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Latest 30 articles

2025.09.17

【学会】日本金属学会2025年（第177回）春期講演大会（@北海道大学、9月17日～9月19日）に参加しています。

中野研究室のメンバーで集合写真を撮影しました。
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2025.09.12

2025年9月12日【報道】9月11日の産総研・中部大学・大阪大学・名古屋工業大学からのプレスリリースを受けて、多数の報道がなされました。

9月11日の産総研・中部大学・大阪大学・名古屋工業大学からのプレスリリースを受けて、多数の報道がなされました。

★日刊工業新聞
★Ｎｅｗｓウェーブ２１
★共同通信
★下野新聞
★沖縄タイムス+
★北海道新聞デジタル
★秋田魁新報社
★FM FUKUOKA
★山梨日日新聞デジタル

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2025.09.11

2025年9月11日【プレスリリース】Advanced Healthcare Materialsの研究論文掲載に関して、産総研・中部大・大阪大・名古屋工業大からプレスリリースがされました。

Sungho Lee*, Hayato Asano, Makoto Sakurai, Takayoshi Nakano, and Toshihiro Kasuga:
Preparation of Bifunctional Orthosilicophosphate MgO-CaO-ZnO-P₂O₅-SiO₂ Glasses: in vitro Evaluation of Antibacterial Activity and Osteoblast Gene Expression Behavior, Advanced Healthcare Materials, (2025), e02546; 1-11.

DOI: https://doi.org/10.1002/adhm.202502546

プレスリリースはこちら

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2025.09.09

【行事】毎年恒例の研究室旅行を行い大いに盛り上がりました。

9月8日、9日は中野研究室の毎年恒例行事である研究室旅行を実施しました。
今年はM1の学生が中心となって計画してくれ、観光やレクリエーションを通じて大いに盛り上がりました。

image0.jpeg城崎温泉にて

image0.jpeg天橋立にて

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2025.09.06

【論文】Advanced Healthcare Materialsに、リン酸塩系バイオガラスの抗菌性と骨芽細胞応答に関する研究論文がOA論文として掲載されました。

Sungho Lee*, Hayato Asano, Makoto Sakurai, Takayoshi Nakano, and Toshihiro Kasuga:
Preparation of Bifunctional Orthosilicophosphate MgO-CaO-ZnO-P₂O₅-SiO₂ Glasses: in vitro Evaluation of Antibacterial Activity and Osteoblast Gene Expression Behavior, Advanced Healthcare Materials, (2025), article number e02546.

DOI: https://doi.org/10.1002/adhm.202502546

論文はこちら
PDFはこちら

Abstract
Phosphate and phosphate invert glasses contain various elements, with a wide range of compositions. Recently, our group reported orthosilicophosphate glasses (SPGs) and the glass network structure composed of orthophosphates and orthosilicates crosslinked by cations. ZnO is an intermediate oxide that improves the chemical durability of glass. Additionally, Zn2+ ions exhibit antibacterial activity and stimulate bone formation. In this work, ZnO-containing SPGs are prepared for biomedical applications. The glasses are mainly composed of PO4, SiO4, MgO4, and ZnO4 orthotetrahedral structures. The ZnO-containing SPGs exhibit excellent antibacterial activity, with bacterial counts > 5 orders of magnitude lower than that of the control. Meanwhile, ZnO-containing SPGs have mild inhibitory effects on cell proliferation by Zn2+ ions; however, they exhibit significant upregulation of osteogenic markers compared with the control owing to the release of inorganic ions from the glasses. The ZnO-containing SPGs prepared in this work exhibit bifunctional properties suitable for biomedical applications. They serve as bioadaptive materials capable of controlling gene expression by releasing therapeutic ions.

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2025.09.05

2025.9.5　第67回歯科基礎医学会学術大会で講演を行いました。

日本学術会議シンポジウム（市民公開講座）「マテリアルとライフの融合サイエンス」
「骨質再建のための材料表面/生物相界面反応理解とその人為的制御」
松垣 あいら、 中野 貴由 北九州国際会議場　A会場（メインホール）

IMG_0437 (002).jpg歯科基礎＿１_page-0001.jpg歯科基礎＿２_page-0001.jpg

写真：オーガナイザーの塙隆夫先生、松本卓也先生、樋田京子先生、石丸直澄先生、大矢根綾子先生とともに。

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2025.09.01

2025年9月1日　【解説・論文】中野先生が特集したスマートプロセス学会誌「AM技術の進展と応用（Ⅱ）」が発行され、中野研関係の解説と論文が掲載されました。

中野先生が特集したスマートプロセス学会誌「AM技術の進展と応用（Ⅱ）」が発行され、中野研関係の解説と論文が掲載されました。
Vol. 14[No. 5]、2025（令和 7 年 9 月）、AM技術の進展と応用（Ⅱ）、スマートプロセス学会誌
【解説】
★桐原聡秀、中野貴由：巻頭「AM技術の進展と応用（Ⅱ）」、 スマートプロセス学会誌、14[5], (2025), pp.199. ★小泉雄一郎、奥川将行、柳玉恒、中野貴由：新材料創製のための粉末床溶融結合式付加製造のデジタルツイン科学、 スマートプロセス学会誌、14[5], (2025), pp.200-207.
★石本卓也、中野貴由：金属AMによる異方性機能設計―形状と結晶配向の重畳、 スマートプロセス学会誌、14[5], (2025), pp.221-226.
★小笹良輔、Gokcekaya Ozkan、中野貴由：レーザ粉末床溶融結合によるBCC型ハイエントロピー合金のin-situ合金化、 スマートプロセス学会誌、14[5], (2025), pp.243-248.
【研究論文】
★松坂匡晃、小坂朋生、山野大陸、船奥和真、劉甜、松垣あいら、中野貴由：生体用AMインプラント材料の抗菌特性評価のためのin vitro 共培養モデルの構築、 スマートプロセス学会誌、14[5], (2025), pp.249-252.
★小笹良輔、Kim Yong Seong、朝倉光平、堀尾尚平、鰐渕良祐、中野貴由：金属3Dプリンタ用レーザ照射による非等量Ti-Nb-Mo-Ta-W系ハイエントロピー合金の組織形成挙動、 スマートプロセス学会誌、14[5], (2025), pp.253-257.
★宮澤啓太郎、小笹良輔、内芝旭祥、清水佑太、中野貴由：L-PBF で造形した準安定β型Ti合金におけるヤング率の変化、 スマートプロセス学会誌、14[5], (2025), pp.258-263.

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2025.08.22

【論文】産総研や名工大との共同研究によるバイオガラスによるZnの徐放による骨質の向上に関する研究成果がAdvanced Healthcare Materialsに受理されました。9月9日に出版される予定です。

Sungho Lee*, Hayato Asano, Makoto Sakurai, Takayoshi Nakano, and Toshihiro Kasuga:
Preparation of Bifunctional Orthosilicophosphate MgO-CaO-ZnO-P₂O₅-SiO₂ Glasses: in vitro Evaluation of Antibacterial Activity and Osteoblast Gene Expression Behavior,
Advanced Healthcare Materials, (2025), in press.

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2025.08.06

【論文】Materials Today CommunicationsにTi合金の酸化抑制に関する中国東北大との共同研究論文が掲載されました。

Yiming Jin, Jiani Li, Takayoshi Nakano, Hideki Hosoda, Mitsuo Niinomi, Xiaowei Zhang, Deliang Zhang, Xiaoli Zhao*:
Zr-Enhanced Ambient-Air Thermal Oxidation of Ti-30Zr-5Mo Alloy Using Low Tβ for Implants, Materials Today Communications, (2025), Volume 48, 113442.

DOI: https://doi.org/10.1016/j.mtcomm.2025.113442

論文はこちら
PDFはこちら

Abstract
Metastable β-Ti alloy Ti-30Zr-5Mo (Tβ ≈ 700 °C) offers low modulus, biocompatibility, and strength for spinal rod implants but has limited hardness (280 Hv) and wear resistance. Conventional surface treatments like vacuum-based physical vapor deposition (PVD), are costly and complex. This study exploits the low Tβ and high Zr content (30 wt.%) of Ti-30Zr-5Mo alloy for single-step, ambient-air thermal oxidation at 600-700 °C, combining heat treatment with surface modification. The low Tβ ensures controlled oxidation, preventing over-oxidation, while Zr's selective oxidation forms a dense ZrO2-rich layer, which is harder than TiO2, enhancing surface hardness. Spontaneous tetragonal to monoclinic phase transitions in ZrO2 further improve toughness. The resulting 5 μm-thick oxide layers exhibit a threefold hardness increase (904 Hv vs. 280 Hv), a surface roughness of 0.30 μm (suitable for osseointegration), strong interfacial adhesion (critical load: 43 N), and an 18-fold reduction in corrosion current density (from 1.62×10-7 to 8.96×10-9 A·cm-2). Despite minor microcracks, the layers maintain structural integrity, offering exceptional durability. This atmosphere-free approach provides a scalable solution for orthopedic and dental implants, combining mechanical durability with biological integration. The insights into Zr-driven oxidation dynamics at low Tβ could inform vacuum-based processes, when controlled oxygen partial pressure might further optimize oxide layer properties, aligning with advancement in surface technology.

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2025.08.01

2025年8月【解説】日本Additive Manufacturing学会誌のAMフュチャー「AMプロジェクト」（Vol. 1[No. 2]、2025（令和7年8月））が発行され、中野研関連解説が発行されました。

【解説】
日本Additive Manufacturing学会誌のAMフュチャー「AMプロジェクト」（Vol. 1[No. 2]、2025（令和7年8月））が発行され、中野研関連解説が発行されました。
Vol. 1[No. 2]、2025（令和7年8月）、AMフュチャー
★中野貴由、阿部英司、眞山剛、石本卓也：CREST ナノ力学―金属3Dプリンティングによるカスタム力学機能制御、 AMフュチャー、1[2]、(2025)、pp.191-194.
★小泉雄一郎、足立吉隆、森下浩平、佐藤和久、戸田佳明、石本卓也、木村禎一、中野貴由：超温度場材料創成学―AMを中心とした巨大ポテンシャル勾配による新材料創製、 AMフュチャー、1[2]、(2025)、pp.195-198. ★森浩亮、金孝鎮、中野貴由：炭素循環社会に貢献する金属AM触媒、 AMフュチャー、1[2]、(2025)、pp.219-222.

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2025.07.29

【論文】Materials Today CommunicationsにTi合金の酸化抑制に関する中国東北大との共同研究論文が出版されました。

Yiming Jin, Jiani Li, Takayoshi Nakano, Hideki Hosoda, Mitsuo Niinomi, Xiaowei Zhang, Deliang Zhang, Xiaoli Zhao*:
Zr-Enhanced Ambient-Air Thermal Oxidation of Ti-30Zr-5Mo Alloy Using Low Tβ for Implants, Materials Today Communications, (2025), 113442.

DOI: https://doi.org/10.1016/j.mtcomm.2025.113442

論文はこちら

Abstract
Metastable β-Ti alloy Ti-30Zr-5Mo (Tβ ≈ 700 °C) offers low modulus, biocompatibility, and strength for spinal rod implants but has limited hardness (280 Hv) and wear resistance. Conventional surface treatments like vacuum-based physical vapor deposition (PVD), are costly and complex. This study exploits the low Tβ and high Zr content (30 wt.%) of Ti-30Zr-5Mo alloy for single-step, ambient-air thermal oxidation at 600-700 °C, combining heat treatment with surface modification. The low Tβ ensures controlled oxidation, preventing over-oxidation, while Zr's selective oxidation forms a dense ZrO2-rich layer, which is harder than TiO2, enhancing surface hardness. Spontaneous tetragonal to monoclinic phase transitions in ZrO2 further improve toughness. The resulting 5 μm-thick oxide layers exhibit a threefold hardness increase (904 Hv vs. 280 Hv), a surface roughness of 0.30 μm (suitable for osseointegration), strong interfacial adhesion (critical load: 43 N), and an 18-fold reduction in corrosion current density (from 1.62×10-7 to 8.96×10-9 A·cm-2). Despite minor microcracks, the layers maintain structural integrity, offering exceptional durability. This atmosphere-free approach provides a scalable solution for orthopedic and dental implants, combining mechanical durability with biological integration. The insights into Zr-driven oxidation dynamics at low Tβ could inform vacuum-based processes, when controlled oxygen partial pressure might further optimize oxide layer properties, aligning with advancement in surface technology.

Keywords
Ti-30Zr-5Mo alloy; Thermal oxidation; Oxidation mechanism; Internal oxidation; Surface modification

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2025.07.28

【論文】Materials Today CommunicationsにTi合金の酸化抑制に関する中国東北大との共同研究論文が受理されました。

Yiming Jin, Jiani Li, Takayoshi Nakano, Hideki Hosoda, Mitsuo Niinomi, Xiaowei Zhang, Deliang Zhang, Xiaoli Zhao*:
Zr-Enhanced Ambient-Air Thermal Oxidation of Ti-30Zr-5Mo Alloy Using Low Tβ for Implants, Materials Today Communications, (2025), in press

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2025.07.02

【論文】バイオフィルムに関する研究が、Transactions of the IMF (YTIM)にOA論文として掲載されました。

Hideyuki Kanematsu*, Shochiku Kure, Risa Kawai, Hidekazu Miura, Takayoshi Nakano:
Antibiofilm Potential of Graphene-Dispersed Alkoxysilane Coatings:
A Materials Science Perspective, Transactions of the IMF (YTIM),
The International Journal of Surface Engineering and Coatings, (2025).
DOI: https://doi.org/10.1080/00202967.2025.2520667

論文はこちら
PDFはこちら

Abstract
This study investigates the antibiofilm properties of alkoxysilane-based coatings incorporating dispersed multilayer graphene powder. Graphene, synthesised via a proprietary method, was incorporated into a resin matrix at various concentrations (0.1%, 0.5%, and 1.0% by weight) and applied to glass substrates. Raman spectroscopy confirmed the presence of defect-rich, multilayer graphene, which is known to enhance antimicrobial surface properties. Biofilm formation by Staphylococcus epidermidis was evaluated using ISO 4768-standardised crystal violet staining. Results indicated that biofilm development was effectively suppressed at concentrations up to 0.5%, whereas an unexpected increase was observed at 1.0%, possibly due to graphene aggregation and reduced surface exposure. The findings suggest that both graphene concentration and dispersion quality critically influence antibiofilm efficacy. The study highlights the dual role of graphene, both as a physical and chemical antibacterial agent, and its potential application in medical, industrial, and hygienic materials. Further investigation is warranted to optimise dispersion and explore microbial-material interactions in real-world conditions.

Keywords
Graphene-dispersed coatings; alkosysilane resin; biofilm suppression; crystal violet assay; Raman spectroscopy





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2025.07.01

2025年7月1日【解説・論文】中野先生が特集したスマートプロセス学会誌「AM技術の進展と応用（Ⅰ）」が発行され、中野研関係の解説と論文が掲載されました。

中野先生が特集したスマートプロセス学会誌「AM技術の進展と応用（Ⅰ）」が発行され、中野研関係の解説と論文が掲載されました。
Vol. 14[No. 4]、2025（令和7年7月）、AM技術の進展と応用（Ⅰ）、スマートプロセス学会誌
【解説】
★中野貴由、桐原聡秀：巻頭「AM技術の進展と応用（Ⅰ）」、 スマートプロセス学会誌、14[4], (2025), pp.123. ★安田弘行、趙研、竹山雅夫、中野貴由：航空機エンジン用TiAlタービンブレードのAM、 スマートプロセス学会誌、14[4], (2025), pp.175-180.
★森浩亮、金孝鎮、中野貴由、山下弘巳：AM 触媒反応管開発の最前線、 スマートプロセス学会誌、14[4], (2025), pp.181-186.
【研究論文】
★熊谷祥希、髙橋茉莉、小柳禎彦、小笹良輔、中野貴由：レーザ粉末床溶融結合法の造形過程におけるFe基合金の変形挙動に及ぼすマルテンサイト変態の影響、 スマートプロセス学会誌、14[4], (2025), pp.192-197.

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2025.06.30

【学会】中野研究室のメンバーが THERMEC2025（@University of Tours, France, 6月30日～7月4日）に参加します。

2025/6/30
Invited Speaker
〇Design of high entropy alloy with suppressed elemental segregation for laser powder bed fusion process
Ozkan Gokcekaya, Yong Seong Kim, Takayoshi Nakano

Invited Speaker
〇Electron Microscopy Studies on Orientation-Controlled 316L Austenitic Stainless Steel
Produced by Laser Powder Bed Fusion
Kazuhisa Sato, Shunya Takagi, Satoshi Ichikawa, Takuya Ishimoto, Takayoshi Nakano 

2025/7/1
Keynote Speaker
〇Innovative design of crystallographic textures and macroscopic shapes via metal additive manufacturing
Takayoshi Nakano

Poster presentation
〇Unique Hierarchical Structural Features Introduced by Laser Powder Bed Fusion and Their Contribution to Mechanical Function in IN718
Taichi Kikukawa, Takuya Ishimoto, Tsuyoshi Mayama, Ryosuke Ozasa, Takayoshi Nakano

Poster presentation
〇Microstructural Control of Unstable Beta-Type Titanium Alloy Through Powder Bed Fusion Using a Laser-Beam of Metals
Keitaro Miyasawa, Ryosuke Ozasa, Daisuke Egusa, Eiji Abe, Masakazu Tane, Takayoshi Nakano

Invited Speaker
〇Elastic properties of laser powder bed fusion processed β-phase Ti alloys  
Masakazu Tane, Shota Higashino, Eisuke Miyoshi, Takuya Ishimoto, Takayoshi Nakano   

Invited Speaker
〇Microstructure control of TiAl alloys using peculiar thermal history of additive manufacturing  
Ken Cho, Hiroyuki Y. Yasuda, Masao Takeyama, Takayoshi Nakano 

〇Novel cellular structure with phase-separation induced dislocation-network in Ti-Zr-Nb-Ta-Zr high entropy alloy fabricated by laser powder bed fusion  
Daisuke Egusa, Han Chen, Ryosuke Ozasa, Masayuki Okugawa, Taisuke Sasaki, Takuya Ishimoto, Koizumi Yuichiro, Takayashi Nakano, Eiji Abe  

Poster presentation
〇Spinodal Decomposition and Magnetic Properties of Single-Crystal-Like Fe-Cr-Co Alloy Fabricated by Laser-Powder Bed Fusion Type Additive Manufacturing 
Takato Saito, Yuheng Liu, Masayuki Okugawa, Kazuhisa Sato, Takayoshi Nakano, Yuichiro Koizumi 

2025/7/2
Invited Speaker
〇A Novel Strategy for the Control of Crystallographic Texture of Metals with Non-Cubic Crystal System via Powder Bed Fusion using a Laser-Beam of Metals
Ryosuke Ozasa, Koji Hagihara, Takayoshi Nakano

〇Discovery of nano-scaled promising strengthening factor in 316L stainless steel fabricated by laser 
powder bed fusion
Fei Sun, Yoshitaka Adachi, Kazuhisa Sato, Takuya Ishimoto, Takayoshi Nakano, Yuichiro Koizumi 

〇Nano-scaled solidification microstructure characteristics in additively manufactured 316L stainless steel  
Fei Sun, Yoshitaka Adachi, Kazuhisa Sato, Takuya Ishimoto, Takayoshi Nakano, Yuichiro Koizumi   

〇Influence of hierarchical structure on mechanical properties of additive manufactured IN718 alloys 
Kippei Yamashita, Ken Cho, Hiroyuki Y. Yasuda, Takuma Saito, Taisuke Sasaki, Sawaizumi Katsuhiko, Masayuki Okugawa, Koizumi Yuichiro, Takayoshi Nakano 

Invited Speaker
〇Growth of Antiphase Domain in Laser-Irradiated Region and Superelasticity of Single-Crystal Like Fe3Al Fabricated by Laser Powder Bed Fusion Process  
Yuheng Liu, Tsubasa Sato, Masayuki Okugawa, Kazuhisa Sato, Hiroyuki Y. Yasuda, Takayoshi Nakano, Yuichiro Koizumi  

2025/7/3
Invited Speaker
〇Additive Manufacturing of Cell-Based 3D Bone-Mimetic Collagen/Apatite Structures
Aira Matsugaki, Takayoshi Nakano

Invited Speaker
〇Control of Bone Microstructure Formation: Role of Soluble Proteins Secreted by Osteocytes
Tadaaki Matsuzaka, Aira Matsugaki, Takayoshi Nakano

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2025.06.13

An international collaborative research project with Postec on a high-strength, high-ductility medium-high entropy alloy utilizing the competition between precipitation and lattice strain has been published in "Materials Science and Engineering A".

Jae Heung Lee, Hyeonseok Kwon*, Gang Hee Gu, Ji Yeong Lee, Sang Guk Jeong, Emad Maawad, Changwan Ha, Jaemin Wang, Byeong-Joo Lee, Sangbong Yi*, Takayoshi Nakano, Hyoung Seop Kim*:
Harnessing competitive interplay between precipitation and lattice distortion for strong and ductile medium-entropy alloy,
Materials Science and Engineering A, 942, (2025) 148642: 1-11.
DOI: https://doi.org/10.1016/j.msea.2025.148642

Click here for this paper.

Abstract
In Co-Cr-Fe-Ni-Mo-C ferrous medium-entropy alloys (FeMEAs), precipitation-driven alteration of matrix composition affects both the kinetics of deformation-induced martensitic transformation (DIMT) and the degree of lattice distortion. While DIMT has been well studied, the role of lattice distortion remains explored. In this study, we simultaneously enhance the strength and ductility in Co18Cr13Fe57.5Ni7.5Mo3C1 (at%) FeMEA by harnessing the competitive interplay between precipitation and lattice distortion. Two annealed samples with similar grain sizes but different precipitate characteristics were prepared. The sample with suppressed precipitation exhibits improved ductility while maintaining comparable strength. The two specimens exhibited similar yield strengths due to a trade-off between precipitation strengthening and solid solution strengthening. However, the sample with higher lattice distortion and reduced precipitation demonstrates superior strain-hardening behavior owing to the lattice distortion-induced back stress, acting as an effective strain-hardening mechanism, and delayed DIMT, serving as a ductilizing mechanism. This work offers a strategy to modulate strengthening and deformation mechanisms in Co-Cr-Fe-Ni-Mo-C FeMEAs via precipitation control.

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2025.04.10

Research on improving the creep properties of Ti alloys has been published in Journal of Metallurgical and Materials Transactions A.

Prince Valentine Cobbinah*, Sae Matsunaga, Yoshiaki Toda, Ryosuke Ozasa, Takuya Ishimoto, Takayoshi Nakano, Tsutomu Ito, Yoko Yamabe-Mitarai:*
On the enhanced creep performance in Ti6246 achieved through Laser Powder Bed Fusion (LPBF) processing,
Metallurgical and Materials Transactions A, (2025), in press.
DOI: https://doi.org/10.1007/s11661-025-07759-8

Click here for this paper.

Abstract
The high susceptibility of the Ti-6Al-2Sn-4Zr-6Mo wt pct (Ti6246) alloy to microstructural changes stands as a challenge when processed by the laser powder bed fusion (LPBF) technology. However, leveraging the capabilities of the LPBF process to successfully control the microstructure (and/or crystallographic texture) of the Ti6246 could improve mechanical properties, particularly at elevated temperatures. In this study, the creep performance (at 500 °C) of Ti6246 fabricated from three different LPBF processing conditions and heat-treated (HT) at 885 °C were investigated. In the as-built state, all the LPBFed-Ti6246 exhibited columnar microstructures with crystallographic lamellar-like microstructure (CLM), a near-single crystal-like microstructure (SCM), and polycrystalline microstructure (PCM) textures, respectively. At low applied stresses (100-300 MPa), diffusional creep was the dominant deformation mechanism and its resistance depended on grain size. The reference β-forged-HT Ti6246, characterized by large equiaxed grains, exhibited the lowest strain rate compared to the columnar microstructure of SX1 (CLM)-HT, SX2 (SCM)-HT, and SX3 (PCM)-HT. Conversely, dislocation slip governed deformation at high applied stresses (400-580 MPa) and its efficacy depended on the α/β interfaces in the microstructures. Disjointed columnar grains in SX1 (CLM)-HT and the deformation of the polycrystalline grains in SX3 (PCM)-HT indicated that the melt pool boundaries were unstable in the LPBFed-Ti6246. SX2 (SCM)-HT exhibited the longest creep life due to the relatively stable melt pool boundaries and the near < 001 > SCM crystallographic texture parallel to the applied stresses. Shallow ductile dimples and tears and the observation of laser scan tracks characterized the fracture surfaces of the LPBFed-Ti6246. These indicated that failure occurred by intergranular ductile fracture resulting from the formation of microvoids at the melt pool boundaries.

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2025.03.18

Research on computer simulation of AM has been published in Journal of the Japan Society of Powder and Powder Metallurgy.

Shuhei Mino, Masayuki Okugawa, Takayoshi Nakano, Yuichiro Koizumi:
Raking and Fusing Behaviors during Fabrication of Multiple-layers in Powder Bed Fusion: An integrated discrete Element and computational thermal fluid Dynamics Study
Journal of the Japan Society of Powder and Powder Metallurgy, 72, (2025), 16P-T6-11; S1465-S1469.
https://doi.org/10.2497/jjspm.16P-T6-11

Click here for this paper.

Abstract
In the powder bed fusion (PBF) type additive manufacturing (AM), understanding the relationship between the quality of the powder bed and the powder spreading process is crucial to avoiding defect formation. In this study, we investigated the powder-raking behavior during the multiple-layer fabrication process by discrete element method (DEM) and computational thermal-fluid dynamics (CtFD) simulations. The integrated PBF process simulation revealed that the gap height between the powder spreading blade and the build platform increases nonlinearly with the number of stacking layers, and accordingly, the powder-covered area ratio increases in the formed powder beds and affects the melt pool shapes. The powder raking behavior and melting and solidification behavior are related to each other, and both the powder raking and the irradiation conditions need to be optimized to obtain a high-quality part in the PBF process.

Keywords
additive manufacturing; powder bed fusion; discrete element method; computational thermal-fluid dynamics

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2025.03.15

A paper on Young's modulus prediction for Ti alloys was published as an OA article in Additive Manufacturing (IF=10.3).

Shota Higashino, Daisuke Miyashita , Takuya Ishimoto, Eisuke Miyoshi, Takayoshi Nakano, Masakazu Tane*:
Low Young's modulus in laser powder bed fusion processed Ti-15Mo-5Zr-3Al alloys achieved by the control of crystallographic texture combined with the retention of low-stability bcc structure,
Additive Manufacturing, 102 (2025), 104720; 1-13.
https://doi.org/10.1016/j.addma.2025.104720

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Abstract
Metastable β (body-centered cubic)-phase Ti alloys, quenched from a high-temperature β-phase field, have attracted great interest as biomedical implants, owing to their low Young's modulus. Recently, the application of additive manufacturing (AM) to β-phase Ti alloys has gathered much attention, because the AM process can form anisotropic crystallographic texture in which an elastically soft direction is preferentially oriented, resulting in low Young's modulus in a specific direction. However, the effects of anisotropic texture and microstructure formed by the AM process on anisotropic elastic properties have not been clarified in detail. In the present study, we measured all the independent elastic stiffness components of β-phase Ti-15Mo-5Zr-3Al (mass%) alloys, prepared by bidirectional scanning with (XY-scan) and without (X-scan) an interlayer rotation of 90° in laser powder bed fusion (LPBF), one of the AM processes, using resonant ultrasound spectroscopy. The measurements revealed that the LPBF-processed Ti alloys exhibited strong elastic anisotropy and a low Young's modulus (below 60 GPa) in the <100>-oriented direction of the alloy prepared by the XY-scan. Furthermore, micromechanics calculations based on Eshelby's inclusion theory revealed that the single crystal constituting the alloys prepared by LPBF had almost the same elastic stiffness as that of a single crystal prepared by the floating zone melting, which indicated that the metastable β phase was retained by suppressing an easily occurring β- to ω-phase transformation during LPBF. These results indicate that texture control combined with retention of the metastable β phase by LPBF achieves biocompatible low Young's modulus.

Keywords
Laser powder bed fusion; Elastic properties; Titanium alloys; Crystallographic texture; ω phase transformation

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2025.03.15

The one-process realization of alloying, microstructure control, and shape control by metal 3D printers was published in Materials & Design.

Yong Seong Kim, Ozkan Gokcekaya*, Kazuhisa Sato, Ryosuke Ozasa, Aira Matsugaki, Takayoshi Nakano*:
In-situ alloying of nonequiatomic TiNbMoTaW refractory bio-high entropy alloy via laser powder bed fusion: Achieving suppressed microsegregation and texture formation,
Materials & Design, 252, (2025), 113824; 1-18.
https://doi.org/10.1016/j.matdes.2025.113824

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Abstract
High-entropy alloys (HEAs) have attracted considerable attention owing to their excellent properties. However, the severe segregation of the constituent elements remains a common challenge in refractory HEAs. Recently, an approach to suppress segregation was proposed using laser powder bed fusion (LPBF) owing to the ultra-high cooling rates during solidification. Despite the advantages of LPBF, the persistent microsegregation between the dendritic and interdendritic regions of refractory HEAs and costly gas atomization process hinder the further development. To address these challenges, a novel nonequiatomic TiNbMoTaW refractory HEA was designed to minimize the difference between the liquidus and solidus temperatures to prevent segregation and phase separation for a better biological performance. In-situ alloying was implemented instead of costly and time-consuming gas atomization process. The segregation of constituent elements was suppressed by remelting, resulted in epitaxial growth and development of crystallographic texture, consequently reducing residual stress. The mechanical properties were improved due to the increase of solid solution strengthening and densification. It showed superior mechanical strength and equivalent biocompatibility compared to conventional biomaterials, indicating its superiority as a biomaterial. This study represents the first successful control of crystallographic texture through in-situ alloying of BioHEAs for next-generation biomaterials.

Keywords
High entropy alloys; Additive manufacturing; In-situ alloying; Crystallographic texture; Segregation

 

 

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2025.03.14

The results of joint research on AM with Abe Lab. at the University of Tokyo were published in Additive Manufacturing (IF=10.3).

Han Chen, Daisuke Egusa*, Zehao Li, Taisuke Sasaki, Ryosuke Ozasa , Takuya Ishimoto, Masayuki Okugawa, Yuichiro Koizumi, Takayoshi Nakano, Eiji Abe*
Phase-separation induced dislocation-network cellular structures in Ti-Zr-Nb-Mo-Ta high-entropy alloy processed by laser powder bed fusion,
Additive manufacturing, 102, (2025), 104737; 1-14.
https://doi.org/10.1016/j.addma.2025.104737

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Abstract
Hierarchical structures, such as cellular structures, elemental segregations, and dislocation-network, are often proposed to enhance the mechanical properties of high-entropy alloys (HEAs) fabricated via additive manufacturing (AM). The formation of cellular structures is often attributed to elemental segregation during the solidification process or thermal strain resulting from the AM process. Here, we present a novel cellular structure where phase-separation and dislocation-network coupled in Ti-Zr-Nb-Mo-Ta HEA processed by laser powder bed fusion (L-PBF). Electron microscopy observations and X-ray diffraction (XRD) analyses show that this unique cellular structure consists of Zr-rich and Ta-rich body-center cubic (BCC) phases as the cell-wall and the cell-core, respectively, with their lattice constant difference of about 1 %. Moreover, a higher density of dislocations forming distinct networks is detected within this cellular structure, whose density reached 8 × 10 14 m 2 . Ma chine learning analysis reveals that the dislocations preferentially occur on the Zr-rich BCC side, thus accom modating the strains significant around the boundaries between the two BCC phases. With the aid of thermodynamic simulations, we propose a formation mechanism of the present cellular structure, which is governed by the elemental partitioning behavior of Zr and Ta during a solid-state phase separation under rapid cooling. Boundaries with this phase separation are introduced as semi-coherent interfaces with misfit disloca tions, introducing a high-density dislocation in the present material. This novel cellular structure can signifi cantly enhance the strength of AM HEAs, providing valuable insights for developing high-performance AM metals through the design of hierarchical microstructures.

Keywords
High-entropy alloy; Laser powder bed fusion; Cellular structure; Phase separation; Dislocation-network; Electron microscopy; Machine learning

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2025.03.13

The Signature Pavilion "Future of Life" website has been renewed and reopened, and an article about Nakano Lab. has been posted on the "Future Technology" Seeds page.

An Innovative Bone Medical Device That Can Induce Strong Bones from the Early Stages of Regeneration

Click here to go to the top page→
https://expo2025future-of-life.com/
Click here to go to the Seeds of Future Technology top page→
https://expo2025future-of-life.com/about/future-technology-seeds/

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2025.02.01

A paper on the microstructural effects of post-processing during laser and electron beam lithography has been published in the CIRP Journal of Manufacturing Science and Technology (IF=4.6).

Jibin Boban*, Afzaal Ahmed, Ozkan Gokcekaya , Takayoshi Nakano:
Ultra-precision surface treatment of beta-Titanium alloy printed using laser and electron beam melting sources, CIRP Journal of Manufacturing Science and Technology, 58, (2025), 01.006; 1-19.
https://doi.org/10.1016/j.cirpj.2025.01.006

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Abstract
Additive Manufacturing (AM) is a near net shape fabrication technology offering exceptional design freedom for complex part production. However, the inadequate surface quality and poorly generated micro-features adversely affect the functional performance of metal AM parts thereby restricting the direct adoption in biomedical implantation applications. Ultra-precision diamond turning (UPDT) can be regarded as a possible solution to overcome the aforementioned challenges in metal AM. However, the machinability of metal AM parts at ultra-precision level is highly sensitive to the material specific attributes and microstructure generated by the thermal characteristics of the process. In light of this, the present study follows a novel direction by investigating the dependence of distinct material characteristics imparted by two different AM powder melting sources on the ultra-precision post-treatment performance. Experiments were conducted on laser and electron beam printed beta-Ti alloy (Ti-15Mo-5Zr-3Al) which has potential importance in biomedical applications. The results demonstrate that the microstructural variations in respective samples affect the process performance and final surface integrity. The samples printed using laser powder bed fusion (LPBF) achieved a final surface finish (Sa) of ~66.3 nm after UPDT relative to the electron beam powder bed fusion (EPBF) samples (~104.3 nm). The cutting forces tends to exhibit sharp dip in forces in case of LPBF samples when micro-cutting was done perpendicular to the beam scanning direction. The chip morphology analysis corresponding to the LPBF and EPBF samples sub stantiates the generation of chips with segmentation/serrations on the free chip surface and parent material adhesion on the tool-chip contact surface. Further, precise microfeature generation was successfully accom plished on both the samples with minimal dimensional deviations on LPBF sample. Thus, the outcomes of the study establish the potential of UPDT in elevating the bioimplant surface standards of beta-Ti alloy with superior performance in LPBF samples.

Keywords
Additive manufacturing; Powder bed fusion; Diamond turning; Titanium; Microstructure

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2025.01.15

A joint research with Yamaguchi University School of Medicine that elucidated that methylglyoxal inhibits fracture treatment through osteoblast differentiation was published in Biochemical and Biophysical Research Communications.

Tetsuya Seto, Kiminori Yukata, Shunya Tsuji*, Yusuke Takeshima, Takeshi Honda, Akihiko Sakamoto, Kenji Takemoto, Hiroki Sakai, Mayu Matsuo, Yurika Sasaki, Mizuki Kaneda, Mikako Yoshimura, Atsushi Mihara, Kazuya Uehara, Aira Matsugaki, Takayoshi Nakano, Koji Harada, Yoshiro Tahara, Keiko Iwaisako, Ryoji Yanai, Norihiko Takeda, Takashi Sakai, Masataka Asagiri*:
Methylglyoxal compromises callus mineralization and impairs fracture healing through suppression of osteoblast terminal differentiation,
Biochemical and Biophysical Research Communications, 747, (2025), 151312; 1-8.
https://doi.org/10.1016/j.bbrc.2025.151312

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Abstract
Impaired fracture healing in diabetic patients leads to prolonged morbidity and increased healthcare costs. Methylglyoxal (MG), a reactive metabolite elevated in diabetes, is implicated in various complications, but its direct impact on bone healing remains unclear. Here, using a non-diabetic murine tibial fracture model, we demonstrate that MG directly impairs fracture healing. Micro-computed tomography revealed decreased volumetric bone mineral density in the callus, while callus volume remained unchanged, resulting in a brittle bone structure. This was accompanied by reduced expression of osteocalcin and bone sialoprotein, both critical for mineralization. Biomechanical analysis indicated that MG reduced the mechanical resilience of the fracture site without altering its elastic strength, suggesting that the impairment was not primarily due to the accumulation of advanced glycation end-products in the bone extracellular matrix. In vitro studies confirmed that non-cytotoxic concentrations of MG inhibited osteoblast maturation and mineralization. Transcriptomic analysis identified downregulation of Osterix, a key transcription factor for osteoblast maturation, without altering Runx2 levels, leading to decreased expression of key mineralization-related factors like osteocalcin. These findings align with clinical observations of reduced circulating osteocalcin levels in diabetic patients, suggesting that the detrimental effects of MG on osteoblasts may extend beyond bone metabolism. Our study highlights MG and MG-sensitive pathways as potential therapeutic targets for improving bone repair in individuals with diabetes and other conditions characterized by elevated MG levels.

Keywords
Fracture healing; Osteoblasts; Diabetes; Methylglyoxal

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2025.01.14

Acta Biomaterialia (IF=9.4) published an article on induction of bone orientation by zebra coating with MPC polymer.

Tadaaki Matsuzaka, Aira Matsugaki*, Kazuhiko Ishihara, Takayoshi Nakano*:
Osteogenic tailoring of oriented bone matrix organization using on/off micropatterning for osteoblast adhesion on titanium surfaces, Acta Biomaterialia, 192, (2025), 39644943; 487-500.
https://doi.org/10.1016/j.actbio.2024.12.017

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Abstract
Titanium (Ti) implants are well known for their mechanical reliability and chemical stability, crucial for suc cessful bone regeneration. Various shape control and surface modification techniques to enhance biological activity have been developed. Despite the crucial importance of the collagen/apatite bone microstructure for mechanical function, antimicrobial properties, and biocompatibility, precise and versatile pattern control for regenerating the microstructure remains challenging. Here, we developed a novel osteogenic tailoring stripe- micropatterned MPC-Ti substrate that induces genetic-level control of oriented bone matrix organization. This biomaterial was created by micropatterning 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer onto a titanium (Ti) surface through a selective photoreaction. The stripe-micropatterned MPC-Ti substrate establishes a distinct interface for cell adhesion, robustly inducing osteoblast cytoskeleton alignment through actin cyto skeletal alignment, and facilitating the formation of a bone-mimicking-oriented collagen/apatite tissue. More over, our study revealed that this bone alignment process is promoted through the activation of the Wnt/ β-catenin signaling pathway, which is triggered by nuclear deformation induced by strong cellular alignment guidance. This innovative material is essential for personalized next-generation medical devices, offering high customizability and active restoration of the bone microstructure.

Keywords
Photoreactive; MPC polymer; Stripe-micropatterned titanium substrate; Osteoblast orientation; Apatite/collagen orientation; Bone regeneration

 

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2025.01.08

The paper on "Superposition of 'material (crystal orientation)' and 'shape' by AM to express mechanical functions", a result of JST-Crest, has been accepted by Acta Materialia (Elsevier, IF=8.3). The paper was published as an OA paper.

Takuya Ishimoto, Naotaka Morita, Ryosuke Ozasa, Aira Matsugaki, Ozkan Gokcekaya, Shota Higashino, Masakazu Tane, Tsuyoshi Mayama, Ken Cho, Hiroyuki Y. Yasuda, Masayuki Okugawa, Yuichiro Koizumi, Masato Yoshiya, Daisuke Egusa, Taisuke Sasaki, Eiji Abe, Hajime Kimizuka, Naoko Ikeo, Takayoshi Nakano*:
Superimpositional design of crystallographic textures and macroscopic shapes via metal additive manufacturing--Game-change in component design, Acta Materialia, 286, (2025), 120709; 1-12.
DOI: https://doi.org/10.1016/j.actamat.2025.120709

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Abstract
This study demonstrates the control of the crystalline orientation through metal additive manufacturing, enabling the development of component design guidelines that incorporate the inherent anisotropy of the me chanical properties (e.g., Young's modulus) in crystalline materials. We, for the first time, successfully fabricated a <111>//build direction (BD)-oriented single-crystalline-like texture in an alloy with a cubic crystal structure via laser powder bed fusion (LPBF) and completed a series of three single-crystalline-like microstructures with <001>, <011>, and <111>//BD orientations in a single material. The <001>and <111>directions exhibited the lowest and highest Young's moduli, respectively, demonstrating a wide range of control over the anisotropy of the mechanical properties of the product. To achieve a <111>//BD-oriented single-crystalline-like texture, a novel three-layer cyclic strategy of "uni"directional laser scanning at 120◦ angular intervals was developed by considering the easy growth direction and crystal symmetry. To the best of our knowledge, no previous study has reported this unique strategy. By superimposing the realized <111>orientation and shape-based anisotropy, products exhibiting high Young's modulus anisotropy, which cannot be expressed by shape and texture alone, were obtained via the LPBF single process. This achievement holds promise for the realization of a new component design guideline that integrates texture (mechanical properties) design for each internal location--modifiable through scanning strategies--with traditional shape optimization techniques typically used in computer-aided design. This approach enables tailored mechanical performance through optimized design strategies.

Keywords
Laser powder bed fusion; Shape anisotropy; Crystallographic orientation; Superimposition; 3D puzzle; Young's modulus

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2024.12.18

The Journal of Materials Engineering and Performance published an article on the effect of energy density on the functionality of Ti6Al-4V alloys formed by AM.

H. Yilmazer, Y. A. Sadikoglu, S. Kucuk, O. Gokcekaya, I. C. Turu, T. Nakano, B. Dikici*:
The effect of energy density on microstructural, mechanical, and corrosion characteristics of Ti6Al-4V alloy fabricated via selective laser melting (SLM) and electron beam melting (EBM) techniques,
Journal of Materials Engineering and Performance, (2024), 1-13.
https://doi.org/10.1007/s11665-024-10512-8

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Abstract
In this study, the effect of production parameters on Ti-6Al-4V alloys fabricated using selective laser melting (SLM) and electron beam melting (EBM) techniques was investigated. Through the variation of energy volume (12.5, 25, 37.5 J mm−3), these two additive manufacturing methods were compared in terms of microstructure, mechanical, and corrosion properties. Density was calculated using Archimedes' technique, while microstructure was characterized through optical microscopy (OM) and scanning electron microscopy (SEM). Mechanical properties were determined via micro-Vickers hardness and tensile tests. Electron backscatter diffraction (EBSD) and x-ray diffraction (XRD) analyses were performed on EBM and SLM samples for a comprehensive understanding. Corrosion susceptibilities of the alloys were evaluated using potentiodynamic scanning (PDS) tests in a 3.5% NaCl solution at room temperature. Microstructural analysis revealed that SLM-produced parts predominantly consisted of the α′ (martensite) phase, whereas EBM-produced parts primarily comprised the α phase with a small amount of the β phase. The strength values of all SLM samples exceeded 930 MPa, surpassing those of wrought Ti-6Al-4V ELI. However, only EBM samples fabricated with a 37.3 J mm−3 energy volume approached this standard. Corrosion susceptibility generally increased with higher energy volume in both EBM and SLM samples, with porosity volume and grain size variations influencing corrosion behavior.

Keywords
Corrosion; EBM; Energy density; Phase transformation; SLM; Ti-6Al-4V

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2024.12.05

The Journal of Alloys and Compounds published an OA paper on the results of joint research with Northeastern University, China.

Chenyang Wu, Xiaoli Zhao*, Takayoshi Nakano, Mitsuo Niinomi, Nan Jia, Deliang Zhang:
Grain size dependence of deformation behavior in Ti-15Mo alloy prepared by powder metallurgy
Journal of Alloys and Compounds, 1010, (2025), 177825: 1-12.
https://doi.org/10.1016/j.jallcom.2024.177825

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Abstract
To the best of our knowledge, this is the first report demonstrating grain refinement to 4 μm via a mass-production method for the Ti-15Mo alloy. Grain sizes ranging from 4 to 38 μm were achieved by controlling thermomechanical processing in powder metallurgy, combined with heat treatment using recycled coarse powders for additive manufacturing. The critical grain size for deformation twinning was investigated, alongside an analysis of the deformation behavior and mechanical properties of the Ti-15Mo alloy with various grain sizes. Upon refining the grain size to 7 μm, deformation twinning is inhibited, shifting the plastic deformation mechanism from mechanical twinning to dislocation slip. The yield strength can be adjusted between 921 and 715 MPa, with elongation ranging from 18.4% to 34.4%, by varying the grain size distribution ratio of small to large grains relative to 7 μm from 1.5 to 0.42. This strengthening effect primarily arises from dislocation strengthening, Mo solid solution, texture strengthening, and modifications in the Hall-Petch constant due to changes in deformation behavior during grain refinement.

Keywords
Ti-Mo alloy; Power Metallurgy; Grain refinement; Mechanical properties; Mechanical twinning

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2024.12.05

A paper on microstructural changes and high temperature mechanical properties of titanium alloys was published in Materials Transactions.

Tomoki Kuroda, Haruki Masuyama, Yoshiaki Toda, Tetsuya Matsunaga, Tsutomu Ito, Makoto Watanabe, Ryosuke Ozasa, Takuya Ishimoto, Takayoshi Nakano, Masayuki Shimojo, Yoko Yamabe-Mitarai:
Microstructure Evolution and High-Temperature Mechanical Properties of Ti-6Al-4Nb-4Zr Fabricated by Selective Laser Melting,
Materials Transactions, 64 [1], (2024), 2022021; 348-356.
DOI: https://doi.org/10.2320/matertrans.MT-MLA2022021

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Abstract
Ti-6Al-4Nb-4Zr (mass%) was prepared by selective laser melting (SLM) under various conditions, and the microstructure evolution resulting from SLM processing and subsequent heat treatments was investigated. The effects of the unique SLM-induced microstructure on the high-temperature compressive strength and creep properties of the samples were then elucidated. Under rapid cooling conditions, the martensitic structure formed in a scale-like pattern, with a 100 µm in size, consistent with the laser scanning pattern. By contrast, under slow cooling conditions, the α/β lamellar structure formed in β grains with a 300 µm grain size instead of in a scale-like pattern. The martensitic structure drastically changed to a Widmanstätten structure during heat treatment. The equiaxed α phase also formed at the interface of the scale-like patterns. By contrast, the α/β lamellar structure did not exhibit a change in response to heat treatment. The compressive strength of the SLM samples was governed by the martensite α size and the grain size, both of which depended on the cooling rate. The dominant creep deformation mechanism at 600°C and under a loading stress of 137 MPa was grain boundary sliding. The creep life depended on the grain size. The HIP treatment improved the creep life because it eliminated pores introduced by the SLM process.

Keywords
selective; lasermelting; heat-resistant; Ti alloys; compression; strength; creep

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2024.11.21

A paper on our recent research on titanium alloys was published in the December issue of Materials Transactions.

Mitsuo Niinomi*, Takayuki Narushima, Takayoshi Nakano:
Recent Research and Development in the Processing, Microstructure, and Properties of Titanium and Its Alloy
Materials Transactions, 65 [12], (2024), 1600-1611.
https://doi.org/10.2320/matertrans.MT-M2024082

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Abstracts
The special issue on recent research and development in the processing, microstructure, and properties of titanium and its alloy contains four review articles on metal additive manufacturing (AM) focusing on the processing, microstructural and/or crystallographic control, and biomedical applications of titanium and its alloys, and seventeen regular articles on metal AM, refining, microstructural evolution, and mechanical and fatigue properties related to the microstructure, and biomedical applications of titanium and its alloys, which have been published in Materials Transactions in 2023. This study briefly addresses this issue.

Keywords
titanium and its alloys; additive manufacturing (AM); phase transformation; microstructure; mechanical properties; titanium based intermetallics; biomaterials; recycling

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