Nakano Laboratory

【論文】PBF-LB/Mにより単結晶化度の高いIN738LCの作製に成功したことがMaterials & Design（Elsevier）に受理され、OA論文として掲載されました。

2026-05-13T08:08:38Z

Masayuki Okugawa*, Kazufumi Nose, Sei Hirooka, Sukeharu Nomoto, Yuheng Liu, Makoto Watanabe, Yuichiro Koizumi*, Takayoshi Nakano:
Fully single-crystallization of IN738LC Ni-based superalloy fabricated by laser powder-bed fusion through optimal thermal annealing,
Materials & Design, 266, (2026), 116222: 1-11.

DOI: https://doi.org/10.1016/j.matdes.2026.116222

論文はこちら
PDFはこちら

Abstract
The application of additive manufacturing (AM) to Ni-based superalloys has attracted considerable attention because it enables the production of high-temperature parts that are lighter, integrally formed, and less expensive. However, single-crystal fabrication of precipitation-hardened Ni-based superalloys using AM remains challenging. This study demonstrates that a single crystal (SX) of the IN738LC Ni-based superalloy can be fabricated via laser powder bed fusion (PBF-LB) and the quality of the built SX part can be improved via optimal thermal annealing. The as-fabricated part exhibits inhomogeneities in crystal orientation: the central area is a single crystal, whereas the edges are polycrystalline. The crystal orientation of the single-crystal region is largely affected by gas flow during the build, which could be detected by the in-process melt pool monitoring system. Additionally, significant solute-element segregation is observed in the microstructure of the single-crystal region, consistent with the distribution predicted by the multi-phase-field simulation. Notably, we found that anomalous grain growth, induced by optimal annealing at 1200 °C, selectively expands the SX region while eliminating solute-element segregation, thereby improving the overall quality of the single-crystal part. These findings provide insight into the development of single-crystal fabrication via the PBF-LB process for aerospace and energy applications.

keywords: Additive manufacturing; Laser powder bed fusion; Ni-based superalloy; Single-crystal fabrication; µ-Helix scan

【行事】中野研究室恒例の新入生歓迎BBQを行いました。

2026-05-09T11:23:42Z

中野研究室恒例の新入生歓迎BBQを服部緑地公園にて行いました。
OB, OGの方にも多数参加していただき、今年も非常に盛り上がりました。
今年はカンガルー肉をはじめとしたオリジナリティにあふれる食材も登場し、終始にぎやかで愉快なひとときとなりました！

【視察】3DPTec統合センターを、三菱重工（株）大宮名誉顧問殿（元会長・社長）ご一行が視察されました。

2026-05-07T23:51:36Z

3DPTec統合センターを、三菱重工（株）大宮名誉顧問殿（元会長・社長）ご一行が視察されました。

三菱重工（株）大宮名誉顧問（前列左から3番目）、有田執行役員（エネルギードメイン　副ドメイン長）（前列左から5番目）藤田様（長崎造船所所長、スチームパワー事業部長）（前列一番右）安田副センター長（前列一番左）、前川特任教授（元副社長）（前列左から２番目）、中野センター長（前列左から４番目）、後列右から、木村技術職員、趙准教授、桐原シグマクシス常務執行役員

【学会】中野研究室のメンバーが 2026 MRS Spring Meeting（@Honolulu, United States of America, 4月26日～5月1日）に参加しています。

2026-04-30T10:06:20Z

2026/04/27
〇Creation of Materials by Super-Thermal Field in Additive Manufacturing--From Digital-Twin Science to the Future of Non-Equilibrium Materials Design
Yuichiro Koizumi, Masayuki Okugawa, Yoshitaka Adachi, Kohei Morishita, Kazuhisa Sato, Yoshiaki Toda, Takuya Ishimoto, Teiichi Kimura, Takayoshi Nakano

Invited Speaker
〇Control of Crystallographic Textures and Macroscopic Shapes via Metal Additive Manufacturing
Takayoshi Nakano

2026/04/28
Invited Speaker
〇Creep Deformation Mechanism of LPBFed Near α, and Near β - Ti Alloys
Yoko Yamabe-Mitarai, Yoshiaki Toda, Tetsuya Matsunaga, Ryosuke Ozasa, Takuya Ishimoto, Tsutomu Ito, Takayoshi Nakano

〇Control of Microstructure and Functionality of Metastable Beta-Type Titanium Alloy Through Laser Powder Bed Fusion
Keitaro Miyasawa, Ryosuke Ozasa, Takayoshi Nakano

〇Microstructural Design of β-Phase Ti Alloys with Low Young's Modulus
Masakazu Tane, Takuya Ishimoto, Takayoshi Nakano

〇Guiding Osteogenic Differentiation of Mesenchymal Stromal Cells by Periodic Grooved Surfaces Fabricated via Metal Additive Manufacturing
Tadaaki Matsuzaka, Aira Matsugaki, Takayoshi Nakano

Invited Speaker
〇Microstructure Control of TiAl Alloys by Electron Beam Powder Bed Fusion
Hiroyuki Yasuda, Ken Cho, Masao Takeyama, Takayoshi Nakano

〇Strengthening of IN718 by the Artificial Introduction of Interfaces Between Differently Oriented Crystallographic Regions in L-PBF
Taichi Kikukawa, Takuya Ishimoto, Tsuyoshi Mayama, Takayoshi Nakano

〇Neutron Diffraction Study of Internal Residual Stress Distribution in Stainless Steel Fabricated by Laser Powder Bed Fusion
Ken Cho, Koki Tanaka, Takayoshi Nakano, Yuichiro Koizumi and Hiroyuki Yasuda

2026/04/29
〇APB Superelasticity in Fe3Al Single Crystals Fabricated by Laser Powder Bed Fusion
Yuheng Liu, Tsubasa Sato, Masayuki Okugawa, Kazuhisa Sato, Yoshitaka Adachi, Jerome Adrien, Eric Maire, Hiroyuki Yasuda, Takayoshi Nakano, Yuichiro Koizumi

集合写真（大阪大学小泉雄一郎先生（一番左）とともに）

【論文】Taylor & FrancisのTransactions of the IMFにバイオフィルムに関する論文が受理されました。

2026-04-30T01:45:18Z

Hideyuki Kanematsu*, Akiko Ogawa, Ryoichi Ichino, Takayoshi Nakano:
International Standards for Evaluating Antibacterial, Antiviral, and Antibiofilm Properties of Surface-Finished Materials: A Critical Review
Transactions of the IMF, (2026), in press.

DOI: https://doi.org/10.1080/00202967.2026.2668841

【論文】レーザー粉末床溶融法（L-PBF）の超急冷を用いて、結晶配向と高Sn含有準安定状態を実現したβ-Ti合金の機能性向上に関する論文がAdditive Manufacturing誌（IF＝11.1）にオープンアクセスとして掲載されました。

2026-04-29T22:21:00Z

Naoki Nohira*, Cheng Chen, Yilin Jin, Wan-Ting Chiu, Akira Umise, Takeshi Teramoto, Masaki Tahara*, Ryosuke Ozasa, Takuya Ishimoto, Yuichiro Koizumi, Takayoshi Nakano, Hideki Hosoda:
Introducing a novel fabrication route for metastable β-type Ti-Cr-Sn alloys with ultra-high Sn content using pure elemental mixed powders via laser powder bed fusion,
Additive Manufacturing, (2026), 124, 105213; 1-12.

DOI: https://doi.org/10.1016/j.addma.2026.105213

論文はこちら
PDFはこちら

Abstract
This study investigates the fabrication of ultra-high Sn-containing metastable β-type Ti-Cr-Sn alloys using Laser Powder Bed Fusion (L-PBF). By utilizing the rapid solidification inherent to L-PBF, retention of an ultra-high Sn metastable β phase at room temperature was achieved in compositions that are difficult to obtain via conventional processing routes. To address a key challenge in L-PBF, the high material cost associated with pre-alloyed powders, a mixture of pure elemental powders was employed as a cost-effective alternative feedstock. The effects of laser power on the microstructure, phase constitution, crystallographic texture, and mechanical properties of the as-built specimens were systematically evaluated. The results demonstrate that L-PBF successfully produced a homogeneous ultra-high Sn β solid solution while effectively suppressing the formation of ω phase and Ti₃Sn compounds. Under the highest laser power condition of 360 W, complete melting and the formation of a single β phase were achieved. The conventional unidirectional laser scanning strategy (X-scan), in which the scanning direction is kept constant between layers, resulted in <110>_β alignment along the build direction and <100>_β alignment along the scan direction. The specimen fabricated at 360 W exhibited the most homogeneous microstructure, together with appropriate strength, excellent ductility, and low Young's modulus. These findings demonstrate the feasibility of low-cost processing via L-PBF while achieving enhanced functional performance in high-Sn metastable β-Ti alloys.

keywords: Additive manufacturing; β-Ti alloys; Laser powder bed fusion; Metastable; Ti-Cr-Sn

【招待講演】中野先生が2026 MRS Spring Meetingで招待講演をしました。

2026-04-26T02:31:25Z

Takayoshi Nakano:
Control of crystallographic textures and macroscopic shapes via metal additive manufacturing,
Creation of Materials by Super-Thermal Field in Additive Manufacturing--From Digital-Twin Science to the Future of Non-Equilibrium Materials Design,
2026 MRS Spring Meeting,
Honolulu, 27th April 2026, 1:45pm - 2:15pm, Makiki Room (2F), Prince Wikiki

招待講演の様子

【論文】Materials Transactionsに、電子ビーム積層造形法で作製した純チタン表面上のNiTiコーティングにおいて、熱処理による組織の均質化と耐摩耗性の向上を示した論文が掲載されました。

2026-04-25T03:13:52Z

Lei Wang, Masayuki Okugawa*, Yuheng Liu, Ken Cho, Yuichiro Koizumi*, Hiroyuki Y. Yasuda and Takayoshi Nakano:
Microstructural Evolution and Wear Resistance Enhancement of Electron-Beam-Fabricated Nickel Titanium Coatings on Titanium by Heat Treatment,
Materials Transactions, 67 (2026) 771-782.

DOI: https://doi.org/10.2320/matertrans.MT-M2025170

論文はこちら
PDFはこちら

Abstract
We previously proposed a novel method for fabricating NiTi coatings on pure Ti surfaces using electron-beam multi-track scanning to improve wear resistance. However, electron-beam scanning coatings exhibit spatial inhomogeneity in phase and elemental distributions, which is suggested to decrease wear resistance. In the present study, we investigated the effects of heat treatment on reducing inhomogeneity and improving the performance of the coatings. As a result, the homogeneity of the electron beam (EB) scanned coatings was significantly enhanced after annealing (900°C, 10 min), and then the Ni₄Ti₃ phase precipitated in the annealed EB-scanned coatings after aging (400°C, 60 min). The results of nanoindentation show that the hardness/indentation modulus (H/E) ratio and depth recovery ratio (η_d,h) of the Ti-rich EB-scanned coatings increased by 27% and 21%, respectively, after annealing and aging. The H/E ratio and η_d,h of the Ni-rich EB-scanned coating improved by 8% and 14%, respectively, after annealing and aging. The wear test results demonstrate that the wear rates of the two coatings decreased by 52% and 26% after annealing and aging, respectively, approaching the wear performance of bulk Nitinol.

keywords: commercially pure titanium; nickel titanium coating; heat treatment; mechanical properties; wear resistance

【AM委員会】中野先生が委員長を務めた、経済産業省での金属ＡＭの普及拡大・活用促進に向けた検討会報告書が公開されました。

2026-04-24T07:37:39Z

【公開先URL】
https://www.meti.go.jp/policy/mono_info_service/mono/sokeizai/AM-WG.html

★報告書＜概要版＞はこちら

★報告書はこちら

★参考資料集はこちら

【行事】中野研究室の新B4歓迎会が行われました。

2026-04-17T11:44:34Z

本日、新B4の歓迎会が行われました。新しく配属されたB4は、奥村君、角田君、木村さん、佐々木君、社領君、疊開君、中村君、原田君、細谷君の9名です。
スタッフ、学生全員で頑張っていきましょう！！

集合写真