中野研究室2026-04-17T12:44:25ZMovable Type Pro【行事】中野研究室の新B4歓迎会が行われました。2026-04-17T11:44:34Z2026-04-17T11:44:34Z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...
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！！
Abstract In this study, laser cavitation peening without coating (LCPwC) was employed to enhance the wear resistance of Ti-30Zr-5Mo alloy for implant applications by inducing a multiscale gradient surface structure through laser-water interaction and surface oxidation. LCPwC was performed at pulse densities of 10, 50, and 100 pulses/mm2, producing an oxide layer comprising TiO2, Ti2O3, and ZrO2. With increasing pulse density, the TiO2 fraction decreased from 76.8% to 56.9%, whereas the Ti2O3 and ZrO2 fractions increased from 6.7% to 20.9% and from 5.1% to 13.8%, respectively. The oxide layer exhibited a nanograined structure, and the average grain size decreased from 12.1 to 9.1 nm before increasing slightly to 9.5 nm, suggesting initial grain refinement followed by limited grain growth at higher pulse densities. The surface roughness increased from 0.4 μm for the untreated alloy to 1.5-4.0 μm after treatment, while the water contact angle increased from 64.9° to 121.2-130.1°, indicating increased surface hydrophobicity. The surface microhardness increased from 290 HV for the untreated alloy to 360, 392, and 403 HV after treatment, and the residual compressive stress increased in magnitude from −74 to −179 MPa. Wear testing showed that the specimen treated at 10 pulses/mm2 exhibited improved tribological performance, with a 26.2% reduction in wear volume, a 50% reduction in wear mass, and a decrease in the coefficient of friction from 0.56 to 0.12. These improvements were mainly attributed to the formation of a protective oxide layer and the increase in surface hardness induced by LCPwC. Overall, LCPwC is an effective strategy for improving the tribological performance of Ti-30Zr-5Mo alloy and represents a promising approach for implant surface modification.
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【講演】Changwon National UniversityのProf. Jehyun Leeが訪問され、特別講演会を行いました。2026-04-17T03:27:53Z2026-04-17T03:27:53ZProf. Jehyun Lee：Principles of Solidific...
Prof. Jehyun Lee：Principles of Solidification ～Solidification from snow, ice cream to single crystal and AM in superalloys
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【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）に受理されました。2026-04-15T00:03:01Z2026-04-15T00:03:01ZNaoki Nohira*, Cheng Chen, Yilin Jin, Wa...
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), in press.]]>
【新B4配属】中野研へ新B4として9名の配属が決定しました。2026-04-10T11:44:34Z2026-04-10T11:44:34Z新B4奥村 志真 君角田 兼志郎 君木村 結月 さん佐々木 皓政 君社領 勇司郎...新B4
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【論文】Journal of Materials Research and Technology（IF=6.6）にLPBFによるTiAlの層状組織の方向制御に関する論文がOA論文として掲載されました。2026-04-02T00:25:37Z2026-04-02T00:25:37ZSung-Hyun Park, Ozkan Gokcekaya, Kazuhis...
Sung-Hyun Park, Ozkan Gokcekaya, Kazuhisa Sato, Ji-Sung Park, Chae-Won Kim, Myung-Hoon Oh, Seong-Woong Kim*, Takayoshi Nakano*: Formation of a bi-directional α₂/γ lamellar microstructure through crystallographic texture control in a γ-TiAl alloy fabricated by laser powder bed fusion, Journal of Materials Research and Technology, 42 (2026) 2625-2637.
Abstract This study presents, for the first time, a bi-directional α₂/γ lamellar microstructure achieved in a γ-titanium aluminide (γ-TiAl) alloy via laser powder bed fusion (LPBF). In the as-built condition, the microstructure was predominantly composed of the α₂ phase, in which a crystallographic lamellar microstructure (CLM) consisting of two differently oriented crystallographically textured layers was established. In the major layer, the {0001} direction was oriented perpendicular to the building direction (BD), whereas in the minor layer, it was nearly aligned parallel to the BD. After heat treatment the previously formed CLM was preserved, thereby governing the orientation of the subsequently formed α₂/γ lamellae according to the Blackburn orientation relationship. Therefore, a bi-directional α2/γ lamellar microstructure was obtained, with lamellae oriented parallel (0°) and perpendicular (90°) to the BD in the major and minor layers, respectively. The individual nano-hardness measurements revealed values of 9.3 ± 0.4 GPa for the major layer and 10.4 ± 0.8 GPa for the minor layer, which are much higher than those of γ-TiAl alloys produced by other processing methods. This unique microstructural formation was primarily enabled by a peritectic reaction-based alloy design combined with process-induced crystallographic texture control, highlighting a new pathway for microstructural design of γ-TiAl alloys and potentially enabling improved mechanical performance.
Keywords γ-titanium aluminide; Laser powder bed fusion; Crystallographic texture; Peritectic reaction; Directional lamellar microstructure ]]>
【論文】Journal of Materials Research and Technology（IF=6.6）にLPBFによるTiAlの層状組織の方向制御に関する論文が受理されました。2026-04-01T02:23:23Z2026-04-01T02:23:23ZSung-Hyun Park, Ozkan Gokcekaya, Kazuhis...Sung-Hyun Park, Ozkan Gokcekaya, Kazuhisa Sato, Ji-Sung Park, Chae-Won Kim, Myung-Hoon Oh, Seong-Woong Kim*, Takayoshi Nakano*: Formation of a bi-directional α₂/γ lamellar microstructure through crystallographic texture control in a γ-TiAl alloy fabricated by laser powder bed fusion, Journal of Materials Research and Technology, (2026), in press.
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