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Multi-field Coupled Inverse Hall–Petch Relations for Ferroelectric Nanocrystals

Acta Mechanica Solida Sinica 2024年第1期37卷 139-147页

作者： Xiaodong Zhang Wei Yan Xuhui Lou Yujun Chen Zhihong Zhou Qingyuan Wang Lianhua Ma Xiaobao Tian non-destructive testing laboratory School of Quality and Technical SupervisionHebei UniversityBaoding 071002China AVIC Huiyang Aviation Propeller Co. LtdBaoding 071051China Department of Mechanics and Engineering Sichuan UniversityChengdu 610065China Yibin Institute of Industrial Technology Sichuan University Yibin ParkYibin 644000China Research Institute of Interdisciplinary Sciences(RISE) Dongguan University of TechnologyDongguan 523808China School of Materials Science and Engineering Dongguan University of TechnologyDongguan 523808China

Tailoring grain size can improve the strength of polycrystals by regulating the proportion of grains to grain boundaries and the interaction area.As the grain size decreases to the nanoscale,the deformation mechanism in polycrystals shifts from being primarily mediated by dislocations to deformation occurring within the grains and grain boundaries.However,the mechanism responsible for fine-grain strengthening in ferroelectric materials remains unclear,primarily due to the complex multi-field coupling effect arising from spontaneous polarization.Through molecular dynamics simulations,we investigate the strengthening mechanism of barium titanate(BaTiO3),with extremely fine-grain sizes.This material exhibits an inverse Hall–Petch relationship between grain size and strength,rooting in the inhomogeneous concentration of atomic strain and grain rotation.Furthermore,we present a theoretical model to predict the transition from the inverse Hall–Petch stage to the Hall–Petch stage based on strength variations with size,which aligns well with the simulation results.It has been found that the piezoelectric properties of the BaTiO3 are affected by polarization domain switching at various grain sizes.This study enhances our understanding of the atomic-scale mechanisms that contribute to the performance evolution of fine-grain nano-ferroelectric materials.It also provides valuable insights into the design of extremely small-scale ferroelectric components.

关键词： Ferroelectrics Multi-field coupling Molecular dynamics Fine-grain reinforcement Inverse Hall-Petch effect

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Tribological Behaviors of Electroless Nickel-Boron Coating on Titanium Alloy Surface

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 309-320页

作者： Yao Jia Jianping Lai Jiaxin Yu Huimin Qi Yafeng Zhang Hongtu He Key laboratory of testing Technology for Manufacturing Process in Ministry of Education State Key Laboratory of Environment-Friendly Energy MaterialsSouthwest University of Science and TechnologyMianyang 621010China

Titanium alloys are excellent structural materials in engineering fields,but their poor tribological properties limit their further applications.Electroless plating is an effective method to enhance the tribological performance of alloys,but it is difficult to efficiently apply to titanium alloys,due to titanium alloy’s strong chemical activity.In this work,the electroless Nickel-Boron(Ni-B)coating was successfully deposited on the surface of titanium alloy(Ti-6AL-4V)via a new pre-treatment process.Then,linearly reciprocating sliding wear tests were performed to evaluate the tribological behaviors of titanium alloy and its electroless Ni-B coatings.It was found that the Ni-B coatings can decrease the wear rate of the titanium alloy from 19.89×10^(−3)mm^(3)to 0.41×10^(−3)mm^(3),which attributes to the much higher hardness of Ni-B coatings.After heat treatment,the hardness of Ni-B coating further increases corresponding to coating crystallization and hard phase formation.However,heat treatment does not improve the tribological performance of Ni-B coating,due to the fact that higher brittleness and more severe oxidative wear exacerbate the damage of heat-treated coatings.Furthermore,the Ni-B coatings heat-treated both in air and nitrogen almost present the same tribological performance.The finding of this work on electroless coating would further extend the practical applications of titanium alloys in the engineering fields.

关键词： Electroless coating Titanium alloy Tribology Wear Heat treatment Nanoindentation

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Thermo-kinetic characteristics on stabilizing hetero-phase interface of metal matrix composites by crystal plasticity finite element method

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Journal of Materials Science & Technology 2024年第2期169卷 53-67页

作者： Y.B.Zhang S.J.Song F.Liu State Key laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Analytical&testing Center Northwestern Polytechnical UniversityXi’an 710072China

Using dislocation-based constitutive modeling in three-dimension crystal plasticity finite element(3D CPFE)simulations,co-deformation and instability of hetero-phase interface in different material systems were herein studied for polycrystalline metal matrix composites(MMCs).Local stress and strain fields in two types of 3layer MMCs such as fcc/fcc Cu-Ag and fcc/bcc Cu-Nb have been predicted under simple compressive deformations.Accordingly,more severe strain-induced interface instability can be observed in the fcc/bcc systems than in the fcc/fcc systems upon refining to metallic nanolayered composites(MNCs).By detailed analysis of stress and strain localization,it has been demonstrated that the interface instability is always accompanied by high-stress concentration,i.e.,thermodynamic characteristics,or high strain prevention i.e.,kinetic characteristics,at the hetero-phase interface.It then follows that the thermodynamic driving forceG and the kinetic energy barrier Q during dislocation and shear banding can be adopted to classify the deformation modes,following the so-called thermo-kinetic correlation.Then by inserting a high density of high-energy interfaces into the Cu-Nb composites,such thermo-kinetic integration at the hetero-phase interface allows a successful establishment of MMCs with the high△G-high Q deformation mode,which ensures high hardening and uniform strain distri-bution,thus efficiently suppressing the shear band,stabilizing the hetero-phase interface,and obtaining an exceptional combination in strength and ductility.Such hetero-phase interface chosen by a couple of thermodynamics and kinetics can be defined as breaking the thermo-kinetic correlation and has been proposed for artificially designing MNCs.

关键词： Thermodynamics and kinetics Physics-based constitutive modeling Hetero-phase interface Crystal plasticity finite element

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Corrosion behavior of HVOF Inconel 625 coating in the simulated marine environment

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China Welding 2024年第1期33卷 46-51页

作者：彭超钟丰平袁梦谢世杰王学斌 National Quality Inspection and testing Center of Special Metal Structural Materials Zhejiang Academy of Special Equipment ScienceHangzhou 310020China Key laboratory of Special Equipment Safety testing Technology of Zhejiang Province Hangzhou 310020China Zhejiang-Ukraine Joint laboratory for Materials and Welding testing Technology Hangzhou 310020China

High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy coatings.Inconel 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the surface and corrosion resistance properties of Inconel 625 HVOF coating.In this paper,potentiodynamic polarization tests and electrochemical impedance spectroscopy(EIS)tests were carried out to evaluate the corrosion resistance of Inconel 625 coating under simulated marine environment.The experiment-al results showed that Inconel 625 coating revealed low porosity and desired coating thickness.Shift in the corrosion potential(E_(corr))to-wards the noble direction combined with much low corrosion current density(i_(corr))indicating a significant improvement of HVOF Inconel 625 coating compared with the substrate.

关键词： high velocity oxygen fuel(HVOF) Inconel 625 coating marine environment corrosion

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Effect of hot isostatic pressure on the microstructure and tensile properties of γ'-strengthened superalloy fabricated through induction-assisted directed energy deposition

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1089-1097页

作者： Jianjun Xu Hanlin Ding Xin Lin Feng Liu Analytical&testing Center Northwestern Polytechnical UniversityXi’an 710072China State Key laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples subjected to IDED under 1050℃ preheating with and without hot isostatic pressing(HIP,1190℃,105 MPa,and 3 h).Results show that the as-deposited sample mainly consisted of epitaxial columnar crystals and inhomogeneously distributed γ’ phases in interdendritic and dendritic core regions.After HIP,grain morphology changed negligibly,whereas the size of the γ’ phase became increasingly even.After further heat treatment(HT,1070℃,2 h + 845℃,24 h),the γ’ phase in the as-deposited and HIPed samples presented a bimodal size distribution,whereas that in the as-deposited sample showed a size that remained uneven.The comparison of tensile properties revealed that the tensile strength and uniform elongation of the HIP + HTed sample increased by 5% and 46%,respectively,due to the synergistic deformation of bimodal γ’phases,especially large cubic γ’ phases.Finally,the relationship between phase transformations and plastic deformations in the IDEDed sample was discussed on the basis of generalized stability theory in terms of the trade-off between thermodynamics and kinetics.

关键词： directed energy deposition Ni-based superalloys high-temperature preheating hot isostatic pressing microstructure tensile properties

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Dynamic manipulation of multimodal emission in Er3+-activated non-core-shell structure for optical thermometry and information security

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Rare Metals 2024年第4期43卷 1702-1712页

作者： Xuan Liu Zi-Xia Lin Yin-Biao Shi Xiao-Yan Wang Ming-Ye Ding Xiao-Fei Yang College of Science Nanjing Forestry University testing Center Yangzhou University

Regulating luminescent dynamics of lanthanide-based luminescent materials via external stimuli is of great significance in the fields of optical thermometry and high-level anti-counterfeiting.However,it is still a huge challenge to realize multimodal emissions with tunable color outputs from a single activator in simple structures via smart dynamic control of photon transition processes.Herein,we present a mechanistic strategy to achieve multimodal luminescence of Er3+activators with color-switchable outputs in a non-core-shell host.Under the control of excitation dynamics(λex=980,808,1532,377 nm),the population among the intermediate en ergy levels of Er3+and the interaction between Er3+and Yb3+could be precisely modulated through energy transfer and migration processes,leading to the generation of colortunable multimodal luminescence upon diverse excitation modes（non-steady-state,single-/dual-wavelength steady,thermal activation）.Inspired by its special luminescent performance,the as-obtained material exhibits great potential in noncontact thermometry,multimodal anticounterfeiting,and high-capacity information encryption by performing a series of proof-of-concept experiments.Our findings might provide a conceptual model to modulate the luminescent dynamics in a simple-structured system for the generation of color-adjustable multimodal emissions,which is convenient for the development of advanced luminescent materials toward versatile cuttingedge applications.

关键词： Lanthanide ions Multimodal emission Upconversion Downshifting Anti-counterfeiting Luminescent thermometry

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Application of the CatBoost Model for Stirred Reactor State Monitoring Based on Vibration Signals

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 647-663页

作者： Xukai Ren Huanwei Yu Xianfeng Chen Yantong Tang Guobiao Wang Xiyong Du School of Mechanical Engineering Tianjin UniversityTianjin300354China Quality Department Shaoxing Key Laboratory of Special Equipment Intelligent Testing and EvaluationShaoxing312071China

Stirred reactors are key equipment in production,and unpredictable failures will result in significant economic losses and safety issues.Therefore,it is necessary to monitor its health state.To achieve this goal,in this study,five states of the stirred reactor were firstly preset:normal,shaft bending,blade eccentricity,bearing wear,and bolt looseness.Vibration signals along x,y and z axes were collected and analyzed in both the time domain and frequency domain.Secondly,93 statistical features were extracted and evaluated by ReliefF,Maximal Information Coefficient(MIC)and XGBoost.The above evaluation results were then fused by D-S evidence theory to extract the final 16 features that are most relevant to the state of the stirred reactor.Finally,the CatBoost algorithm was introduced to establish the stirred reactor health monitoring model.The validation results showed that the model achieves 100%accuracy in detecting the fault/normal state of the stirred reactor and 98%accuracy in diagnosing the type of fault.

关键词： Stirred reactor fault diagnosis vibration signal CatBoost

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Nanocrystalline WSe_(2)excels at high-performance anode for Na storage via a facile one-pot hydrothermal method

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Tungsten 2024年第1期6卷 248-258页

作者： Hai-Yan Zou Lei Fang Gang Yu Dong Wang State Key laboratory of Chem/Bio-Sensing and Chemometrics Provincial Hunan Key Laboratory for Graphene Materials and DevicesCollege of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China Changxing County Quality and Technology Supervision and testing Center Huzhou 313100China

For the next large-scale energy storage systems,sodium-ion batteries(SIBs)with excellent electrochemical performance are promising.However,the exploration of anode materials with high specific capacity,fascinating cycling stability and rate capability is still restricted.Among transition metal dichalcogenides(TMDs),tungsten diselenide(WSe_(2))has been regarded as an effective anode material for SIBs and has been extensively studied,due to high theoretical capacity and unique twodimensional layered structure.Herein,nanocrystalline WSe_(2)is prepared by a facile one-pot hydrothermal method.Compared with the micro-scale WSe_(2),benefiting from the high specific surface area of highly ordered nano-flake structures and short ion/electron transport paths,nanocrystalline WSe_(2)shows excellent electrochemical performance in Na storage.After 1000 cycles at a current density of 2 A·g^(-1),a high specific capacity of 264.4 mA·h·g^(-1)is still maintained.The full cell matched with the Na_(3)V_(2)(PO_(4))_(3) cathode can deliver an excellent reversible specific capacity of 196.5 mA·h·g^(-1)after 100 cycles at 0.5 A·g^(-1).

关键词： Tungsten diselenide Transition metal dichalcogenides Hydrothermal Sodium-ion batteries Layered structure

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Flotation separation of scheelite from calcite using luteolin as a novel depressant

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International Journal of Minerals,Metallurgy and Materials 2024年第3期31卷 462-472页

作者： Xiaokang Li Ying Zhang Haiyang He Yu Wu Danyu Wu Zhenhao Guan Faculty of Land and Resources Engineering Kunming University of Science and TechnologyKunming 650093China State Key laboratory of Clean Utilization of Complex non-Ferrous Metal Resources Kunming University of Science and TechnologyKunming 650093China

This paper proposes luteolin(LUT)as a novel depressant for the flotation-based separation of scheelite and calcite in a sodium oleate(NaOL)system.The suitability of LUT as a calcite depressant is confirmed through micro-flotation testing.At pH=9,with LUT concentration of 50 mg·L^(-1) and NaOL concentration of 50 mg·L^(-1),scheelite recovery reaches 80.3%.Calcite,on the other hand,exhibits a recovery rate of 17.6%,indicating a significant difference in floatability between the two minerals.Subsequently,the surface modifica-tions of scheelite and calcite following LUT treatment are characterized using adsorption capacity testing,Zeta potential analysis,Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),and atomic force microscopy(AFM).The study in-vestigates the selective depressant mechanism of LUT on calcite.Adsorption capacity testing and Zeta potential analysis demonstrate sub-stantial absorption of LUT on the surface of calcite,impeding the further adsorption of sodium oleate,while its impact on scheelite is min-imal.FT-IR and XPS analyses reveal the selective adsorption of LUT onto the surface of calcite,forming strong chemisorption bonds between the hydroxyl group and calcium ions present.AFM directly illustrates the distinct adsorption densities of LUT on the two miner-al types.Consequently,LUT can effectively serve as a depressant for calcite,enabling the successful separation of scheelite and calcite.

关键词： scheelite calcite luteolin flotation depressant separation

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Laser powder bed fusion of NiTiFe shape memory alloy via premixed powder: microstructural evolution, mechanical and functional properties

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Rare Metals 2024年第5期43卷 2300-2316页

作者： Bo Yuan Jin-Guo Ge Liang Zhang Hong-Jun Chen Long-Sha Wei Yu-Duo Zhou Run-Hua Song Institute of Intelligent Manufacturing Technology Shenzhen Polytechnic School of Mechanical and Electrical Engineering Guilin University of Electronic Technology Guangdong Advanced Polymer Composite EngineeringTechnology Research Center Shenzhen Academy of Aerospace Technology Jihua laboratory testing Center Jihua Laboratory

High-cost pre-alloyed powder is the bottleneck problem that limits the widespread application of additivemanufactured shape memory alloys. In this work, the lowcost ternary NiTiFe shape memory alloy is fabricated by laser powder bed fusion (LPBF) technique via mechanically mixed pre-alloy NiTi powder and varying contents pure Fe powder (1, 2, 3 wt%). All NiTiFe alloys show a relative density of up to 99.8%by optimizing the LPBF processing parameters. Owing to the heterogeneous nucleation effect of micron-sized Fe particles, both grain refinement and texture weakening are generated in the NiTiFe alloys, accompanied by the reduction of dislocation density. For the room-temperature mechanical properties,the NiTi-3Fe alloy shows the highest microhardness of HV370, but the fracture strength and elongation reduce to1701 MPa and 23%simultaneously. The evolution of mechanical properties is attributed to the high internal defects, low dislocation density and the incoherent oxide.Moreover, the NiTi-3Fe alloy shows the quasi-linear superelasticity behavior; the superelastic recoverable strain of NiTi-1Fe and NiTi-2Fe decreased with the increase in Fe content. This study provided a new-fangled insight for the development of multi-component NiTi-based shape memory alloys by additive manufacturing.

关键词： Additive manufacturing Shape memory alloy Metal matrix composite Microstructure Mechanical properties

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