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In-situ composite microstructure formation of immiscible alloy solidified in space

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National Science Review 2023年第2期10卷 88-90页

作者： Jiuzhou Zhao Hao Sun Lili Zhang Hongxiang Jiang Linjie Yang Jie He Shi-Changxu Innovation Center for Advanced Materials Institute of Metal Research Chinese Academy of Sciences School of materials Science and Engineering University of Science and Technology of China

About one-third of alloys show a phase diagram with a miscibility gap in the liquid state.The solidifications of these alloys proceed with a liquid-liquid decomposition and have great potential in the development of high-performance in-situ particulate composites,and composites with a core/shell structure.However,these alloys generally show a phase segregated microstructure when solidified on the ground.Since the 1960s,

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The thin-wall debit of a typical cast polycrystalline M951 alloy

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Progress in Natural Science:materials International 2022年第1期32卷 104-113页

作者： Qi Li Jun Xie Jin Jiang Yu Delong Shu Guichen Hou Xiaofeng Sun Yizhou Zhou Shi-Changxu Innovation Center for Advanced Materials Institute of Metal Research Chinese Academy of Sciences School of materials Science and Engineering University of Science and Technology of China

The effect of specimen thickness on the rupture properties of cast Ni-based polycrystal superalloy M951 was investigated in this paper. The results of the rupture tests in air under 980°C/90 MPa revealed that the rupture life and elongation obviously decreased with decreasing specimen thickness. The thin-wall effect for polycrystal superalloy M951 is associated with several factors. First, the surface oxidation and internal nitridation induce the reduction in the load-bearing section, which accelerates the rupture fracture of thin specimens. Second, the combined effect of oxidation and stress at the surface grain boundary facilitates the premature initiation and propagation of the surface cracks in thin specimen. Third, the through-grain boundaries introduce by specimens machining are detrimental for rupture property. A direct comparison of rupture properties of thin-wall samples with different grain morphologies indicate that thin-wall effect can be diminished by avoiding through-grain boundary introduction.

关键词： M951 Thin-wall debit Surface crack Through-grain boundary

High-Temperature Oxidation Behavior and Related Mechanism of RuT400 Vermicular Graphite Iron

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Acta Metallurgica Sinica(English Letters) 2022年第7期35卷 1117-1130页

作者： Yu Chen Jian-chao Pang Shou-xin Li Zhe-feng Zhang Henan Institute of advanced Technology Zhengzhou UniversityZhengzhou 450001China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The vermicular graphite iron is an important material with excellent combination properties for cylinder heads of diesel engines,and the high-temperature oxidation is a crucial problem during service of the component.In this study,the oxidation experiment of RuT400 vermicular graphite iron was performed at 500 ℃,and the oxidation time was chosen as 100 h,200 h,300 h,400 h,and 500 h,respectively.Meanwhile,the corresponding microstructure evolution,oxidation kinetics,and oxidation mechanism were discussed.It is found that oxidation pores and oxide layer often appear at the vermicular graphite on the specimen surface;the vermicular graphite plays the role of oxidation channel,and it tends to diff use along the adjacent pearlite and then connect with each other to form oxidation bridges as the oxidation time prolongs.A linear relationship between oxidation weight gain and the thickness of the oxide layer was established and verifi ed well.These results will give a more comprehensive understanding on the oxidation mechanism of vermicular graphite iron and provide certain guidance for design and preparation of anti-oxidation cast irons.

关键词： Vermicular graphite iron High-temperature oxidation Microstructure evolution Oxidation mechanism

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Martensite decomposition under thermal-mechanical coupling conditions to fabricate an ultrafine-grained Ti6Al4Mo4Zr1W0.2Si alloy

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Journal of materials Science & Technology 2024年第1期168卷 157-168页

作者： Taoyu Zhou Jiuxu Yang Nan Li Hao Sun Bohua Zhang Zibo Zhao Qingjiang Wang Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The fabrication of ultrafine-grained microstructures(grain size below 1μm)in titanium alloys is beneficial for improving their mechanical properties at room temperature and medium tempera-tures(400-550°C).However,a long-standing challenge involves the low-cost manufacturing of bulk ultrafine-grained titanium alloys.In this work,we developed a facile strategy through martensite de-composition at thermal-mechanical coupling conditions,to fabricate an equiaxed microstructure in a Ti6Al4Mo4Zr1W0.2Si model alloy with an averageαgrain size of 315±62 nm.The formation of the ultrafine-grained microstructure was because the lattice strain stored in the martensitic initial mi-crostructure enhanced the nucleation rate of dynamic recrystallization,meanwhile,the pinning role of martensite decomposition productsβand(Ti,Zr)_(5)Si_(3)phases suppressed grain coarsening at high tem-peratures.Compared to conventional(α+β)alloys,the tensile strength of this alloy improved by 20%-30%at both room temperature and 550°C,without decreasing its ductility.In situ SEM observations revealed that the ultrafine-grained microstructure would not only suppress dislocation motions but also contribute to the homogenous deformation in the matrix of the material,therefore,it resulted in higher mechanical performance.The research results may be of great significance to the development of next-generation aviation titanium alloys.

关键词： Ultrafine-grained Titanium alloy In situ observation Deformation mechanism Thermostability

Atomic scale investigation of FCC→HCP reverse phase transformation in face-centered cubic zirconium

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Journal of materials Science & Technology 2023年第6期137卷 8-13页

作者： Wenbin Guo Fuzhou Han Geping Li Yingdong Zhang Muhammad Ali Jie Ren Qichen Wang Fusen Yuan School of materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Mechanism of FCC→HCP reverse phase transformation in face-centered cubic zirconium(FCC-Zr)along with a concomitant 70.5°rotation ofα-Zr matrix were investigated in zircaloy-4(Zr-4)cladding tube by using transmission electron microscopy(TEM).Results showed that the interaction among a secondary phase particle(SPP)and three FCC-Zr grains resulted in the formation of cross stacking faults in SPP and exerted a drag force on minor axis of the adjacent FCC-Zr phase.Moreover,when the shear stress along[112]_(FCC-Zr)direction was large enough to initiate the emission of 1/6[112]Shockley partial dislocation on every other(111)_(FCC-Zr)close-packed plane,the stacking sequence would change from ABC ABCA to AB ABABA viz.(0001)planes of the daughter HCP phase.Thus,FCC→HCP reverse phase transformation in FCC-Zr was presented.

关键词： Zircaloy-4 Reverse phase transformation Fcc-Zr phase Interaction

Microstructure,Mechanical,and Tribological Properties of Amorphous WB2/Ti Multilayer Coatings

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金属学报:英文版 2023年第8期36卷 1385-1396页

作者： Wenhe Li Wenshuang Gu Yuqiu Chen Jun Gong Zhiliang Pei Chao Sun Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang110016China

Amorphous WB2/Ti multilayer coatings with different modulation ratios(1,5,15,and 30)and different bilayer numbers(10,20,30,50,and 70)were deposited by direct-current magnetron sputtering.The effect of modulation ratio and bilayer number on the microstructure,mechanical,and tribological properties of WB2/Ti multilayer coatings was studied systematically.In the investigation for the influence of modulation ratio,the hardness of the multilayer coatings increases with the increment of modulation ratio.The indentation toughness shows a different changing tendency compared to that of the hardness with different modulation ratios.The wear rates of the multilayer coatings with different modulation ratios are at the same level with the influence of both hardness and indentation toughness.In the investigation for the influence of bilayer number,both hardness and indentation toughness increase first and then decrease with an increasing bilayer number.WB2/Ti multilayer coating with a modulation ratio of 5 and bilayer number of 50 exhibits the highest hardness of 20.4 GPa and lowest wear rate of 1.76×10−16 m3/Nm.In addition,the hardness strengthening mechanism and wear mechanism of the multilayer coatings were discussed in detail.

关键词： Magnetron sputtering WB /Ti multilayer Mechanical properties Tribological properties

Cryogenic wear behaviors of a metastable Ti-based bulk metallic glass composite

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Journal of materials Science & Technology 2023年第3期134卷 33-41页

作者： Yue Ren Tingyi Yan Zhuobin Huang Qing Zhou Ke Hua Xiaolin Li Yin Du Qian Jia Long Zhang Haifeng Zhang Haifeng Wang State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Bulk metallic glass composites(BMGCs)are proven to be excellent candidates for cryogenic engineering applications due to their remarkable combination of strength,ductility and toughness.However,few efforts have been done to estimate their wear behaviors that are closely correlated to their practical service.Here,we report an improvement of∼48%in wear resistance for a Ti-based BMGC at the cryogenic temperature of 113 K as compared to the case at 233 K.A pronounced martensitic transformation(β-Ti→α''-Ti)was found to coordinate deformation underneath the worn surface at 233 K but was significantly suppressed at 113 K.This temperature-dependent structural evolution is clarified by artificially inducing a pre-notch by FIB cutting on aβ-Ti crystal,demonstrating a strain-dominated martensitic transformation in the BMGC.The improved wear resistance and suppressed martensitic transformation in BMGC at 113 K is associated with the increased strength and strong confinement of metallic glass on metastable crystalline phase at the cryogenic temperature.The current work clarifies the superior cryogenic wear resistance of metastable BMGCs,making them excellent candidates for safety-critical wear applications at cryogenic temperatures.

关键词： Bulk metallic glass composites Martensitic transformation Cryogenic temperature Wear

Morphology-controlled CoNi/C hybrids with bifunctions of efficient anti-corrosion and microwave absorption

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Journal of materials Science & Technology 2022年第7期102卷 24-35页

作者： Jianwen Ge Yu Cui Jiaxin Qian Li Liu Fandi Meng Fuhui Wang Shenyang National Laboratory for materials Science Northeastern UniversityShenyang 110819China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Till now,fewer literatures have investigated the corrosion resistance of microwave absorbers,especially mental@C/carbon matrix derived from MOF composites,although it is known that carbon shells possess a protective effect.Herein,three kinds of morphology-controlled CoNi/C-N doped architectures were suc-cessfully fabricated via a sequence of processing,namely coprecipitation for ZIF-67,subsequent Ni^(2+) ex-change and ultimate carbonization.Apart from composition characterization,the effects of microstructure tailoring and temperature controlling on electromagnetic response as well as attenuation performance were revealed,where dodecahedron-shaped composites possessed the highest permittivity.By contrast,rod-shaped composites(CoNi/C-r-550 and CoNi/C-r-700)were endowed with superior comprehensive ab-sorption properties,e.g.,RL_(min):-49.8 dB and-64.0 dB;EAB:5.7 GHz and 4.8 GHz,respectively.Besides,samples CoNi/C-d-700 and CoNi/C-r-700 present higher corrosion potential(E_(corr))and lower corrosion current(I corr).Hence,these corrosion-resistant microwave absorbers with outstanding absorption stabil-ity,wetting effect as well as environmental adaptability,can be used as a candidate/raw material for intelligent devices.

关键词： Electromagnetic response Morphological-anisotropic Anticorrosive ZIF-67

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Microwave absorption performance of porous carbon particles modified by nickel with different morphologies

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Journal of materials Science & Technology 2023年第6期137卷 79-90页

作者： Zhangtao Shen Yapei Zu Yuqiu Chen Jun Gong Chao Sun School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

In this work,porous carbon particles were prepared from wheat flour by pyrolysis and activation.Through the subsequent coprecipitation and electroless plating,the surface and pores of carbon particles were modified by nickel-rich particles with different morphologies.Several loss mechanisms,including dielectric loss,magnetic loss,multiple reflection and scattering loss,were used to assess the attenuation ability to incident electromagnetic waves of these composite particles.The result shows that the chain-shaped morphology of nickel can provide the highest dielectric loss.Under the filler loading of 20 wt.%,the minimum reflection loss(RL min)reached-38.42 dB at 13.2 GHz,and the_(max)imum effective absorption bandwidth(EAB_(max))was 5.2 GHz with a matching thickness of 2 mm.The excellent performance of the composite particles is attributed to the synergistic effect of outstanding impedance matching and supe-rior electromagnetic loss ability caused by the chain structure.The result shows that the morphology of modifiers in carbon-based composites is important to improve microwave absorption performance,and this work provides inspiration for the design of high-performance porous carbon-based composites.

关键词： Porous carbon particles Nickel morphology Chain-shaped Microwave absorption performance