【公開日：2025.06.10】【最終更新日：2025.05.12】
課題データ / Project Data
課題番号 / Project Issue Number
24TU0191
利用課題名 / Title
High-strength alloys
利用した実施機関 / Support Institute
東北大学 / Tohoku 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）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials（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
電子顕微鏡/ Electronic microscope,集束イオンビーム/ Focused ion beam
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)
Louzguine Dmitri Valentinovich
所属名 / Affiliation
国立研究開発法人 産業技術総合研究所
共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes
ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes
兒玉裕美子
利用形態 / Support Type
（主 / Main）技術代行/Technology Substitution（副 / Sub）-
利用した主な設備 / Equipment Used in This Project
TU-517：透過電子顕微鏡
TU-508：集束イオンビーム加工装置
TU-507：集束イオンビーム加工装置
報告書データ / Report
概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)
We produced and studied a new series of Fe–Mn–Co–Ni–Cu–Al–C alloys that demonstrate tensile plasticity up to 10% along with exceptionally high yield strength values reaching 1.5 GPa. These mechanical properties are achieved solely through standard technological processes, including homogenization, hot forging, cold rolling, and tempering/aging. This accomplishment is realized by leveraging the high-entropy/multiprinciple element approach, leading to the formation of a duplex-type cF4 and cI2 solid solution structure.
実験 / Experimental
The alloys of the following compositions (see Table 1), studied in the present work, were prepared by induction melting in an alumina crucible under an argon atmosphere. After that, they were cast into a massive Cu mold forming 20x50x100 mm3 ingots. These ingots were then homogenized in air at 1100 oC for 4 hours and quenched in water to avoid precipitation of carbides. After that, they were cross- cut into a series of rectangular bars of 20x20 mm2 in cross-section. These slabs were subjected to hot dual axial forging (DAF) in several passes at 1050 oC making slabs of 10x10 mm cross-section. After DAF the samples were cut in a longitudinal direction forming 5x10 mm2 cross-section samples which were subsequently cold rolled (CR) (between two SUS steel plates to protect the rolls) to 25 and 50% size reduction. The structure of the samples was examined by X-ray diffractometry (XRD) with Cu Kα radiation and the JEOL JEM 2000 EX TEM. The foils were prepared by Ar ion-beam polishing.
結果と考察 / Results and Discussion
The chemical compositions of the studied alloys in mass percentages are given in Table 1. The alloys are close in composition to high entropy alloys. The studied alloys had a duplex FCC (cF4) + BCC (cI2) structure. Fig. 1 shows the XRD patterns of the studied alloys. Fig. 2 shows tensile stress-strain curves of the Cu2 (a) and Co10 (b) alloys after homogenization, DAF, and cold rolling (CR) for 25% and 50% as well as after additional annealing/tempering as indicated. After annealing for 60 min at 600 oC, the Cu2 and Co10 samples showed high yield strength values of 1292±34 and 1506±45 MPa, respectively. They also showed reasonable tensile plasticity. Considering the density of 6.53±0.03 g/cm3 obtained for the Co10 alloy it showed a very high specific yield strength of 230 Nm/g, respectively. Cu2 alloy with a density of 6.58±0.02 g/cm3 suggests the specific yield strength of 184 Nm/g.Not so many twins and microbands are seen in the TEM images (Fig. 3) indicating that the main strengthening mechanism in the cF4 phase is deformation hardening with dislocations. The fracture surfaces of the Cu2 and Co10 alloys exhibit dimple patterns typical of ductile alloys in tensile tests. Formation of lamellar submicron-scale cF4 phase structure is observed in cross-sectional image after cold-rolling (Fig. 3a,b). At the same time, cI2 grains are broken into smaller pieces on cold rolling (Fig. 3c,d). Also, partial ordering of the crystalline lattice is observed in some cI2 grains (not in every one) as illustrated by weak (100) superlattice reflections seen in Fig. 3d (inset).
図・表・数式 / Figures, Tables and Equations
Table 1. Chemical composition of the studied alloys.
Fig. 1. XRD patterns of the studied alloys (a) in the as-cast and (b) homogenized state, as indicated. Cu Kα radiation. FCC cF4 (●) and BCC cI2 (♦) phases are formed.
Fig. 2. Tensile stress-strain curves of the Cu2 (a) and Co10 (b) alloys after homogenization, DAF, and cold rolling (CR) for 25% and 50% (as indicated) as well as after additional annealing/tempering as indicated. The inset in (b) is the DAF CR25 sample.
Fig. 3. Bright-field (a,c) and dark-field (b,d) TEM images and SAED pattern (insets) of the cF4 phase [110] zone axis (a,b) and partially ordered cI2 phase with [100] zone axis (c,d) of the Cu2 alloy. Cross-sectional TEM observation.
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)
-
V.O. Semin, The effect of some late 3d transition metals additions to a Fe–Mn–Al–C alloy on the development of high-entropy alloys, Intermetallics, 177, 108589(2025).
DOI: https://doi.org/10.1016/j.intermet.2024.108589
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