The BCC 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

https://doi.org/10.1016/j.msea.2024.146096

The quasi-static superelastic responses and hierarchical martensite transformation from body-centered cubic (BCC) to face-centered cubic (FCC) under dynamic impact in FeMnAlNiTi 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 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.

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

https://doi.org/10.1038/s41535-020-0212-x

We use neutron scattering to study Vanadium (hole)-doped LiFeVAs. In the undoped state, LiFeAs exhibits superconductivity at K and transverse incommensurate spin excitations similar to electron overdoped iron pnictides. Upon Vanadium doping to form LiFeV, the transverse incommensurate spin excitations in LiFeAs transform into longitudinally elongated ones in a similar fashion to that of potassium (hole)-doped BaKFeAs but with dramatically enhanced magnetic scattering and elimination of superconductivity. This is different from the suppression of the overall magnetic excitations in hole-doped BaFeAs 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 with a spin crossover ground state arising from the inter-orbital scattering of itinerant electrons.

Observation of and search for at = 10.96 - 11.05 GeV

Yin, J. H.*; 谷田 聖; Belle Collaboration*; 他189名*

Physical Review D, 98(9), p.091102_1 - 091102_9, 2018/11

AA2018-0718.pdf:0.5MB

https://doi.org/10.1103/PhysRevD.98.091102

We report searches for the processes and (J=1,2) in the vicinity of the resonance using energy scan data collected by the Belle experiment at the KEKB collider. We observe and find evidence for processes for data with center-of-mass energies from 10.96 to 11.05~GeV for the first time. The statistical significance for and are and , respectively. We investigate energy dependence of the cross section and find that it is consistent with production of and resonances without significant non-resonant contribution. Assuming proceeds via and , the branching fraction is measured for the first time, where the first error is statistical, the second is systematic, and the third from the branching fraction of . The signals for are not significant, and the upper limits of the Born cross sections at the 90% confidence level are and ~pb for and , respectively, for center-of-mass energies from 10.96 to 11.05 GeV.

Uniaxial pressure effect on the magnetic ordered moment and transition temperatures in BaFeTAs ( = 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

https://doi.org/10.1103/PhysRevB.95.060505

We use neutron diffraction and muon spin relaxation to study the effect of in-plane uniaxial pressure on the antiferromagnetic (AF) orthorhombic phase in BaFeTAs 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 BaFeCoAs, and a 15% increase for BaFeNiAs. We also observe an increase of the AF ordering temperature () 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.

From laboratory to field; -knockdown rice is a promising candidate for Cd phytoremediation in paddy fields

高橋 竜一*; 石丸 泰寛*; Shimo, H.*; Bashir, K.*; 瀬野浦 武志*; 杉本 和彦*; 小野 和子*; 鈴井 伸郎; 河地 有木; 石井 里美; et al.

PLOS ONE (Internet), 9(6), p.e98816_1 - e98816_7, 2014/06

https://doi.org/10.1371/journal.pone.0098816

Previously, we reported that OsNRAMP5 functions as a manganese, iron, and cadmium (Cd) transporter. The shoot Cd content in RNAi plants was higher than that in wild-type (WT) plants, whereas the total Cd content (roots plus shoots) was lower. For efficient Cd phytoremediation, we produced RNAi plants using the natural high Cd-accumulating cultivar Anjana Dhan (A5i). Using a positron-emitting tracer imaging system, we assessed the time-course of Cd absorption and accumulation in A5i plants. Enhanced Cd translocation from the roots to the shoots was observed in A5i plants. To evaluate the phytoremediation capability of A5i plants, we performed a field experiment in a Cd-contaminated paddy field. The biomass of the A5i plants was unchanged by the suppression of expression; the A5i plants accumulated twice as much Cd in their shoots as WT plants. Thus, A5i plants could be used for rapid Cd extraction and the efficient phytoremediation of Cd from paddy fields, leading to safer food production.

Combination of N and N isotope methods for the estimation of fixation and early distribution of nitrogen in soybean

石井 里美; Nguyen Van Phi, H.*; 鈴井 伸郎; 河地 有木; 尹 永根; 大山 卓爾*; 藤巻 秀

no journal, , 

Various methods are used in the field of biological nitrogen fixation. In this study, we analyzed early dynamics of nitrogen fixation and subsequent transport in soybean by using radioactive and stable isotopes, N and N. N has an advantage for the analysis of kinetics and visualization, while N is beneficial for the analysis of distribution. N is the only practical radioisotope of nitrogen which has a very short half-life of only 9.97 min. In this study, we improved a rapid method to produce N with higher radioactivity and sufficient purity. We fed the tracer gas to the underground part of soybean plants for 10 min and collected the serial images for one hour by PETIS. As a result, we finally obtained the image of transport to the aerial part successfully. The stable isotope N has been widely used for the analysis of fixation and export. In this study, we fed N to the underground part of soybean plants for one hour and analyzed the time course of the distribution in the whole body. As a result, we found that about 10% of fixed nitrogen was exported from the root nodules in the initial one hour. From a methodological aspect, we concluded that the combination of N and N isotope is a strong tool for quantitative analysis of fixation and transport of nitrogen.