【公開日：2025.06.10】【最終更新日：2025.04.27】
課題データ / Project Data
課題番号 / Project Issue Number
24KU0043
利用課題名 / Title
CoCrFeMnNi高エントロピー合金における再結晶・相変態のその場TEM観察
利用した実施機関 / Support Institute
九州大学 / Kyushu Univ.
機関外・機関内の利用 / External or Internal Use
外部利用/External Use
技術領域 / Technology Area
【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-
【重要技術領域 / Important Technology Area】（主 / Main）革新的なエネルギー変換を可能とするマテリアル/Materials enabling innovative energy conversion（副 / Sub）次世代ナノスケールマテリアル/Next-generation nanoscale materials
キーワード / Keywords
ハイエントロピー合金
利用者と利用形態 / User and Support Type
利用者名（課題申請者）/ User Name (Project Applicant)
吉田 周平
所属名 / Affiliation
京都大学大学院工学研究科材料工学専攻
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
Guo Baoqi
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
前野宏志
利用形態 / Support Type
（主 / Main）技術補助/Technical Assistance（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
Recrystallization in high entropy alloy has a profound effect on the microstructure evolution and mechanical properties. However, the recrystallization behavior in high entropy alloys was limited to ex-situ observations in which microstructure is observed at room temperature after rapid cooling．However, conventional methods failed to capture the real-time characteristics of recrystallization such as nucleation and growth, so it is very difficult to understand the mechanism of real-time recrystallization though conventional ex-situ techniques. To solve this problem, we used in-situ TEM with a heating stage to study the recrystallization.
実験 / Experimental
The Cantor alloy was first processed by HPT and annealed at 800°C for 3 min so that fine grains can be obtained．Then the samples was cold rolled by 50% in height. The deformed samples were introduced to TEM with a heating state in Kyushu University. The accelerated voltage is 300 kV. The sample was heated to 700°C and 800°C, respectively. The heating rate is 0.5 oC / s. Diffraction patterns were taken to determine the phase transformation．
結果と考察 / Results and Discussion
The initial microstructure prior to heating (Fig. 1(a)) showed that shear bands consisted of ultrafine elongated grains and finely spaced deformation twin bundles were detected after cold rolling．After heating to 700 °C, the boundary movement in some subgrains was detected, i.e. the formation and coarsening of nuclei of recrystallization, as shown in Fig. 1(b). The shear bands served as the preferential sites for nucleation and grain growth. At the same time, precipitation of sigma phase (diffusional phase transformation) was also confirmed in the same areas. The twin area was depleted by the recrystallization derived from shear bands. The bulging behavior of grain boundary was also observed. In the future, more details on the texture evolution will be given.
図・表・数式 / Figures, Tables and Equations
Fig. 1. In-situ TEM observation of Cantor alloy (a) Initial state at room temperature，(b) 700 oC holding for 120 s．
その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)
成果発表・成果利用 / Publication and Patents
論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)
口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.
特許 / Patents
特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件