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論文

Enhancing mechanical properties of medium Mn steel by warm rolling based on laminated elemental segregation

Chen, H. F.*; Liu, B. X.*; 徐 平光; Fang, W.*; Tong, H. C.*; Yin, F. X.*

Journal of Materials Research and Technology, 32, p.3060 - 3069, 2024/09

 被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)

The hot-rolled microstructure of medium Mn steel has coarse grains and severe elemental segregation, resulting in low strength and plasticity. Constructing a multiphase structure, refining the microstructure, and regulating elemental segregation enhance the mechanical properties. In this study, liquid nitrogen treatment created a layered distribution of austenite and martensite. Warm rolling was then used to reduce layer thickness and refine grain structure. After liquid nitrogen and warm rolling treatments, the strength and plasticity of medium Mn steel increased to 1270 MPa and 23.3%, respectively, far exceeding the hot-rolled state (724 MPa, 12.8%). Warm rolling also triggers austenite reverted transformation (ART) and introduces high-density dislocations, further improving austenite stability. This strengthening effect is higher than that from intercritical annealing alone. Improved austenite stability delays the transformation induced plasticity (TRIP) effect, preventing brittle fracture and enhancing deformation coordination between layers, significantly increasing the plastic deformation capacity of medium Mn steel.

論文

Influence of interstitial carbon on bulk texture evolution of carbide-free high-entropy alloys during cold rolling using neutron diffraction

Fang, W.*; Liu, C.*; Zhang, J.*; 徐 平光; Peng, T.*; Liu, B.*; 諸岡 聡; Yin, F.*

Scripta Materialia, 249, p.116046_1 - 116046_6, 2024/08

 被引用回数:2 パーセンタイル:67.89(Nanoscience & Nanotechnology)

The influence of interstitial carbon on the texture evolution of high-entropy alloys during cold rolling was investigated. To prevent carbide formation, elements with weak carbon affinity were carefully selected in the (FeMnCoNi)$$_{96.5}$$C$$_{3.5}$$ alloy. Neutron diffraction, electron channeling contrast imaging, and electron backscatter diffraction were used to analyze the texture and microstructure evolution in alloys with and without carbon addition. Though their texture components are similar at the early stage of deformation, the Brass and Goss textures in the carbon-containing alloy at 50% cold rolling reduction are obviously higher than those in the carbon-free alloy, while Copper and S textures are lower. A large number of deformation twins induced in the carbon containing alloy is attributed as the significant reason for the texture differences. This work helps to understand the impact of interstitial carbon on the texture evolution of high-entropy alloys, providing valuable insights for microstructure and performance optimization.

論文

Phase transformation and equation of state in Ti-45Al alloy under high pressure

Li, X.*; Zhu, R.*; Xin, J.*; Luo, M.*; Shang, S.-L.*; Liu, Z.-K.*; Yin, C.*; 舟越 賢一*; Dippenaar, R. J.*; 肥後 祐司*; et al.

CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 84, p.102641_1 - 102641_6, 2024/03

 被引用回数:0 パーセンタイル:0.00(Thermodynamics)

The phase transformations and pressure-volume dependencies of the Ti-45Al alloy with respect to pressure have been investigated by means of in-situ observation using multi anvil-type high-pressure devices and synchrotron radiation. Under hydrostatic compression from 0 to 10.1 GPa, about 2.3 vol. % of $$gamma$$ transforms continuously to $$alpha$$2. Lattice parameters as well as volume fractions of these two phases have been determined as a function of pressure. Bulk moduli estimated using Birch-Murnaghan's equation of state are 148 GPa for the $$gamma$$ phase, 138 GPa for the $$alpha$$2 phase, and 149 GPa for their two-phase mixture of Ti-45Al alloy. First-principles have also applied to investigate bulk moduli of two single phases, and the deviation between calculations and measurements is discussed and attributed to mainly phase transformation. The presently study provides useful insights into thermodynamics of $$alpha$$2 and $$gamma$$ phases under high pressure.

論文

The BCC $$rightarrow$$ FCC hierarchical martensite transformation under dynamic impact in FeMnAlNiTi alloy

Li, C.*; Fang, W.*; Yu, H. Y.*; Peng, T.*; Yao, Z. T.*; Liu, W. G.*; Zhang, X.*; 徐 平光; Yin, F.*

Materials Science & Engineering A, 892, p.146096_1 - 146096_11, 2024/02

 被引用回数:4 パーセンタイル:78.83(Nanoscience & Nanotechnology)

The quasi-static superelastic responses and hierarchical martensite transformation from body-centered cubic (BCC) to face-centered cubic (FCC) under dynamic impact in Fe$$_{42}$$Mn$$_{34}$$Al$$_{15}$$Ni$$_{7.5}$$Ti$$_{1.5}$$ alloys were investigated. Polycrystalline and oligocrystalline alloys were produced through solution heat treatment and cyclic heat treatment processes, respectively. The results show the volume fraction of residual martensite for oligocrystalline alloys is lower, which exhibits better superelastic responses compared with polycrystalline alloys. Dynamic impact tests indicate that, despite the weakening of the grain boundary strengthening effect, the ultimate strength of the oligocrystalline alloys closely matches that of the polycrystalline alloys under dynamic impact. The martensite transformation of the FeMnAlNiTi alloy is characterized as hierarchical under dynamic impact, and increasing strain rates and grain sizes can enhance the BCC $$rightarrow$$ FCC martensite transformation, resulting in higher martensite phase fractions for oligocrystalline alloys. The increase in ultimate strength is attributed to the dynamic Hall-Petch effect introduced by more martensite phase interfaces under dynamic impact.

論文

Stacking fault driven phase transformation in CrCoNi medium entropy alloy

He, H.*; Naeem, M.*; Zhang, F.*; Zhao, Y.*; Harjo, S.; 川崎 卓郎; Wang, B.*; Wu, X.*; Lan, S.*; Wu, Z.*; et al.

Nano Letters, 21(3), p.1419 - 1426, 2021/02

 被引用回数:68 パーセンタイル:96.32(Chemistry, Multidisciplinary)

In CrCoNi, a so-called medium-entropy alloy, an fcc-to-hcp phase transformation has long been anticipated. Here, we report an in situ loading study with neutron diffraction, which revealed a bulk fcc-to-hcp phase transformation in CrCoNi at 15 K under tensile loading. By correlating deformation characteristics of the fcc phase with the development of the hcp phase, it is shown that the nucleation of the hcp phase was triggered by intrinsic stacking faults. The confirmation of a bulk phase transformation adds to the myriads of deformation mechanisms available in CrCoNi, which together underpin the unusually large ductility at low temperatures.

論文

Selective removal of radiocesium from micaceous clay for post-accident soil decontamination by temperature-controlled Mg-leaching in a column

Yin, X.; Zhang, L.*; Meng, C.*; 稲葉 優介*; Wang, X.*; 二田 郁子; 駒 義和; 竹下 健二*

Journal of Hazardous Materials, 387, p.121677_1 - 121677_10, 2020/04

 被引用回数:13 パーセンタイル:46.31(Engineering, Environmental)

The effective and efficient removal of radioactive Cs from contaminated soil is highly urgent for the nuclear post-accident remediation. In present study, we achieved rapid Cs desorption from both a typical micaceous clay (i.e., vermiculitized biotite, VB) and actually contaminated soil by high-speed ion exchange through temperature-controlled continuous leaching with Mg-solutions in a column reactor. Cs-sorbed VB was firstly employed as a soil surrogate to explore the macro-Cs desorption process and micro-mechanism in detail.

論文

Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs

Xu, Z.*; Dai, G.*; Li, Y.*; Yin, Z.*; Rong, Y.*; Tian, L.*; Liu, P.*; Wang, H.*; Xing, L.*; Wei, Y.*; et al.

npj Quantum Materials (Internet), 5(1), p.11_1 - 11_7, 2020/02

 被引用回数:4 パーセンタイル:33.97(Materials Science, Multidisciplinary)

We use neutron scattering to study Vanadium (hole)-doped LiFe$$_{1-x}$$V$$_{x}$$As. In the undoped state, LiFeAs exhibits superconductivity at $$T_mathrm{c} = 18$$ K and transverse incommensurate spin excitations similar to electron overdoped iron pnictides. Upon Vanadium doping to form LiFe$$_{0.955}$$V$$_{0.045}$$, the transverse incommensurate spin excitations in LiFeAs transform into longitudinally elongated ones in a similar fashion to that of potassium (hole)-doped Ba$$_{0.7}$$K$$_{0.3}$$Fe$$_{2}$$As$$_{2}$$ but with dramatically enhanced magnetic scattering and elimination of superconductivity. This is different from the suppression of the overall magnetic excitations in hole-doped BaFe$$_{2}$$As$$_{2}$$ and the enhancement of superconductivity near optimal hole doping. These results are consistent with density function theory plus dynamic mean field theory calculations, suggesting that Vanadium doping in LiFeAs may induce an enlarged effective magnetic moment $$S_mathrm{eff}$$ with a spin crossover ground state arising from the inter-orbital scattering of itinerant electrons.

論文

Uniaxial pressure effect on the magnetic ordered moment and transition temperatures in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ ($$T$$ = Co,Ni)

Tam, D. M.*; Song, Y.*; Man, H.*; Cheung, S. C.*; Yin, Z.*; Lu, X.*; Wang, W.*; Frandsen, B. A.*; Liu, L.*; Gong, Z.*; et al.

Physical Review B, 95(6), p.060505_1 - 060505_6, 2017/02

 被引用回数:24 パーセンタイル:68.89(Materials Science, Multidisciplinary)

We use neutron diffraction and muon spin relaxation to study the effect of in-plane uniaxial pressure on the antiferromagnetic (AF) orthorhombic phase in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ and its Co- and Ni-substituted members near optimal superconductivity. In the low-temperature AF ordered state, uniaxial pressure necessary to detwin the orthorhombic crystals also increases the magnetic ordered moment, reaching an 11% increase under 40 MPa for BaFe$$_{1.9}$$Co$$_{0.1}$$As$$_2$$, and a 15% increase for BaFe$$_{1.915}$$Ni$$_{0.085}$$As$$_2$$. We also observe an increase of the AF ordering temperature ($$T_N$$) of about 0.25 K/MPa in all compounds, consistent with density functional theory calculations that reveal better Fermi surface nesting for itinerant electrons under uniaxial pressure. The doping dependence of the magnetic ordered moment is captured by combining dynamical mean field theory with density functional theory, suggesting that the pressure-induced moment increase near optimal superconductivity is closely related to quantum fluctuations and the nearby electronic nematic phase.

論文

Nitrate facilitates cadmium uptake, transport and accumulation in the hyperaccumulator ${it Sedum plumbizincicola}$

Hu, P.*; 尹 永根; 石川 覚*; 鈴井 伸郎; 河地 有木; 藤巻 秀; 井倉 将人*; Yuan, C.*; Huang, J.*; Li, Z.*; et al.

Environmental Science and Pollution Research, 20(9), p.6306 - 6316, 2013/09

 被引用回数:57 パーセンタイル:79.83(Environmental Sciences)

${it Sedum plumbizincicola}$, a species in the family Crassulaceae, has been reported to be a Cd hyperaccumulator exhibiting fast growth, large biomass, asexual reproduction and perennial habit and showing remarkable potential in the phytoextraction of Cd from polluted soils. The aims of this study are to investigate whether and how the nitrogen form (nitrate (NO$$_{3}$$$$^{-}$$) versus ammonium (NH$$_{4}$$$$^{+}$$)) influences cadmium (Cd) uptake and translocation and subsequent Cd phytoextraction by the ${it S. plumbizincicola}$. This is the first report of successful visualisation and quantification of Cd uptake and root-to-shoot translocation in intact plants of the hyperaccumulator species ${it S. plumbizincicola}$ supplied with different forms of inorganic N using positron-emitting tracer imaging system (PETIS), a real-time imaging method.

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