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Plasticity-induced stacking fault behaviors ofγ'precipitates in novel CoNi-based superalloys

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Journal of Materials Science & Technology 2021年第31期90卷 20-29页

作者： w.-w.Xu G.H.Yin Z.Y.Xiong q.Yu T.q.Gang L.J.Chen School of Aerospace Engineering Xiamen UniversityXiamen 361005China

Implementation of novelγ/γ'Co-based superalloys with higher strength and improved creep durability is a challenging task for *** lack of atomic-level understanding of plastic deformation behavior has seriously limited the exploration of the full capacity of Co-based *** put forward a comprehensive study of generalized stacking fault energies by first principles to explore the effect of Ni and Al/w on the plastic deformation mechanism ofγ'precipitates in Co-based *** is found that alloying Ni and adjusting Al/w obviously change the dislocation glide and twinning nucleation in theγ'precipitates by altering the stable fault energies and the unstable fault energy *** addition of either Ni or w deteriorates the strength even the stability of *** ratio of effective planar fault energy(ΔEp)bridges intrinsic energy barriers and various deformation mechanisms of superalloys at elevated *** for alloying effects,the grain orientation also significantly governs the operation of the plastic deformation of *** theoretical results agree with the available measurements and well capture the observed phenomena in experiments.

关键词： Co-based superalloys Stacking fault energy Creep resistance First-principles method

Distribution of Be in a Ti-Based Bulk Metallic Glass Composite Containing B-Ti

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Journal of Materials Science & Technology 2017年第7期33卷 708-711页

作者： L.Zhang w.q.Li Z.w.Zhu H.M.Fu H.Li Z.K.Li H.w.Zhang A.M.wang H.F.Zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences 110016 Shenyang China

In order to obtain a glassy matrix during quenching, Be is often selected as a constituent of the compositions of Ti/Zr-based bulk metallic glass composites（BMGCs）. The in situ formed β phase in Be-bearing BMGCs was reported to be Be-free. However, a thorough investigation of the distribution of Be in BMGCs is still missing to date. In this work, the distribution of Be in a Ti_（47.5）Zr_（33）Cu_（5.8）Co_3Be_（12.5）（at.%） BMGC was studied by the secondary ion mass spectrometry（SIMS） and the electron energy loss spectroscopy（EELS）.It is found that Be almost totally dissolves in the glassy matrix, but a very weak intensity of Be in β phase is still detectable by SIMS, and the content of Be in β-Ti is estimated to be about 0.3 at.%. Based on the recently established two-phase quasi-equilibrium of BMGCs, the distinct solubility of Be in the glassy matrix and in β-Ti has been explained.

关键词： Bulk metallic glass(BMG) Metallic glass composite Beryllium quasi-equilibrium

The Novel Mechanical Property of Tongue of a woodpecker

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Journal of Bionic Engineering 2009年第3期6卷 214-218页

作者： P Zhou X q Kong C w wu Z Chen National Key Laboratory for Structural Analysis of Industrial Equipment Dalian University of Technology Department of Civil and Environmental Engineering University of Missouri

Biomaterials such as bone,teeth,nacre and silk are known to have superior mechanical properties due to their specific nanocomposite *** we report that the woodpecker's tongue exhibits a novel strength and flexibility due to its special composite micro/*** tongue consists of a flexible cartilage-and-bone skeleton covered with a thin layer tissue of high strength and *** the interface between the cartilage-and-bone skeleton and the tissue layer,there is a hierarchical fiber-typed *** is this special design of the tongue that makes the woodpeckers efficient in catching the insects inside *** special micro/nanostructures of the woodpecker's tongue show us a potential method to enhance the interfacial connection between soft and hard material layers for bio-inspired composite system designs.

关键词： woodpeckcr hyoid cartllage multilevel structure tensile strength

Synthesis and Properties of Layered Oxides LiCo_(1-x)Ni_xO_2

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Journal of Materials Science & Technology 1997年第5期13卷 405-408页

作者： Lin, q Chen, N Ye, w Liu, RM Luo, JS GEN RES INST NONFERROUS MET BEIJING 100088PEOPLES R CHINA

The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from carbonates can be divided into two steps. Below 300℃cobalt carbonate and/or nickel carbonate decompose forming oxides. Over 300℃ Li2CO3 decomposes and reacts with Co and/or Ni oxides gradually, as a result Co++ and/or Ni++ areoxidized to Co+++ and/or Ni+++, finally LiCo1-xNixO2 forms. The proportion of cobalt tonickel in the starting mixture and atmosphere during synthesis affects the structure of ***1-xNixO2(x≤0.5) can be synthesized in air or oxygen and characterized by solid solutionof LiCoO2 and LiNiO2. LiNiO2 can be obtained only from hydrates and in oxygen *** and LiCo0.5Ni0.5O2 have higher first charge capacity than that of LiCoO2. Their discharge capacity reaches a level with that of LiCoO2 and has reasonable reversibility.

关键词： Lithium batteries

Influence of Fe Addition on Products of Self-Propagating High-Temperature Synthesis Reaction in 3Ti-Si-2C System

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稀有金属材料与工程 2009年第A3期38卷 113-118页

作者： Guan q L wang H Y Li S L Si w P Jiang q C Key Laboratory of Automobile Materials of Ministry of Education Jilin University Changchun 130025 China

Influence of Fe addition on products of self-propagating high-temperature synthesis (SHS) reaction in 3Ti-Si-2C system was investigated in the present study. without Fe addition, Ti5Si3 and TiC are the dominant phases along with a small amount of Ti3SiC2 phase and unreacted C left in the final products. As Fe content ranges from 10% to 30%, the products consist of TiC, Ti5Si3, Fe2Ti and unreacted C, but no trace of Ti3SiC2 phase is detected. Furthermore, the amounts of both Fe2Ti and C phases increase with Fe content increasing. Addition of Fe has a great effect on the reaction route and significantly restrains the formation of Ti3SiC2 during the combustion synthesis process, and therefore, the SHS is not an effective fabrication technique to synthesize the ternary Ti3SiC2 ceramic in either 3Ti-Si-2C or Fe-3Ti-Si-2C system. Besides, without Fe addition, Ti5Si3 presents as the coarse irregular appearance with an obviously sintered morphology. In contrast, the shape of Ti5Si3 exhibits more and more spherical (cobblestone-like) and the surface becomes increasingly smooth, because the amount of liquids formed during the SHS reaction increases with the increase of Fe content. On the other hand, with Fe content increasing from 0 to 30 wt.%, the particulate size of TiC decreases from more than 5 μm to 1 μm or less, mainly due to the fact that the combustion temperature decreases with the increase of Fe content in the preforms.

关键词：复合材料铁含量燃烧过程物理性能

Effective yield strength of a saturated porous medium with a spheroidal meso-pore and spherical micro-pores

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Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第1期3卷 97-104页

作者： w.q.Shen College of Architecture and Energy Engineering Wenzhou University of TechnologyWenzhou325000China Department of Civil Engineering Polytech LilleUniversity of LilleFrance

A macroscopic yield criterion has been derived in the present work for a double saturated porous medium with a spheroidal pore at the mesocale and spherical pores at the *** two types of pores are well separated at two different *** meso spheroidal pore saturated by a pore pressure which is different from the one in the micro spherical pores.A Drucker-Prager type criterion is adopted for the solid phase at the microscopic scale to describe its asymmetric behavior between tension and *** methodology to formulate this criterion is based on the limit analysis approach of a spheroidal volume containing a confocal spheroidal pore subjected to a uniform strain rate boundary *** matrix at the mesoscopic scale obeys to a general elliptic yield *** on a two-step homogenization step,the influence of meso-pore shape(spherical,prolate or oblate),micro-porosity,meso-porosity and the effect of pore pressures at different scales are taken into account explicitly by this macroscopic yield criterion.

关键词： Double porous materials Saturated Spheroidal pore Macroscopic yield criterion Plasticity Gurson-type model

A Model of Tangential Contact Damping Considering Asperity Interaction and Lateral Contact

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Acta Mechanica Solida Sinica 2018年第6期31卷 758-774页

作者： w.P.Fu Z.q.Gao w.wang J.B.wu School of Mechanical and Precision Instrument Engineering Xi'an University of TechnologyXi'an 710048 China

A precise tangential contact damping model is proposed,which includes the lateral contact of the upper-lower asperities and the interaction of adjacent *** effects of the normal static preload,frequency,and amplitude of tangential displacement on the tangential contact damping were analyzed by simulation,***,the results of simulation are verified by *** tangential contact damping of considering the interaction and lateral contact of asperity is very close to the experimental results.

关键词： Asperity Lateral contact Interaction Tangential contact damping

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等离子喷涂纳米陶瓷热障涂层组织与性能

航空制造技术 2004年第Z1期47卷 220-224页

作者： w.q. wang D.q. Sun w.B. Gong Z.Z. Xuan

采用纳米陶瓷粒子团聚体粉末等离子喷涂制备纳米陶瓷热障涂层,研究了纳米陶瓷热障涂层的组织和性能.试验表明,采用纳米结构的陶瓷涂层有利于增加热障涂层的高温使用寿命.

关键词：热障涂层等离子喷涂纳米陶瓷涂层组织性能

A new model for the expansion tube considering the stress coupling:Theory,experiments and simulations

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Defence Technology（防务技术） 2022年第7期18卷 1190-1204页

作者： M.Z.wu X.w.Zhang q.M.Zhang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyHaidian DistrictBeijing10081China

Based on the two-arc profile assumption,the expansion deformation and energy absorption of circular tubes compressed by conical-cylindrical dies were ***,the deformation of the two arcs was analyzed independently and an improved model denoted as Model-I was ***,by further involving the coupling between the bending moment and membrane forces,a more elaborate model,i.e.,Model-II was ***,experiments and simulations were conducted to verify the models,which show that,compared with previous theoretical models,Model-II could not only capture the prominent features of the deformation,but also improve the prediction accuracy of the steady driving force *** means of this model,it was found that the critical semi-conical angle,which makes the driving force minimum,increases with the increase of the friction coefficient,expansion ratio as well as the radius/thickness ratio of the ***,the energy dissipation due to stretching is always greater than that of bending,while the friction dissipation can account for the largest proportion at small semi-conical angle or large friction *** a certain friction and die conditions,the specific energy absorption of expanded tubes can be much higher than that under progressive collapse mode.

关键词： Expansion Circular tube Stress coupling Strain hardening Energy absorption