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Journal of Materials Science & Technology 2022年第5期100卷 246-253页

作者： J.F.Zhao H.P.Wang B.Wei School of Physical Science and Technology Northwestern Polytechnical UniversityXi’an 710072China

A new intermetallic compound of thermodynamically stable Nb_(2)Ni phase is discovered within Nb-Ni binary system,refreshing the current situation that there are only three stable intermediate phases of Nb_(7)Ni_(6),NbNi_(3) and NbNi_(8).The new stable phase is generated from the peritectoid transition:(Nb)+Nb_(7)Ni_(6)→Nb_(2)Ni,and the transformation temperature is 1533 K.This refreshes the current equilibrium Nb-Ni binary phase diagram.It is confirmed by transmission electron microscopy and the annealing experiments,which is determined to be the FCC structure(Pearson:cF96,space grope:Fd-3m O2,a=11.888A).Furthermore,the equilibrium properties of Nb_(2)Ni phase are produced by density functional theory,including the formation energy,cohesive energy,bulk modulus and lattice constant.

关键词： Intermetallic compound Peritectoid transition Transmission electron microscopy Density functional theory Nb alloy

Nano-phase transformation of composite precipitates in multicomponent Al-Mg-Si(-Sc)alloys

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Journal of Materials Science & Technology 2022年第15期110卷 216-226页

作者： S.b.Wang C.F.Pan B.Wei X.Zheng Y.X.Lai J.H.Chen Key Laboratory of LCR Materials and Devices of Yunnan Province National Center for International Research on Photoelectric and Energy MaterialsSchool of Materials and EnergyYunnan UniversityKunming 650091China Collaborative Innovation Center of Renewable Energy Materials and Department of Physics Guangxi UniversityNanning 530004China Center for High-Resolution Electron Microscopy College of Materials Science and EngineeringHunan UniversityChangsha 410082China

Sc-addition can significantly enhance the performance of the micro-alloyed Al-Mg-Si-Sc alloys.However,the mechanisms by which the Sc element modifies the microstructure of the alloys are still unknown in many cases.Here,using atomic-scale transmission electron microscopy and atomic-resolution spectroscopy,we have revealed the microstructural differences between two age-hardened Al-0.5Mg-0.4Si(wt.%)alloys with and without Sc-addition.The first significant effect of Sc-addition on the precipitation microstructure of the Al-Mg-Si-Sc alloy is that Sc-atoms may distribute at theβ"-precipitate/Al-matrix interface and therefore accelerate aging kinetics at the initial stage of hardening.The second significant effect of Sc-addition is that in the transition from theβ"-hardened peak-age stage to theβ′-hardened late stage,Sc-atoms can greatly improve the stability of transitionalβ"/b'/β′composite precipitates by entering the b'-substructures and/or locating at the precipitate/Al interfaces.As such Sc-atoms effectively suppressβ"toβ'transformation and cross-sectional coarsening of bothβ"and composite precipitates,leading to much finer precipitate needles with smaller diameter but much larger length,as compared with those precipitate needles formed in the alloy without Sc-addition.Hence,the alloy with Sc-addition exhibits a much better thermal stability than that without Sc.

关键词： Al alloy Strengthening mechanism Phase transition Transmission electron microscopy

Ultrasonic solidification mechanism and optimized application performances of ternary Mg_(71.5)Zn_(26.1)Y_(2.4) alloy

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Journal of Magnesium and Alloys 2023年第10期11卷 3829-3839页

作者： Y.J.Hu J.Y.Wang W.Zhai B.Wei School of Physical Science and Technology Northwestern Polytechnical UniversityXi’an 710072China

One dimensional(1D) and three dimensional(3D) ultrasound sources were applied to the solidification process of Mg_(71.5)Zn_(26.1)Y_(2.4) alloy.The acoustic spectra were in-situ measured, based on which the cavitation intensities and dynamic solidification mechanism were further investigated. With the increase of ultrasonic dimension and amplitude, the primary Mg_(3)Zn_(6)Y phase was significantly refined from petals to nearly pentagonal shape. The sound field measurements showed that the transient cavitation played a decisive role in generating a high local undercooling, which facilitated the formation of icosahedral clusters and promoted the nucleation of primary Mg_(3)Zn_(6)Y phase. The morphological transition of(α-Mg+Mg_(3)Zn_(6)Y) eutectic from lamellar to anomalous structure occurred under 3D ultrasonic condition. The stable cavitation took the main responsibility because the high pressure excited by nonlinearly oscillating bubbles induced the preferential nucleation of α-Mg phase rather than Mg_(3)Zn_(6)Y phase. As compared with its static values, the tensile strength and compression plasticity of this alloy were increased by the factors of 1.9 and 2.1, and its corrosion resistance was also improved with the corrosion current density decreased by one order of magnitude.

关键词： Three dimensional ultrasounds Quasicrystalline Mg_(3)Zn_(6)Y phase Anomalous eutectic Mechanical performances Corrosion resistance

Ultrasonic excitation induced nanocrystallization and toughening of Zr46.75Cu46.75Al6.5 bulk metallic glass

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Journal of Materials Science & Technology 2020年第10期42卷 157-161页

作者： W.Zhai L.H.Nie X.D.Hui Y.Xiao T.Wang B.Wei School of Physical Science and Technology Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory for Advanced Metals and Materials University of Science&Technology BeijingBeijing 100083China

Intensive power ultrasound is introduced to Zr46.75Cu46.75Al6.5bulk metallic glass(bMG)as an easy-procurable,non-destructive physical method to modulate its atomic rearrangement and shear deformation behavior.The microstructure after ultrasonic excitation with amplitude about 15μm in 20 k Hz for 2 h is characterized by large amount of Cu10Zr7 nanocrystals with size of 20–50 nm embedded in the glass matrix.This leads to a sharp increase in the critical stress for the first pop-in event of shear banding,and thus simultaneously improves both compressive plasticity and yield strength.Our findings provide a novel approach for overcoming the strength-ductility trade-off dilemma.

关键词： bulk metallic glass Nanocrystallization Plasticity Toughness Ultrasound

Density determination and simulation of Inconel 718 alloy at normal and metastable liquid states

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Journal of Materials Science & Technology 2018年第3期34卷 436-439页

作者： H.P.Wang C.H.Zheng P.F.Zou S.J.Yang L.Hu B.Wei Department of Applied Physics Northwestern Polytechnical University

The density of liquid Incone1718 alloy was experimentally measured by electrostatic levitation technique, where the maximum undercooling of 100 K was realized for the commercial sample. The measured density of liquid lnconel 718 alloy is 7.39 g cm^-3 at the liquidus temperature of 1663 K which was confirmed by DSC experiment, with the linear temperature coefficient of -6.89 × 10^-4 gcm^-3 K^-1. Correspondingly, four ternary Ni-Cr-Fe compositions were designed to simulate the density of liquid lnconel 718 alloy with 16000 atoms, from which the liquid structure is revealed by pair distribution function, The predicted result shows a remarkable enhancement with the decrease of temperature at the first neighbor distance.

关键词： Undercooling Density Liquid metal and alloy Levitation

Theoretical study of ion-molecule collision: dynamics, cross sections, and dissociation

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Theoretical study of ion-molecule collision: dynamics, cross...

第七届全国计算原子与分子物理学术会议

作者： W.Yu C.-Z.Gao Y.Wu B.Wei Institute of Modern Physics Fudan University Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) Fudan University Institute of Applied Physics and Computational Mathematics

＜正＞Using time-dependent density-functional theory coupled non-adiabatically to molecular dynamics（TDDFT-MD）,we investigate the scattering dynamics,cross sections and dissociation in ion-induced collision.The electronic evolution is described by Kohn-Sham equations and ionic dynamics is treated on the level of classical molecule dynamics according to Ehrenfest theorem.

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等离子喷涂陶瓷颗粒的扁平化转变机制

热喷涂技术 2017年第1期9卷 41-44页

作者： M.Fukumoto N.Maeda B.Wei D.Suzuki 高丽华(译) 日本爱知县不详

我们之前对热喷涂金属粒子的扁平化转变行为进行了系统研究,并提出了形成机制假设:由于超快速冷却而优先在熔滴底部形成的冷却晶体结构决定着圆饼状熔滴的形成。为了验证这一机制是否适用其他材料,选取了几种具有不同热性能的陶瓷材料... 详细信息

我们之前对热喷涂金属粒子的扁平化转变行为进行了系统研究,并提出了形成机制假设:由于超快速冷却而优先在熔滴底部形成的冷却晶体结构决定着圆饼状熔滴的形成。为了验证这一机制是否适用其他材料,选取了几种具有不同热性能的陶瓷材料来进行对比。采用等离子喷涂技术分别将Al_2O_3、Y_2O_3和YSZ喷涂到AISI304不锈钢基体上,对圆饼状熔滴百分比随基体温度变化规律进行了研究,并对熔滴的横截面形貌也进行了观察。结果表明,在Al_2O_3和Y_2O_3熔滴底部均存在独特的非晶和冷晶结构,说明这些材料中圆饼状熔滴形成机制与金属中的相似。另一方面,在YSZ熔滴中却只有柱状晶结构,故圆饼状颗粒的形成机制假设只是适用于部分材料。

关键词：等离子喷涂陶瓷材料扁平化

Evaluation of the performance of yielding rockbolts during rockbursts using numerical modeling method

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International Journal of Coal Science & Technology 2022年第6期9卷 25-50页

作者： Jun Wang Derek b.Apel Huawei Xu Chong wei School of Mining and Petroleum Engineering University of AlbertaT6G 2R3 EdmontonABCanada

Rockburst;Rockburst damage;Yielding rockbolt;Numerical modeling;UDEC;Underground miningThe assessment of yielding rockbolt performance during rockbursts with actual seismic loading is essential for rock-burst supporting designs.In this paper,two types of yielding rockbolts(D-bolt and Roofex)and the fully resin-grouted rebar bolt are modeled via the"rockbolt"element in universal distinct element code(UDEC)after an exact calibration procedure.A two-dimensional(2D)model of a deep tunnel is built to fully evaluate the performance(e.g.,capacity of energy-absorption and control of rock damage)of yielding and traditional rockbolts based on the simulated rockbursts.The influence of different rockburst magnitudes is also studied.The results suggest that the D-bolt can effectively control and mitigate rockburst damage during a weak rockburst because of its high strength and deformation capacity.The Roofex is too"soft"or"smooth"to limit the movement of ejected rocks and restrain the large deformation,although it has an excellent deformation capacity.The resin-grouted rebar bolt can maintain a high axial force level during rockbursts but is easy to break during dynamic shocks,which fails to control rapid rock bulking or ejection.Three types of rockbolts cannot control the large deformation and mitigate rockburst damage effectively during violent rockbursts.The rockburst damage severity can be significantly reduced by additional support with cable bolts.This study highlights the effectiveness of numerical modeling methods in assessing the complex performance of yielding rockbolts during rockbursts,which can provide some references to improve and optimize the design of rock supporting in burst-prone grounds.

关键词： Rockburst Rockburst damage Yielding rockbolt Numerical modeling UDEC Underground mining

Shear behavior of ultrafine magnetite tailings subjected to freeze-thaw cycles

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International Journal of Mining Science and Technology 2019年第4期29卷 609-616页

作者： Chong wei Derek b.Apel Yunhai Zhang School of Mining and Petroleum Engineering University of AlbertaEdmontonAlberta T6G 2R3Canada School of Resources and Safety Engineering Central South UniversityChangsha 410083China

To study the shear behavior of the ultrafine magnetite tailings subjected to freeze-thaw cycles,unconsolidated-undrained shear tests were conducted on ultrafine-grained tailings that were subjected to 1-11 cycles of freeze-thaw and defined as a type of clayey silt under confining pressures of 100,200,and 300 kPa.Taking the number of freeze-thaw cycles,cooling temperature,initial dry density,and moisture content as the four main influencing factors of shear behavior of the tailings samples,the shear stress-strain curve,compression modulus,failure strength,cohesion,and internal friction angle were measured.The results show that the freeze-thaw cycle has an obvious weakening effect on the shear behavior of the tailings material,and the shear mechanical parameters are affected by a combination of confining pressure,freeze-thaw cycle condition,and initial physical-mechanical properties of the tailings samples.Through the microstructural analysis of the tailings samples subjected to freeze-thaw cycles,it shows that the freeze-thaw cycle mainly affects the porosity,bound water,and arrangement of the tailings particles.Subsequently,the macroscopic changes in shear strength indexes emerge,and then the stability of the tailings dam will decrease.

关键词： Ultrafine magnetite tailings(UMT) Freeze-thaw cycle Shear behavior Triaxial shear test

Undersea buried Pipeline Reconstruction based on the Level Set and Inverse Multiquadric Regularization Method

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Journal of Ocean University of China 2022年第1期21卷 101-112页

作者： SHANG Wenjing XUE wei XU Yidong MAKAROV Sergey b LI Yingsong College of Information and Communication Engineering Harbin Engineering UniversityHarbin 150001China Key Laboratory of Advanced Marine Communication and Information Technology Ministry of Industry and Information TechnologyHarbin 150001China Yantai Research Institute and Graduate School of Harbin Engineering University Yantai 264006China Institute of Physics Nanotechnology and TelecommunicationsHigher School of Applied Physics and Space TechnologiesPeter the Great St.Petersburg Polytechnic UniversitySt.Petersburg 195251Russia

The electric inversion technique reconstructs the subsurface medium distribution from acquired data.On the basis of electric inversion,objects buried under the earth or seabed,such as pipelines and unexploded ordnance,are detected and located in a contactless manner.However,the process of accurately reconstructing the shape of the target object is challenging because electric inversion is a nonlinear and ill-posed problem.In this work,we present an inverse multiquadric(IMQ)regularization method based on the level set function for reconstructing buried pipelines.In the case of locating underwater objects,the unknown inversion area is split into two parts,the background and the pipeline with known conductivity.The geometry of the pipeline is represented based on the level set function for achieving a noiseless inversion image.To obtain a binary image,the IMQ is used as the regularization term,which‘pushes’the level set function away from 0.We also provide an appropriate method to select the bandwidth and regularization parameters for the IMQ regularization term,resulting in reconstructed images with sharp edges.The simulation results and analysis show that the proposed method performs better than classical inversion methods.

关键词： inverse problems level set function inverse multiquadric regularization method buried pipeline