HOME > Profile > KITASHIMA, Tomonori
- Address
- 305-0047 1-2-1 Sengen Tsukuba Ibaraki JAPAN [Access]
Accepting Students
External affiliations
- Professor, Department of Materials, Kyushu University
Research
- Keywords
single crystal and crystallographic texture, structure–property relationship, phase transformation, additive manufacturing, high-temperature metallic materials
3D Printing Nickel Single Crystals Using Laser Additive Manufacturing Technology
We have succeeded in fabricating single crystals by laser powder bed fusion using a flat-top laser beam, which produces a flat melt pool surface in nickel powder. Individual crystalline grains grow in the same direction, resulting in fewer strain-inducing defects. Single crystals without grain boundaries, which are susceptible to cracking, exhibit high strength at elevated temperatures. This new technique minimizes strain generation and cracking during solidification. In addition, it does not require the use of seed crystals, thereby simplifying the additive manufacturing process.
PH.D. OPENINGS
Highly motivated students are sought for a PhD program at Kyushu University, focusing on metallic materials and powder-based additive manufacturing (3D printing).
Doctoral students take primary responsibility for their research projects and are expected to develop original research themes leading to first-author publications in international peer-reviewed journals.
Research in the laboratory focuses on microstructure control and design, which requires a clear understanding of how microstructures form during processing. The goal is to establish a scientific basis for process design by clarifying how processing parameters govern microstructural evolution and material properties. Recent work emphasizes laser-based additive manufacturing, integrating experiments, advanced characterization, and simulations. Research topics may build on prior master’s-level work, but can also be newly designed through discussion, taking into account the student’s background, interests, and the scope of ongoing projects in the group, as well as emerging scientific challenges.
Research is conducted primarily at the National Institute for Materials Science (NIMS) in Tsukuba, and doctoral students are expected to be based in Tsukuba during the PhD program in order to engage fully in research activities. The work makes extensive use of research facilities and interdisciplinary infrastructure available at NIMS, including access to world-leading research instrumentation. NIMS offers an international research environment with daily interactions among researchers from diverse backgrounds, supporting high-quality research and publication.
Financial support programs at NIMS are available to eligible doctoral students who participate as research staff, enabling them to focus on their doctoral research.
https://www.nims.go.jp/kyushu/en/junior/
[Latest NEWS]
The 4th Asia-Pacific International Conference on Additive Manufacturing (APICAM) 2025 (1-3 July, Melbourne, Australia)
Invited talk regarding the effect of heat treatment on the single-crystal structure fabricated by LPBF.
The 11th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN) 2024 (22-25 September, Da Nang, Vietnam)
Invited talk regarding the single-crystal-structure fabrication of metals in LPBF.
Alloys for Additive Manufacturing Symposium (AAMS) 2024 (4-6 September, Palaiseau, France)
Oral presentation regarding the single-crystal-structure fabrication and unique variant selection of Ti-6246 in LPBF.
TMS 2024 (3–7 March 2024, Florida, USA)
Two oral presentations regarding the single crystal growth in LPBF.
THERMEC' 2023 (2–7 July 2023, Vienna, Austria)
Two presentations (one is invited).
Ti-2023 (12–16 June 2023, Edinburgh, UK)
Two oral presentations.
TMS 2023 (19–23 March 2023, San Diego, USA)
Three presentations.
[Selected Articles!]
Single-crystal β-Ti–42Nb fabricated via flat-top laser powder bed fusion: melt-pool stability–controlled cellular-dendritic growth
Xinzhe Zhu, Kohei Araake, Toshihiro Tsuchiyama, Makoto Watanabe, Tomonori Kitashima, Materials & Design, Vol. 270, (2026) 116896.（Click and open）
Fabricating a single-crystal-like beta grain structure of a near-beta Ti alloy with unique variant selection by laser powder bed fusion
T. Kitashima, T. Hiroto, D.E. Jodi, M. Watanabe, Materials & Design, Vol. 243, (2024) 113039.（Click and open）
Effect of scan strategy on the formation of a pure nickel single-crystal structure using a flat-top laser beam via laser powder bed fusion
D. E. Jodi, T. Kitashima, M. Watanabe, Science and Technology of Advanced Materials, Vol. 24, (1), (2023) 2201380.（Click and open）
High-temperature microstructural stability of pure Ni fabricated by laser powder bed fusion using Gaussian and flat-top beam profiles
D. E. Jodi, T. Kitashima, A. Singh, M. Watanabe, Materials Characterization, Vol. 200 (2023) 112897.（Click and open）
We have succeeded in fabricating single crystals by laser powder bed fusion using a flat-top laser beam, which produces a flat melt pool surface in nickel powder. Individual crystalline grains grow in the same direction, resulting in fewer strain-inducing defects. Single crystals without grain boundaries, which are susceptible to cracking, exhibit high strength at elevated temperatures. This new technique minimizes strain generation and cracking during solidification. In addition, it does not require the use of seed crystals, thereby simplifying the additive manufacturing process.
PH.D. OPENINGS
Highly motivated students are sought for a PhD program at Kyushu University, focusing on metallic materials and powder-based additive manufacturing (3D printing).
Doctoral students take primary responsibility for their research projects and are expected to develop original research themes leading to first-author publications in international peer-reviewed journals.
Research in the laboratory focuses on microstructure control and design, which requires a clear understanding of how microstructures form during processing. The goal is to establish a scientific basis for process design by clarifying how processing parameters govern microstructural evolution and material properties. Recent work emphasizes laser-based additive manufacturing, integrating experiments, advanced characterization, and simulations. Research topics may build on prior master’s-level work, but can also be newly designed through discussion, taking into account the student’s background, interests, and the scope of ongoing projects in the group, as well as emerging scientific challenges.
Research is conducted primarily at the National Institute for Materials Science (NIMS) in Tsukuba, and doctoral students are expected to be based in Tsukuba during the PhD program in order to engage fully in research activities. The work makes extensive use of research facilities and interdisciplinary infrastructure available at NIMS, including access to world-leading research instrumentation. NIMS offers an international research environment with daily interactions among researchers from diverse backgrounds, supporting high-quality research and publication.
Financial support programs at NIMS are available to eligible doctoral students who participate as research staff, enabling them to focus on their doctoral research.
https://www.nims.go.jp/kyushu/en/junior/
[Latest NEWS]
The 4th Asia-Pacific International Conference on Additive Manufacturing (APICAM) 2025 (1-3 July, Melbourne, Australia)
Invited talk regarding the effect of heat treatment on the single-crystal structure fabricated by LPBF.
The 11th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN) 2024 (22-25 September, Da Nang, Vietnam)
Invited talk regarding the single-crystal-structure fabrication of metals in LPBF.
Alloys for Additive Manufacturing Symposium (AAMS) 2024 (4-6 September, Palaiseau, France)
Oral presentation regarding the single-crystal-structure fabrication and unique variant selection of Ti-6246 in LPBF.
TMS 2024 (3–7 March 2024, Florida, USA)
Two oral presentations regarding the single crystal growth in LPBF.
THERMEC' 2023 (2–7 July 2023, Vienna, Austria)
Two presentations (one is invited).
Ti-2023 (12–16 June 2023, Edinburgh, UK)
Two oral presentations.
TMS 2023 (19–23 March 2023, San Diego, USA)
Three presentations.
[Selected Articles!]
Single-crystal β-Ti–42Nb fabricated via flat-top laser powder bed fusion: melt-pool stability–controlled cellular-dendritic growth
Xinzhe Zhu, Kohei Araake, Toshihiro Tsuchiyama, Makoto Watanabe, Tomonori Kitashima, Materials & Design, Vol. 270, (2026) 116896.（Click and open）
Fabricating a single-crystal-like beta grain structure of a near-beta Ti alloy with unique variant selection by laser powder bed fusion
T. Kitashima, T. Hiroto, D.E. Jodi, M. Watanabe, Materials & Design, Vol. 243, (2024) 113039.（Click and open）
Effect of scan strategy on the formation of a pure nickel single-crystal structure using a flat-top laser beam via laser powder bed fusion
D. E. Jodi, T. Kitashima, M. Watanabe, Science and Technology of Advanced Materials, Vol. 24, (1), (2023) 2201380.（Click and open）
High-temperature microstructural stability of pure Ni fabricated by laser powder bed fusion using Gaussian and flat-top beam profiles
D. E. Jodi, T. Kitashima, A. Singh, M. Watanabe, Materials Characterization, Vol. 200 (2023) 112897.（Click and open）
PublicationsNIMS affiliated publications since 2004.
Research papers
- Xinzhe Zhu, Kohei Araake, Toshihiro Tsuchiyama, Makoto Watanabe, Tomonori Kitashima. Single-crystal β-Ti–42Nb fabricated via flat-top laser powder bed fusion: melt-pool stability–controlled cellular-dendritic growth. Materials & Design. 270 (2026) 116896 10.1016/j.matdes.2026.116896 Open Access
- Dennis Edgard Jodi, Tomonori Kitashima, Yuichiro Koizumi, Takayoshi Nakano, Makoto Watanabe. Manufacturing single crystals of pure nickel via selective laser melting with a flat-top laser beam. Additive Manufacturing Letters. 3 (2022) 100066 10.1016/j.addlet.2022.100066 Open Access
- T. Kitashima, H. Harada. A new phase-field method for simulating gamma-prime precipitation in multi-component nickel-base superalloys. Acta Materialia. 57 [6] (2009) 2020-2028 10.1016/j.actamat.2009.01.006
Books
Proceedings
- KITASHIMA, Tomonori, JODI, Dennis Edgard, WATANABE, Makoto. Microstructure and crystallographic texture of a near-beta titanium alloy fabricated by laser powder bed fusion with a flat-top laser beam. Proceedings of the 15th World Conference on Titanium. Chapter 2 (2024) 47-51
- 北嶋 具教, ジョディ デニス エドガード, 渡邊 誠. フラットトップレーザ粉末床溶融結合法におけるニッケル単結晶の造形に不可欠なレーザスキャンストラテジー. 第51回日本ガスタービン学会定期講演会講演論文集. n/a (2023) A-15
- KITASHIMA, Tomonori, MITARAI, Yoko, IWASAKI, Satoshi, KURODA, Shuji. Effects of alloying elements on tensile and oxidation properties in α and near-α Ti alloys. Proceedings of The 13th World Conference on Titanium (Ti-2015) . (2016) 479-483
Presentations
- KITASHIMA, Tomonori, 荒明 晃平, HIROTO, Takanobu, ZHU, Xinzhe, WATANABE, Makoto. Effect of β annealing on the single-crystal β-grain structure of a near-β Ti alloy fabricated by laser powder bed fusion. The 4th Asia-Pacific International Conference on Additive Manufacturing (APICAM) 2025. 2025 Invited
- KITASHIMA, Tomonori, 平賀 知輝, JODI, Dennis Edgard, KAWAGISHI, Kyoko, DEMURA, Masahiko, 日比野 真也, 中野 貴由, WATANABE, Makoto. Development of a γ’-strengthened Ni-base superalloy for laser powder bed fusion. TMS 2023 Annual Meeting. 2023
- KITASHIMA, Tomonori. Fabrication of a nickel single-crystal structure by controlling melt pool geometry in laser powder fusion with a flat-top laser beam. Thermec' 2023: International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS. 2023 Invited
Misc
- 北嶋 具教. ニッケル単結晶のレーザ積層造形. 金属. 93 [7] (2023) 561-567
- 北嶋 具教. レーザ3Dプリンタによるニッケル単結晶の造形法開発. 光アライアンス. 34 [6] (2023) 7-10
- 北嶋 具教. Numerical analysis of the stacking fault energy in a narrow γ channel of a Ru-bearing Ni-base superalloy. Proceedings of The 1st International Conference on 123HiMAT-2015. (2016) 285-288
Published patent applications
Society memberships
The Minerals, Metals & Materials Society (TMS), Japan Institute of Metals and Materials (JIMM), The Iron and Steel Institute of Japan (ISIJ), Japan Institute of Light Metals (JILM), The Japan Institute of Additive Manufacturing
Research Center for Structural Materials
Title
チタン合金とニッケル基超合金の組織制御と単結晶化
Keywords
チタン合金，ニッケル基超合金，積層造形，高温変形，組織制御，析出，相変態，集合組織，単結晶
Overview
チタン合金とニッケル基超合金は飛行機の機体やエンジンに使われており、それら材料の特性は飛行機の性能に大きく影響する。その材料特性を決定づけるのがミクロ組織と結晶粒構造である。粉末積層造形や高温加工、熱処理により従来報告されていないミクロ組織や結晶粒構造を創出し、材料特性の向上を図る。また、相変態、析出、集合組織形成、バリアント選択のメカニズムを解明し、その知見を組織制御の高度化に資する。近年では、高温強度に優れる単結晶を従来困難だったレーザ粉末積層造形で創製した。単結晶構造の形成メカニズムを解明し、積層造形体の積層設計に資する。
Novelty and originality
● レーザ粉末積層造形による金属材料の単結晶化と集合組織制御
● 熱処理による積層造形材の析出物形態とバリアント選択の制御
● レーザ粉末積層造形による高強度合金の創出
● 金属材料の高温変形時のミクロ組織形成と集合組織形成の制御
● 高温酸化における酸化物形成と酸素固溶の数値シミュレーション
Details
レーザ粉末積層造形でニッケル単結晶の造形に成功した。照射面強度分布が一様なフラットトップレーザを金属粉末に照射することで溶融領域が平坦になり、造形方向に単結晶構造の成長を促進する。また、単結晶の造形にはレーザの走査方向が重要な役割を担っており、レーザ走査面で走査方向をレイヤー毎に90°回転させることで、走査面全体で単結晶が成長する。この技術をチタン合金に展開し、チタン合金でも同様に単結晶構造が得られることを実証した。さらに、熱処理により単結晶の析出物を特異な析出形態に制御できる方法を見出した。今後、単結晶造形技術がさらに他の金属や合金に展開され、高機能化や高温強度の向上につながることが期待される。
Summary
従来困難だったレーザ粉末積層造形で、高温で結晶構造が安定なニッケル単結晶の造形に成功した。この単結晶造形技術をチタン合金に展開し、チタン合金でも同様に単結晶を造形し、熱処理により析出物を特異な形態に制御することに成功した。単結晶は高温強度に優れ、また、異方性材料でもある。この造形技術が様々な金属や合金に展開されることが期待される。
この機能は所内限定です。
この機能は所内限定です。