Kyushu University Academic Staff Educational and Research Activities Database
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Ozaki Yukiko Last modified date:2023.11.13

Professor / Department of Materials Science and Engineering,Faculty of Engineering
Department of Materials Science and Engineering
Faculty of Engineering

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Academic Degree
Country of degree conferring institution (Overseas)
Field of Specialization
Powder Metallurgy, Magnetic Materials
Total Priod of education and research career in the foreign country
Research Interests
  • 1) Analysis of intrinsic fracture mechanism of porous materials by 3D observation using X-ray CT.
    2) Creating heterogeneous sintered steel with reguiard to both strength and toughness.
    3) Thermodynamic analysis of alpha- /beta- relaxation process observed in metallic glasses, and proposal of low energy deformation process by promoting these atomic relaxations.
    4) Analysis of coercivity in powder iron magnetic core.
    keyword : 3D structure,metallic glass, sintered materials, powder magnetic core
Academic Activities
1. Isshin Ando, Kentaro Kudo, Kyosuke Hirayama, Yuji Shigeta, Kazunari Shinagawa, Akihisa Takeuchi, Masayuki Uesugi, Yukiko Ozaki, Quantitative estimation of contribution of pore size and the distance between nearest neighbour pores on high cycle fatigue (HCF) crack initiation in Ti-6Al-4V MIM-sintered materials, International Journal of Fatigue,, 171, 107557, 2023.02, The fatigue damages due to pores of MIM-sintered Ti64 were investigated using the synchrotron X-ray CT imaging. The effect of pores on the fatigue strength limits was analysed independently from that of grain size by introducing the fatigue limit ratio RF. The pores near to the maximum-stress area were identified by elastic FEM. The maximum stress intensity factor KImax at the edge of the identified pores showed a negative correlation with RF. Moreover, the initial cleavage in the crack was influenced by the mutual interference of both stress fields by the proximity of the identified pore and its adjacent pores..
2. Isshin Ando, Yasutaka Mugita, Kyosuke Hirayama, Shinji Munetoh, Fei Jiang, Takeshi Tsuji, Akihisa Takeuchi, Masayuki Uesugi and Yukiko Ozaki, Elucidation of pore connection mechanism during ductile fracture of sintered pure iron by applying persistent homology to 4D images of pores: Role of open pore, Materials Science and Engineering A, 2021.09.
3. Muhammad KOZIN, Keisuke KUSAKABE,Masatoshi ARAMAKI, Naoya YAMADA5, Satoshi OUE, Yukiko OZAKI, Osamu FURUKIMI and Masaki TANAKA, Effect of Nitriding-Quenching and Carburizing-Quenching Processes on the Wear Resistance
of Sintered Pure Iron., 粉体および粉末冶金,, 67, 4, 173-181, 2020.04.
4. Y. Ozaki, Y. Mugita, M. Aramaki, S. Ooue, O. Furukimi, F.Jiang, T.Tsuji, A. Takeuchi, M. Uesugi and K. Ashizuka, Four-dimensional (4D) Observation of Ductile Fracture in Sintered Iron using Synchrotron X-ray Laminography., Powder Metallurgy, 10.1080/00325899.2019.1585032, 62, 2, 145-154, 2019.02, [URL].
5. Y. Ozaki, Y. Mugita, M. Aramaki, S. Ooue, O. Furukimi, F.Jiang, T.Tsuji, A. Takeuchi, M. Uesugi and K. Ashizuka, Four-dimensional (4D) Observation of Ductile Fracture in Sintered Iron using Synchrotron X-ray Laminography., EPMA, EuroPM2018 Proceedings, EP1803982667., 2018.10.
6. Takashita Takuya, Nakamura Naomichi, Ozaki Yukiko, Influence of Particle Shape on Microstructure and Magnetic Properties of Iron Powder Cores, Material Transactions,, 57, 11, 1859-1867, 2016.09.
7. Unami Shigeru, Uenosono Satoshi, Ozaki Yukiko, Fatigue strength of sintered and carburized compacts made of molybdenum hybrid-alloyed steel powder., Adv. Powder Merall. Part. Mater. ,, 10, 56-65, 2016.07.
8. Ozaki Yukiko, Takamuya Tsuguyuki, Ono Tomoshige, Mechanisms of stick-slip vibration during warm compaction of iron powder., Adv. Powder Merall. Part. Mater., 01.10-01.18, 2015.09.
9. Ono Tomoshige, Sato Takanori, Ozaki Yukiko, Approach for reducing variation in weight of PM green parts in mass productive pressing line by addition of nanoparticle to raw material powder., Adv. Powder Merall. Part. Mater., 21, 03.26-03.33, 2014.09.
10. Maetani Toshio, Unami Shigeru, Ozaki Yukiko, Effect of a Newly Developed Machinability Aid on Machinability of Sintered Steels. , Powder Metallurgy World Congress & Exhibition. Yokohama, Japan (CD-ROM). 2012,, P-T7-74., 2012.12.
11. Ozaki Yukiko, Uenosono Satoshi, Tagami N, Noda Reiji, Horio Masayuki, Kuwagi Kenji, Experimental and numerical investigations of the die filling of iron powders., Adv. Powder Metall. Part. Mater., 1, 3.35-3.46, 2006.09.
12. Ozaki Yukiko, Uenosono Satoshi, Ogura Kuniaki, An analysis of the compaction behaviors of iron powders during warm compaction., Adv. Powder Merall. Part. Mater., 1, 2.109-2.155, 1999.09.
1. Nakamura Koji , Ando Isshin, Hirayama Kyosuke, Aramaki Masatoshi, Jiang Fei, Tsuji Takeshi, Ashizuka Kosuke, Uesugi Masayuki, Takeuchi Akihisa, Ozaki Yukiko, Analysis of the Mechanism of Ductile Crack Initiation in High Density Sintered Iron - Visualization and Quantification of the 3D Pore-configurations by Synchrotron X-ray Tomography and Persistent Homology, WorldPM2022, 2022.10.
2. Yuji Shigeta , Masatoshi Aramaki, Kentaro Kudo, Kazunari Shinagawa, Naoyuki Nomura, Katsuyoshi Kondoh, Masato Hoshino, Kentaro Uesugi, Yukiko Ozaki, Understanding the effect of process parameters on three-dimensional pore configurations and mechanical properties of laser additive manufactured Ti using synchrotron X-ray computed tomography and homology, WorldPM2022, 2022.10.
3. Yukiko Ozakia, Yasutaka Mugita, Masatoshi Aramaki, Satoshi Ooue, Kosuke Ashizukab, Akihisa Takeuchi, Masayuki Uesugi and Osamu Furukimia, Four-dimensional (4D) Observation of Ductile Fracture in Sintered Iron using Synchrotron X-ray Laminography , EuroPM 2018 Conference and Exhibitions, Birbao, 2018.10, Using synchrotron X-ray laminography, time evolution of the 3-dimensional (3D) morphology of micropores in sintered iron during a tensile test is revealed for the first time. The 3D snapshots showed networked open pores growing wider than 20 m of width along the tensile direction, resulting in the internal necking of the specimen. Finally, the enlarged-open pores initiated cracks perpendicular to tensile direction by coalescing with surrounding micro-voids pre-existent or secondary generated just before fracture. Therefore, by the topological analysis of their barycentric positions, these micro-voids formed 2-demensional networks in the area within about 20 m round. It indicates that coalescence of micro-voids could occur on share planes formed close to the enlarged-open pore by strain accumulation and play an important role in the crack-initiation..
4. Muhammad Kozin, Naoya Yamada, Masatoshi Aramaki, Yukiko Ozaki ,Osamu Furukimi, Wear Resistance of Sintered Pure Iron Treated by Acetylene Gas Carburizing Process, JSPM International Conference on Powder and Powder Metallurgy 2017 ~60th Anniversary, 2017.11, The wear resistance without lubrication of sintered pure iron treated by vacuum carburizing process was investigated. The sliding test results revealed that the wear volume of the specimen treated by the C2H2 gas carburizing decreased about 75% in comparison with the one without the heat treatment. The wear profile observation by Laser microscope of friction surface for the specimen treated by the C2H2 gas carburizing was seemed to be a relatively shallow. In contrast, in specimen without the heat treatment, the relatively deep valley was observed. In addition, a micro-ploughing track and relatively deep scar parallel to the sliding direction which is the characteristic of abrasive wear were observed in the specimen without the heat treatment. Nano-indentation hardness at near the surface of the specimen treated the C2H2 gas carburizing increased from value of HIT amounted to 1751 N/mm2 before heat treatment to 7699 N/mm2 after the heat treatment. The EBSD analysis results showed that the carburized layer consisted of a tempered martensitic phase and a small amount of a retained austenite phase. From these results, it can be concluded that the enhanced wear resistance of the C2H2 gas carburizing specimen is attributed to the increase in the hardness due to the presence of the martensitic phase layer at the surface. This layer is considered to inhibit the surface degradation due to micro-ploughing or exfoliation resulting in a high wear rate..
5. Takashita,Takuya, Nakmaura, Naomichi, Ozaki, Yukiko, Influence of Microstructure on Hysteresis Loss of Pure Iron Powder Core., World PM2016 Congress & Exhib, 2016.10, [URL].
6. Maetani,Toshio, Unami,Shigeru, Ozaki,Yukiko, Yamanichi,Y., Properties of sintered compacts and heat-treated compacts after sintering made of low Cr prealloyed steel powder. , Euro PM 2013, 2013.09.
7. Maetani,Toshio, Unimi,Shigeru, Ozaki, Yukiko, Effect of a Newly Developed Machinability Aid on Machinability of Sintered Steels., Powder Metallurgy World Congress & Exhibition., 2012.10.
8. Shimotomai,M., Fukuda,Y., Fujita,A., Ozaki,Y., Corrosion-Resistant Nd-TM-B Magnet., INTERMAG '90, 1990.09.
9. Takajyo,S., Ozaki,Y., Frequency dependence of the permeability and iron loss of iron powder dust cores for high frequency applications. Power Convers., Motion HFPC Conf. 1998, 1998.09.
Membership in Academic Society
  • Europian Powder Metallurgy Association (EPMA)
Other Educational Activities
  • 2016.09.