Plastic deformation and microstructural evolution during cryogenic charpy impact of high-Mn austenitic steel

Jiang, L.*; Wang, H. H.*; Su, Y. H.; 徐 平光; 篠原 武尚; Xia, B.*; Wang, Y. W.*

Journal of Materials Science, 61(14), p.9754 - 9775, 2026/04

https://doi.org/10.1007/s10853-026-12472-x

In this study, pulsed neutron Bragg-edge transmission imaging was employed to characterize plastic deformation of high-manganese austenitic steel during cryogenic impact fracture. Electron backscatter diffraction was used to examine the microstructural evolution. The results reveal that the Bragg-edge width was identified as the critical value for large plastic deformation. Both crack initiation and stable crack growth regions exhibited higher levels of plastic deformation, twin density, and dislocation density compared to unstable crack growth regions. As the test temperature decreased from 273 K to 77 K, the transition point from stable to unstable crack growth occurred earlier. This is responsible for the reduction in impact absorbed energy. These findings provide new insights into the cryogenic toughening mechanism of high-manganese steel.

Magnetic order of Dresselhaus-type antiferromagnet EuIrInGe studied by single crystal neutron diffraction

田端 千紘; 金子 耕士; 中尾 朗子*; 大原 高志; 松田 達磨*; 大貫 惇睦*

Journal of the Physical Society of Japan, 95(5), p.053702_1 - 053702_4, 2026/04

https://doi.org/10.7566/JPSJ.95.053702

The magnetic order of EuIrInGe, which crystallizes in a Dresselhaus-type noncentrosymmetric tetragonal structure, was investigated using two complementary single-crystal neutron diffraction approaches. Time-of-flight single-crystal diffraction reveals antiferromagnetic Bragg reflections with propagation vector q = (0, 0, 0) below the Neel temperature TN = 2.5 K, indicating a breaking of body-centered translational symmetry. Polarized neutron diffraction on a triple-axis spectrometer demonstrates that the ordered Eu2+ 4f moments lie within the basal plane and form a collinear antiferromagnetic structure with antiparallel alignment between corner and body-center sites. Despite the Dresselhaus-type spin splitting in the conduction bands, the magnetic order remains simple, implying weak coupling between localized moments and itinerant electrons.

加速器冷却水設備における防錆剤変更による電蝕の抑制; 腐食とコストの削減

出井 竜美; 菅沼 和明; 藤来 洸裕; 鈴木 勝夫; 鈴木 博*; 仲田 守浩*; 細川 英洸*; 小野瀬 勇一郎*; 渡辺 泰広; 篠崎 信一; et al.

JAEA-Technology 2026-003, 27 Pages, 2026/03

JAEA-Technology-2026-003.pdf:1.3MB

加速器冷却水設備配管系統は異なる金属で構成されることも多いため電蝕が不可避である。本試験では、まず無酸素銅と炭素鋼の間で電蝕が起こること、またこれまで使用されてきた防錆剤ではその電蝕の抑制ができないことを確認した。次に新たに導入した防錆剤による電蝕の抑制を確認した。また新しい防錆剤に変更することにより、補給水の節水および防錆剤コスト削減が実現できた。

Revisiting the role of NbO precursors on solid-state formation reactions of (KNa)NbO

庄司 琢磨*; Nam, H.*; Ye, J.*; Ito, Daiki*; 高木 優香*; 米田 安宏; 永田 肇*

Journal of the American Ceramic Society, 109(3), p.e70657_1 - e70657_9, 2026/03

https://doi.org/10.1111/jace.70657

(K,Na)NbO (KNN)系セラミックスは、優れた圧電特性を有するにもかかわらず、化学的均質性が低いことから、実用的な圧電デバイスへの応用には躊躇されてきた。本研究では、NbO前駆体の役割が製造手法によって異なり、KNNの化学的均質性と強く相関していることを軟X線吸収分光を用いて明らかにした。したがって、NbO前駆体の選択はKNN製造における支配的要因である。

Coupled dimerized alternating-bond quantum spin chains in the distorted honeycomb-lattice magnet CuSbO

Piyakulworawat, C.*; 森田 克洋*; 福元 好志*; Hsieh, W.-Y.*; Chen, W.-T.*; 中島 健次; 河村 聖子; Zhao, Y.*; Wannapaiboon, S.*; Piyawongwatthana, P.; et al.

Physical Review Research (Internet), 8(1), p.013247_1 - 013247_16, 2026/03

https://doi.org/10.1103/vdgg-d128

歪んだハニカム化合物CuSbOの中性子非弾性散乱および磁化データを、一次のダイマー展開計算と量子モンテカルロシミュレーションを用いて解析した。これまでに提案されたハニカム格子モデルとは対照的に、この系は相互作用するダイマースピン鎖を有し、鎖に沿って強磁性-反強磁性結合が交互に現れることが示された。さらに、他のCuベースの歪んだハニカム磁性体で観測される典型的な結合とは異なり、スピン鎖は、予想される層間の鎖間結合ではなく、主にハニカム層間に生じる反強磁性結合を介して結合する。つまり、CuSbOの磁気結合スキームが異なることが明らかになった。さらに、X線分光法と透過型電子顕微鏡を利用して、化合物の結晶構造と積層欠陥モデルも従来のモデルをより精密化した。

Super-ductile magnesium alloy at room temperature

Li, H.*; Gong, W.; 川崎 卓郎; Harjo, S.; Zheng, R.*; 他6名*

Acta Materialia, 305, p.121884_1 - 121884_10, 2026/02

https://doi.org/10.1016/j.actamat.2025.121884

The quest for lightweight and highly formable magnesium (Mg) alloys has drawn significant attention due to the growing demand for energy-efficient structural materials. Achieving high ductility in Mg at room temperature, which is critical for mass production of structural components, remains a formidable challenge despite decades of research. In this study, we demonstrate super-ductility in an ultrafine-grained (UFG) Mg alloy at room temperature. By microalloying with trace manganese (Mn) and reducing the grain size to sub-micron scale, Mg-0.3Mn binary alloy achieves an exceptional room temperature tensile elongation of 135% at a quasi-static strain rate. Detailed microstructural analysis reveals that grain boundary (GB) sliding, rather than intragranular dislocation slip, is the dominant deformation mechanism in the UFG Mg-0.3Mn alloy. Unlike conventional alloying strategies that lead to GB pinning, the segregation of Mn element along GBs in a manner of nano-clusters could reduce interfacial bonding strength, acting as a lubricant to facilitate GB sliding and thus dramatically boost the ductility. This innovative GB engineering approach unlocks unprecedentedly remarkable deformability of Mg-based alloys at room temperature, paving the way for next-generation lightweight structural applications.

Facile preparation of antiviral grafted fabrics based on silver-immobilized phosphate groups and evaluation of COVID-19 infections

松村 大樹; 辻 卓也; 瀬古 典明*; 他5名*

Journal of Radioanalytical and Nuclear Chemistry, 335(2), p.1543 - 1552, 2026/02

https://doi.org/10.1007/s10967-025-10608-y

The COVID-19 pandemic has underscored the need for protective materials with rapid and durable antiviral properties. We developed silver (Ag)-immobilized fabrics via radiation-induced graft polymerization and tested their activity against SARS-CoV-2. The fabrics reduced 40,000 viral particles to below detection within one hour, showed no Ag leaching after 24 h in water, and retained complete antiviral performance after one year of storage. These findings demonstrate the long-term stability and strong potential of Ag-immobilized fabrics for industrial use in protective equipment.

Field-induced quantum first-order transition in a two-dimensional frustrated antiferromagnet

藤原 理賀; 萩原 雅人; 石角 元志*; Sari, D. P.*; 渡邊 功雄*; 髭本 亘; 田端 千紘; 金子 耕士

Physical Review B, 113(6), p.064409_1 - 064409_8, 2026/02

https://doi.org/10.1103/7nqp-9m4x

We report a field-induced quantum first-order transition in the antiferromagnet KCoPOHO. Using highly oriented microcrystals with , polarized neutron diffraction directly reveals coexistence of an incommensurate cycloid and a commensurate collinear state, together with a discontinuous jump of the ordering wave vector from incommensurate to commensurate. Magnetization and specific heat show a step and a collapse of the anomaly near ~T with no measurable hysteresis, while LF-SR detects two-component relaxation and slow fluctuations around . The - phase diagram exhibits a narrow coexistence region. Symmetry of space group constrains the DM vector to the plane and, together with XY anisotropy, nearly degenerates the incommensurate and commensurate states, enabling a first-order switch in field. KCoPOHO thus serves as a platform for quantum first-order transitions in frustrated magnets.

Effect of nanoscale cellular structure on the mechanical properties of Inconel 718 with unique hierarchical structure fabricated by laser powder bed fusion

Cho, K.*; 山下 葵平*; 角谷 心之輔*; 齊藤 拓馬*; 佐々木 泰祐*; 澤泉 克彦*; 奥川 将行*; 小泉 雄一郎*; 眞山 剛*; 菊川 泰地*; et al.

Acta Materialia, 303, p.121696_1 - 121696_18, 2026/01

https://doi.org/10.1016/j.actamat.2025.121696

The deformation behavior and strengthening mechanism of Inconel 718 with a hierarchical structure composed of microscale crystallographic lamellar microstructure (CLM) and nanoscale cellular structure, fabricated by laser powder bed fusion, were clarified via nanoscale microstructural and in-situ neutron diffraction analyses. The CLM is a layered structure parallel to the building direction (BD) and consists of relatively wide main and narrow sub-layers with 110 and 100 orientations, respectively, with respect to BD. This is the first study to demonstrate that the yield stress of the alloys depends strongly on deformation stresses of the sub-layers, even though Schmid factors of the primary slip system for both layers are the same. The sub-layer continues to deform elastically even beyond the micro-yield point of the main layer, which results in the macroscopic strengthening at an early stage of deformation. On the other hand, the cellular structure is formed in both layers, associated with a dendritic cell growth along 100 direction, Nb segregation between the cells and an accumulation of dislocations to decrease a residual stress. The cell boundaries with numerous dislocations and Nb segregation act as a strong barrier to dislocation motion resulting in a stress increase through the Hall-Petch law, even though they are low-angle grain boundaries. The spacing and morphology of the cell boundary depend strongly on fabrication conditions. The optimized cellular structure provides significant strengthening comparable to or greater than that caused by large-angle grain boundaries, thereby increasing the macroscopic strength of the alloys through hardening of the sub-layer.

Residual stress relief effect in gradient structural steel and remaining life evaluation under stochastic fatigue loads

Qin, T. Y.*; Hu, F. F.*; 徐 平光; Zhang, R.*; Su, Y. H.; Ao, N.*; Li, Z. W.*; 篠原 武尚; 菖蒲 敬久; Wu, S. C.*

International Journal of Fatigue, 202, p.109233_1 - 109233_16, 2026/01

https://doi.org/10.1016/j.ijfatigue.2025.109233

The surface induction-hardened S38C medium carbon steel shows a good balance of strength and toughness, but complicates the evaluation of fatigue resistance, mainly because of gradient residual stress (RS) and grains. An integrated fatigue resistance assessment (AIFA) framework was proposed to consider the residual stress relief under stochastic loads. To this end, quasi-in situ neutron diffraction and Bragg-edge imaging were combined to probe the evolution of residual stress during crack propagation. Firstly, a rigid-flexible coupled vehicle dynamics model was adopted to obtain the time-domain variable amplitude loading spectrum. Then, Fortran subroutines were developed to assign these data into full-scale S38C axle model, and the remaining life was predicted using the damage tolerance approach. The results demonstrate that crack propagation would accelerate when residual stress is considered in the case of the crack depth exceeding 3.0 mm. It is, for the first time, found that 15 mm- and 5 mm-thickness fan-shaped specimens can retain the axial and hoop residual strain in terms of diffraction angle variation, respectively, for full-scale structural S38C steel axles. In the absence of RS, the remaining life of the axle decreases sharply from 624,800 to 51,300 km as the crack depth increases from 3.0 to 16 mm. Compared with the standard method under constant amplitude loading without residual stress relief, the present AIFA method provides the more accurate but conservative fatigue life prediction.