研究者業績

岡井 大祐

オカイ ダイスケ  (Daisuke Okai)

基本情報

所属
兵庫県立大学 大学院 工学研究科 材料・放射光工学専攻 助教
学位
博士(工学)(山形大学)

J-GLOBAL ID
200901054987023725
researchmap会員ID
1000240358

論文

 71
  • Hiroki Adachi, Tatsuya Kitano, Masahiro Hirata, Daisuke Okai
    Materials Transactions 66(1) 117-122 2025年1月  
    Type-B serrations were observed during room-temperature tensile deformation of Al-2.17 mass%Mg alloy with an average grain size of 12 µm. Digital image correlation was used to visualize Portevin-Le Chatelier (PLC) bands, and microstructural changes in these bands were observed by in-situ X-ray diffraction measurements using synchrotron radiation at SPring-8. The results indicated that the overall density of dislocations, including both mobile and pinned dislocations inside the PLC bands, increased substantially as the bands formed. This suggests that serration occurs due to an increase in the mobile dislocation density resulting from the formation of new dislocations from sources inside the PLC bands.
  • Mizuho Kondo, Tatsuki Nagata, Yukitaka Hyodo, Daisuke Okai, Hiroki Adachi, Nobuhiro Kawatsuki
    Chemistry Letters 2024年4月4日  
    Abstract Adhesive layers were prepared using photoreactive polymer liquid crystals, and their application as dismantled adhesives based on the change in thermal properties associated with photoisomerization was investigated. Anisotropy in adhesive strength was successfully achieved by controlling the alignment of the liquid crystal using a polyimide alignment film. Furthermore, anisotropy in the adhesive strength due to photoalignment was investigated using the axis-selective photoreactivity of polymer liquid crystals to linearly polarized light.
  • 足立 大樹, 北野 竜也, 平田 雅裕, 岡井 大祐
    軽金属 73(12) 628-632 2023年12月  査読有り
  • Masahiro Hirata, Koichi Iwata, Daisuke Okai, Hiroki Adachi
    Materials Transactions 64(11) 2584-2590 2023年11月  査読有り
    Al-Zn-Mg alloys with different precipitate sizes were investigated to determine the influence of the precipitate size on the flow stress and dislocation density change during tensile deformation. The dislocation density was measured using in-situ X-ray diffraction at the SPring-8 synchrotron radiation facility with a time resolution of about 2 s. In region II with rapid dislocation multiplication, from under-aging to peak aging, the dislocation density increased with increasing aging time. Under over-aging conditions, the amount of dislocation multiplication in region II decreased with increasing aging time. Even in region III, the increase in dislocation density with plastic deformation was the largest for the peak aging conditions. However, the amount of work hardening was small and the contribution of dislocation hardening to the strength of the material was minimal. For over-aging conditions, the increase in dislocation density in region III was smaller than for the other regions, but the amount of work hardening was relatively large. It is considered that the influence of the dislocation density on work hardening is determined by the effectiveness of precipitates as obstacles to dislocation motion.
  • Mizuho Kondo, Shika So, Tatsuki Nagata, Hiroki Adachi, Daisuke Okai, Nobuhiro Kawatsuki
    2022 29th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD) 2022年7月5日  査読有り

MISC

 53

講演・口頭発表等

 96

共同研究・競争的資金等の研究課題

 12

産業財産権

 1