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Chinese Journal of Aeronautics 2022年第1期35卷 137-143页

作者： Meini YUAN zhijun wang Fangzhou HAN College of Mechatronic Engineering North University of ChinaTaiyuan 030051China

For metal-intermetallic laminated composites,various types of defects often occur during the preparation *** paper studied the evolution and formation mechanism of defects,such as pores,tunnel cracks,and delamination cracks in Ti-Al_(3)Ti laminated composites prepared by vacuum hot-pressing ***,quasi-static and dynamic compression tests were performed to study the effects of pores and delamination cracks on the compression properties of the *** results showed that for Ti-Al_(3)Ti laminated composites prepared at 710℃,their Al_(3)Ti layers exhibit a porous structure,and the porosity of Al_(3)Ti layers firstly decreases and then increases under the combined action of press,the self-propagating reaction and Al3Ti grain *** tunnel cracks in Ti-Al_(3)Ti laminated composites are resulted by tensile residual stresses and the inherent brittleness of *** Ti-Al_(3)Ti laminated composites prepared at 680°C,the formation of delamination cracks is mainly related to the diffuse reaction of Ti/Al atoms and the Kirkendall effect,and the numbers of delamination cracks increase with the increasing of sintering ***,the pores and delamination cracks greatly deteriorate the compression properties of Ti-Al_(3)Ti laminated ***-free and dense Ti-Al_(3)Ti laminated composites exhibit the highest compression properties.

关键词： Compression strength Cracks Diffusion coefficients Laminated composites Scanning electron microscopy

On Ti6Al4V Microsegregation in Electron Beam Additive Manufacturing with Multiphase-Field Simulation Coupled with Thermodynamic Data

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 425-438页

作者： Yujian wang Shuo Chu zhijun wang Junjie Li Jincheng wang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

Electron beam additive manufacturing is an effective method for the fabrication of complex metallic *** rapid solidification,the characteristics of microsegregation within the interdendritic region are interesting and important for the subsequent phase transformation and final mechanical ***,in view of the microsecond lifetime and the small length scale of the molten pool,experimentally investigating microsegregation is challenging,even with electron probe *** this study,a multiphase-field model coupled with the real thermodynamic data of Ti6Al4V alloy was successfully developed and applied to simulate the rapid solidification of columnarβgrains via electron beam additive *** thermal gradient(G)and cooling rate(R)were obtained from a 3D powder-scale multiphysics simulation and provided as inputs to a multiphase-field *** eff ects of the electron beam process parameters and thermal conditions on the columnarβgrains were *** films and droplets were observed to have solute enrichment in the intercellular *** size of the liquid film increased at a lower scanning speed and energy *** the scanning speed and energy power refined the columnarβgrains and decreased the liquid film *** extent of microsegregation considerably increased at lower energy power,whereas the change in scanning speed had little eff ect on the *** results also indicate that solute vanadium results in significant solute trapping and microsegregation during the rapid solidification of the Ti6Al4V alloy.

关键词： Ti6Al4V alloy Microsegregation Electron beam additive manufacturing Multiphase-field model

Erosion Behavior of NiCoCrFeNb_(0.45) Eutectic High-Entropy Alloy in Liquid-Solid Two-Phase Flow

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Acta Metallurgica Sinica(English Letters) 2022年第8期35卷 1266-1274页

作者： Kai wang Zhenjiang wang Jinling Lu zhijun wang Wei wang Xingqi Luo State Key Laboratory of Eco-Hydraulics in Northwest Arid Region Xi'an University of TechnologyXi'an 710048China State Key Laboratory of Solidification Procesing Northwestern Polytechnical UniversityXi'an 710072China

The metal components exposed to the high-velocity liquid-solid flow can be rapidly eroded by the accelerated *** an excellent combination of strength and toughness,the NiCoCrFeNb_(0.45)eutectic high-entropy alloy(EHEA)has emerged as a promising material to resist erosion *** this study,the erosion behavior of NiCoCrFeNb_(0.45)EHEA in high-velocity multiphase flow is investigated through the coupling analysis of material properties,multiphase flow,and particle–surface impact *** inherent mathematical relationship is discovered between the erosion rates and the impact velocity,impact angle,and test *** results show that the NiCoCrFeNb_(0.45)EHEA has superior erosion resistance than the commonly used machinery *** principal material removal mechanism is the formation and brittle fracture of the platelets,accompanied by micro-cutting and ploughing at some oblique *** higher work-hardenability of NiCoCrFeNb_(0.45)EHEA could mitigate the erosion damage as time proceeds,and this effect becomes more apparent as the impact angle ***,the evolution of erosion damage with time varies significantly depending on the impact *** on the test data and computational fluid dynamics(CFD)modeling of the near-wall flow field,a power exponential function relationship between erosion depth and the corresponding impact velocity at various locations on the material surface is established.

关键词： Eutectic high-entropy alloy Erosion evolution Multiphase flow Computational fluid dynamics(CFD)modeling

Superior Slurry Erosion Behavior of a Casting NiCoCrFeNb0.45 Eutectic High Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2020年第8期33卷 1111-1116页

作者： Jinling Lu Zhenjiang wang Wei wang Kexuan Zhou Feng He zhijun wang Faculty of Water Resources and Hydroelectric Engineering Xi’an University of TechnologyXi'an 710048China State Key Laboratory of Solidifi cation Processing Northwestern Polytechnical UniversityXi'an 710072China

The flow passage components in hydraulic machinery will be eroded rapidly when running in sand *** wear resistance of materials commonly used in hydraulic machinery needs to be improved to prevent the failure of hydraulic *** wear-resistant materials are urgently needed to improve the service life of hydraulic *** high entropy alloy(EHEA)is a new kind of alloys with in situ lamellar ***0.45 EHEA has combined excellent strength and *** this study,slurry erosion tests of NiCoCrFeNb0.45 EHEA were carried out with different impact angles and impact velocities using a rotary jet erosion test *** NiCoCrFeNb0.45EHEA exhibited significant slurry erosion resistance compared with medium carbon steel 1045 and stainless steel 04 Cr13 Ni5 *** erosion rate of EHEA is much *** with medium carbon steel and stainless steel,the erosion of EHEA is completed via the accumulation and removal of platelets after plowing and work hardening,accompanied by partial micro-cutting.

关键词： Eutectic high entropy alloy Friction and wear Slurry erosion

Hinge Majorana flat band in type-Ⅱ Dirac semimetals

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 127-132页

作者： Yue Xie Xianxin Wu Zhong Fang zhijun wang Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing100190China

Type-Ⅱ Dirac semimetals exhibit a unique Fermi surface topology,which allows them to host novel topological superconductivity(TSC).We reveal a novel inter-orbital superconducting state,corresponding to the B_(1u) and B_(2u) pairings under the D_(4h) point ***,we find that both first-and second-order TSC coexist in this novel *** is induced by a dominant inter-orbital attraction and possesses surface helical Majorana cones and hinge Majorana flat bands,spanning the entire z-directed hinge Brillouin *** investigation uncovers that these higher-order hinge modes are robust against the C_(4z) symmetry-breaking perturbation.

关键词： topological superconductivity Majorana fermions higher-order topology type-II Dirac semimetals

Endless recrystallization of high-entropy alloys at high temperature

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Journal of Materials Science & Technology 2022年第33期128卷 71-81页

作者： Qingfeng Wu zhijun wang Feng He Zhongsheng Yang Junjie Li Jincheng wang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

In traditional physical metallurgy,once recrystallization occurs,it will proceed to 100%along with time even at relatively low temperatures,resulting in the limited thermal stability of partially recrystallized ***,we proposed the strategy of achieving the endless recrystallization state at high temperature(~0.6T_(m))in high entropy alloys for the first *** partially recrystallized microstructures remained stable after annealing at 700℃ for 1440 h toward endless recrystallization with kinetics *** from the ultra-thermostable heterostructures,the alloy exhibited excellent mechanical properties of~1.6 GPa tensile strength at room temperature and~1.1 GPa tensile strength at 600°C even after exposure at 700℃ for 720 *** kinetics of recovery,recrystallization,grain growth,and precipitate coarsening were quantitatively analyzed to uncover the mechanisms of endless *** results revealed that the stable state of 50%recrystallization at 700℃ can be attributed to the precipitates inhibited recrystallization and the continued recovery decreased stored energy in the non-recrystallized ***,the grain size was stable in the recrystallized regions due to the strong pinning effect of the intergranular precipitates with slow coarsening *** findings created a brand-new state of endless recrystallization with the combination of recovery and recrystallization,which can significantly broaden the service temperature range of heterogeneous materials.

关键词： Endless recrystallization High-entropy alloy Partial recrystallization Thermal stability High-temperature mechanical properties

m^(6)A demethylase FTO regulate CTNNB1 to promote adipogenesis of chicken preadipocyte

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Journal of Animal Science and Biotechnology 2023年第2期14卷 578-592页

作者： Kan Li Weichen Huang zhijun wang Qinghua Nie Department of Animal Genetics Breeding and ReproductionCollege of Animal ScienceSouth China Agricultural UniversityGuangzhou 510642China National‑Local Joint Engineering Research Center for Livestock Breeding Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breedingand Key Laboratory of Chicken GeneticsBreeding and ReproductionMinistry of AgricultureGuangzhou 510642China

Background:N6-methyladenosine(m^(6)A)is an abundant post-transcriptional RNA modification that affects various biological *** fat mass and obesity-associated(FTO)protein,a demethylase encoded by the FTO gene,has been found to regulate adipocyte development in an m^(6)A-dependent manner in multiple ***,the effects of the m^(6)A methylation and FTO demethylation functions on chicken adipogenesis remain *** study aims to explore the association between m^(6)A modification and chicken adipogenesis and the underlying mechanism by which FTO affects chicken preadipocyte ***:The association between m^(6)A modification and chicken lipogenesis was assessed by treating chicken pread-ipocytes with different doses of methyl donor betaine and methylation inhibitor *** results showed that betaine significantly increased methylation levels and inhibited lipogenesis,and the inverse effect was found in preadipocytes after cycloleucine *** of FTO significantly inhibited m^(6)A levels and promoted proliferation and differentiation of chicken *** FTO showed opposite ***,FTO overexpression increased the expression of catenin beta 1(CTNNB1)by improving RNA stability in an m^(6)A-dependent manner,and we proved that FTO could directly target ***,CTNNB1 may be a positive regulator of adipogenesis in chicken ***:m^(6)A methylation of RNA was negatively associated with adipogenesis of chicken *** could regulate CTNNB1 expression in a demethylation manner to promote lipogenesis.

关键词： Adipogenesis Chicken CTNNB1 FTO m^(6)A

Electronic structures and topological properties in nickelates Lnn+1Ni_nO2n+2

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National Science Review 2021年第8期8卷 208-215页

作者： Jiacheng Gao Shiyu Peng zhijun wang Chen Fang Hongming Weng Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences Songshan Lake Materials Laboratory Kavli Institute for Theoretical Sciences Chinese Academy of Sciences Physical Science Laboratory Huairou National Comprehensive Science Center

After the significant discovery of the hole-doped nickelate compound Nd0.8Sr0.2NiO2, analyses of the electronic structure, orbital components, Fermi surfaces and band topology could be helpful to understand the mechanism of its superconductivity. Based on first-principle calculations, we find that Ni3dx2-y2states contribute the largest Fermi surface. The Ln5d3z2-r2states form an electron pocket at, while 5 dxy states form a relatively bigger electron pocket at A. These Fermi surfaces and symmetry characteristics can be reproduced by our two-band model, which consists of two elementary band representations: B1g@1a⊕A1g@1b. We find that there is a band inversion near A, giving rise to a pair of Dirac points along M-A below the Fermi level upon including spin-orbit coupling. Furthermore,we perform density functional theory based Gutzwiller（DFT+Gutzwiller） calculations to treat the strong correlation effect of Ni 3 d orbitals. In particular, the bandwidth of 3dx2-y2has been renormalized *** the renormalization of the correlated bands, the Ni 3 dxy states and the Dirac points become very close to the Fermi level. Thus, a hole pocket at A could be introduced by hole doping, which may be related to the observed sign change of the Hall coefficient. By introducing an additional Ni3dxyorbital, the hole-pocket band and the band inversion can be captured in our modified model. Besides, the nontrivial band topology in the ferromagnetic two-layer compound La3Ni2O6is discussed and the band inversion is associated with Ni3dx2-y2and La5dxyorbitals.

关键词： nickelate superconductors band representations topological Dirac points DFT+Gutzwiller calculations

The intrinsic mechanism of corrosion resistance for FCC high entropy alloys

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Science China(Technological Sciences) 2018年第2期61卷 189-196页

作者： shang xuliang wang zhijun he feng wang jincheng li junjie yu jiakang state key laboratory of solidification processing northwestern polytechnical universityXi’an 710072China

The concept of high entropy alloys(HEAs) or multi-principal component alloys has inspired a great progress of physical metallurgy along with several unusual phenomena. The high corrosion resistance of HEAs was frequently mentioned but without convincing explanations. In this paper, the intrinsic mechanism of corrosion resistance in FCC HEAs was revealed by designing equal atomic alloys with single solid solution phase. The results showed that the Cr element in FCC HEAs played the dominant role in the corrosion resistance rather than the simple structure from high entropy effect or uniform element distribution.

关键词： high entropy alloys corrosion resistance chromium

A Game Theoretic Approach for Inter-Network Interference Mitigation in Wireless Body Area Networks

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China Communications 2015年第9期12卷 150-161页

作者： Du Dakun Hu Fengye wang Feng wang zhijun Du Yu wang Lu College of Communication Engineering Jilin University

Wireless Body Area Network(WBAN) is an emerging technology to provide real-time health monitoring and ubiquitous healthcare services. In many applications, multiple wireless body area networks have to coexist in a small area, resulting in serious inter-network interference. This not only reduces network reliability that is especially important in emergency medical applications, but also consumes more power of WBANs. In this paper, an inter-network interference mitigation approach based on a power control algorithm is proposed. Power control is modeled as a non-cooperative game, in which both inter-network interference and energy efficiency of WBANs are considered. The existence and uniqueness of Nash Equilibrium in the game are proved, and an optimal scheme based on best response is proposed to find its Nash Equilibrium. By coordinating the transmission power levels among networks under interference environment, the total system throughput can be increased with minimum power consumed. The effectiveness of the proposed method has been illustrated by simulation results, where the performance of the proposed approach is evaluated in terms of overall utility and power efficiency and convergence speed.

关键词： wireless body area network power control inter-network interference game theory