 °C, and depending on the aging treatment regime, Vickers microhardness changes mainly due to γ′ distribution and dislocation release. The thorough evaluation of γ′ morphology in the microscale shows that in contrast to the spherical shape of γ′, after heat treatment of solutionized MAed ODS superalloy, irregular‐shaped γ′ exist in the MAed ODS superalloy due to severe plastic deformation during mechanical alloying. However, a unique nanostructured lamellar morphology forms in the γ′ precipitates with different lamellae directions. This structure is stable in all subsequent processing steps with γ′ lamellae of (011¯) planes and intervals of 20–30 nm. The scanning transmission electron microscopy (STEM)–high‐angle annular dark‐field (HAADF) composition analysis clarifies that the nanostructured lamellar morphology shows no partitioning of alloying elements, and its origin may be attributed to the formation of antiphase domain boundaries. [ABSTRACT FROM AUTHOR]

Published
2021
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