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Journal of Materials Science & Technology 2024年第5期172卷 1-14页

作者： Yaofeng Luo Yan Wang Li Wang Bin Liu Yong Liu State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Dynamic recrystallization(DRX)is of great significance for the thermomechanical processing and microstructural regulation of TiAl intermetallics.However,the underlying DRX mechanism remains poorly understood.In this study,an Avrami kinetics model for DRX was established,which was capable of predicting the DRX fraction accurately.In addition,the effect of Al_(2)O_(3)short fiber on the DRX mechanisms of TiAl matrix composite during the isothermal compression was investigated for the first time.The re-sults showed that other than inhibiting DRX by particles in the TiAl matrix composites,the addition of Al_(2)O_(3)short fiber accelerated a novel DRX process,which was induced by twinning and twin intersec-tions(TDRX).Thus,this composite exhibited a higher DRX rate than that of the as-cast TiAl monolithic alloy.The origin of the twin intersection and TDRX for the composite was revealed.The stress concentration near the Al_(2)O_(3)fiber was above the critical shear stress for twinning and thus was favorable for the formation of twinning and twin intersections.The high stored strain energy at the regions of twins and twin intersections provided the driving force for TDRX.TDRX accelerated the grain refinement in the TiAl matrix near the Al_(2)O_(3)fiber.The present findings would provide a new perspective on DRX mechanisms,and provide the scientific guidance for optimizing the microstructures of TiAl matrix composites.

关键词： TiAl matrix composite Al_(2)O_(3)fiber Twin intersection Dynamic recrystallization

Porous TiFe_(2) intermetallic compound fabricated via elemental powder reactive synthesis

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International Journal of Minerals,metallurgy and Materials 2024年第4期31卷 764-772页

作者： Qian Zhao Zhenli He Yuehui He Yue Qiu Zhonghe Wang Yao Jiang State Key Laboratory of Powder Metallurgy Powder Metallurgy Research InstituteCentral South UniversityChangsha 410083China

Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis.Herein,porous Ti Fe2intermetallics were fabricated by the reactive synthesis of elemental powders.The phase transformation and pore formation of porous TiFe2intermetallics were investigated,and its corrosion behavior and hydrogen evolution reaction(HER)performance in alkali solution were studied.Porous TiFe2intermetallics with porosity in the range of 34.4%-56.4%were synthesized by the diffusion reaction of Ti and Fe elements,and the pore formation of porous TiFe2intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect.The porous TiFe2samples exhibit better corrosion resistance compared with porous 316L stainless steel,which is related to the formation of uniform nanosheets on the surface that hinder further corrosion,and porous TiFe2electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA·cm-2,suggesting a good catalytic performance.The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance,showing its potential in the field of filtration and separation.

关键词： TiFe2 intermetallic compound porous materials reactive synthesis corrosion behavior hydrogen evolution reaction

Weatherability and heat resistance enhanced by interaction between AG25 and Mg/AI-LDH

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Rare Metals 2024年第6期43卷 2758-2768页

作者： Pei-Yao Yang Xiang-Cui Liu Yu-Chao Wang Huan-Ran Zheng Jin-Xian Wang Jia-Yi Zheng Meng-Jie Liu Dan-Ni Deng Yu Bai Ying-Bi Chen Tong Zhang Zhi-Ming Liu Yong-Peng Lei 1.State Key Laboratory of Powder Metallurgy,powder metallurgy Research Institute,Central South University 2.Research Institute of Chemical Defense State Key Laboratory of Powder Metallurgy Powder Metallurgy Research InstituteCentral South University Research Institute of Chemical Defense

Although inorganic pigments in common spectral tuning materials show good weatherability and heat resistance,the limited color choices,weak coloring power,poor dispersibility,and a possibility of toxicity limit their development.On the basis of organic pigments which possess a wide range of colors,high coloring power,good transparency,and high safety,herein,the modified pigment and biomimetic coating with improved weatherability,especially ultraviolet(UV) resistance(from 2 to 6 days),was achieved by intercalating acid green 25(AG25) pigment into Mg/Al-layered double hydroxides(Mg/Al-LDH).Furthermore,the heat resistance of AG25 was also significantly increased.Moreover,the spectral stability of pigments after heat treatment is superior with almost unchanged spectral profile and green reflection peak.The formation of strong N-H bonds and the S-M(Mg,Al)bonds between Mg/Al-LDH laminates and AG25 molecules contributes to the improvement.This work shows potential for biomimetic leaf materials in respect of reflective spectra stability.

关键词： Layered double hydroxide Biomimetic Acid green 25 Interaction Weatherability Heat resistance

Crosslinked solubilizer enables nitrate-enriched carbonate polymer electrolytes for stable,high-voltage lithium metal batteries

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Science Bulletin 2024年第2期69卷 209-217页

作者： Chuyang Jing Kuan Dai Dong Liu Wenran Wang Libao Chen Chunxiao Zhang Weifeng Wei State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China College of Materials and Chemical Engineering Hunan Institute of EngineeringXiangtan 411104China

High-voltage lithium metal batteries(LMBs)have been considered promising next-generation highenergy-density batteries.However,commercial carbonate electrolytes can scarcely be employed in LMBs owing to their poor compatibility with metallic lithium.N,N-dimethylacrylamide(DMAA)-a crosslinkable solubilizer with a high Gutmann donor number-is employed to facilitate the dissolution of insoluble lithium nitrate(LiNO3)in carbonate-based electrolytes and to form gel polymer electrolytes(GPEs)through in situ polymerization.The Lit solvation structure of the GPEs is regulated using LiNO3 and DMAA,which suppresses the decomposition of LiPFe and facilitates the formation of an inorganic-rich solid electrolyte interface.Consequently,the Coulombic efficiency(CE)of the LillCu cell assembled with a GPE increases to 98.5%at room temperature,and the high-voltage LillNCM622 cell achieves a capacity retention of 80.1%with a high CE of 99.5%after 400 cycles.The bifunctional polymer electrolytes are anticipated to pave the way for next-generation high-voltage LMBs.

关键词： Crosslinked solubilizer Lithium nitrate Carbonate electrolytes Gel polymer electrolytes Lithium metal batteries

Understanding the dehydrogenation properties of Mg(0001)/MgH_(2)(110)interface from first principles

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Materials Reports(Energy) 2024年第1期4卷 89-94页

作者： Jianchuan Wang Bo Han Zhiquan Zeng Shiyi Wen Fen Xu Yong Du State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083PR China powder metallurgy Research Institute Central South UniversityChangsha410083PR China Guangxi key laboratory of Information Materials Guilin University of Electronic TechnologyGuilin541004PR China

Magnesium hydride is one of the most promising solid-state hydrogen storage materials for on-board application.Hydrogen desorption from MgH_(2) is accompanied by the formation of the Mg/MgH_(2) interfaces,which may play a key role in the further dehydrogenation process.In this work,first-principles calculations have been used to understand the dehydrogenation properties of the Mg(0001)/MgH_(2)(110) interface.It is found that the Mg(0001)/MgH_(2)(110) interface can weaken the Mg-H bond.The removal energies for hydrogen atoms in the interface zone are significantly lower compared to those of bulk MgH_(2).In terms of H mobility,hydrogen diffusion within the interface as well as into the Mg matrix is considered.The calculated energy barriers reveal that the migration of hydrogen atoms in the interface zone is easier than that in the bulk MgH_(2).Based on the hydrogen removal energies and diffusion barriers,we conclude that the formation of the Mg(0001)/MgH_(2)(110) interface facilitates the dehydrogenation process of magnesium hydride.

关键词： Magnesium hydrides First-principles calculation Hydrogen storage materials Interface Hydrogen desorption

Preheating-assisted solid-state friction stir repair of Al-Mg-Si alloy plate at different rotational speeds

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International Journal of Minerals,metallurgy and Materials 2024年第4期31卷 725-736页

作者： Hui Wang Yidi Li Ming Zhang Wei Gong Ruilin Lai Yunping Li State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Research Institute of Light Alloy Central South UniversityChangsha 410083China

Additive friction stir deposition(AFSD)is a novel structural repair and manufacturing technology has become a research hotspot at home and abroad in the past five years.In this work,the microstructural evolution and mechanical performance of the Al-Mg-Si alloy plate repaired by the preheating-assisted AFSD process were investigated.To evaluate the tool rotation speed and substrate preheating for repair quality,the AFSD technique was used to additively repair 5 mm depth blind holes on 6061 aluminum alloy substrates.The results showed that preheat-assisted AFSD repair significantly improved joint bonding and joint strength compared to the control non-preheat substrate condition.Moreover,increasing rotation speed was also beneficial to improve the metallurgical bonding of the interface and avoid volume defects.Under preheating conditions,the UTS and elongation were positively correlated with rotation speed.Under the process parameters of preheated substrate and tool rotation speed of 1000 r/min,defect-free specimens could be obtained accompanied by tensile fracture occurring in the substrate rather than the repaired zone.The UTS and elongation reached the maximum values of 164.2MPa and 13.4%,which are equivalent to 99.4%and 140%of the heated substrate,respectively.

关键词： additive friction stir deposition structural repair tool rotation speed Al alloy

Developing Core-Shell Nano-Structures in FeCrAl-ODS Ferritic Alloys with the Co-Addition of Ni and Zr

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 364-372页

作者： Wenquan Ding Jieli Ma Yong Jiang Yiren Wang Huiqun Liu key laboratory for Nonferrous Materials of Ministry of Education School of Materials Science and EngineeringCentral South UniversityChangsha410083China National key laboratory for powder metallurgy Central South UniversityChangsha410083China

A new Ni+Zr co-alloyed FeCrAl-ODS(oxide-dispersion-strengthened)ferritic alloy was fabricated by ball-milling and hot-isostatic-pressing.Using electron microscopy and atom probe tomography,the dispersive formation of high density core-shelled nano-particles of various sizes was confirmed with a common B2-NiAl shell.Among which,median-sized nano-particles(20-50 nm)typically have an Y_(4)Al_(2)O_(9)nano-core of<~20 nm,ultra-fine nano-particles(<~20)nm have an Y_(4)Zr_(3)O_(12)nano-core of<~10 nm,and larger-sized nano-particles(50-100 nm)incorporate an ultra-fine Y_(4)Al_(2)O_(9)nano-core and a few ultra-fine Y_(4)Zr_(3)O_(12)nano-oxides.All these nano-phases were highly coherent with the ferritic matrix.No large Y--Al-O nano-oxides were formed.The total number density of ultra-fine nano-particles was estimated as~2×10^(23)m^(-3)with a mean size of 6.3 nm only,and accordingly,the new alloy achieved an excellent combination of strength and ductility at high temperatures.

关键词： FeCrAl Oxide-dispersion-strengthened(ODS)alloy Mechanical alloying Nano-oxides Core-shell

Nb-and Ta-doped(Hf,Zr,Ti)C multicomponent carbides with enhanced oxidation resistance at 2500℃

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Journal of Advanced Ceramics 2024年第3期13卷 332-344页

作者： Shiyan Chen Jinming Wang Zhaoke Chen Weilong Song Yi Zeng Xingchao Li Tongqi Li Xiang Xiong State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Aerospace Research Institute of Materials&Processing Technology China Academy of Launch Vehicle TechnologyBeijing 100076China

Enhancing oxidation resistance of multicomponent carbides above 2000℃is critical for their thermal protection applications.For this purpose,novel Nb-and Ta-doped(Hf,Zr,Ti)C multicomponent carbides were designed to improve their oxidation resistance at 2500℃.The results demonstrated that Nb and Ta doping reduced the oxidation rate constant by 16.67%and 25.17%,respectively,thereby significantly improving the oxidation resistance of(Hf,Zr,Ti)C.This enhancement was attributed to the changes in oxycarbide composition and distribution within the oxide layer by adding Nb and Ta.Owing to the different oxidation tendencies of the constituent elements,a distinctive structure was formed in which(Hf,Zr)O_(2)served as a skeleton,and various oxycarbides were dispersed throughout the oxide layer.The doped Nb and Ta were retained within oxycarbides,retarding the diffusion of oxygen into the lattice.More importantly,the addition of Nb and Ta reduced the size of oxycarbides,decreasing both size and quantity of the pores in the oxide layer and facilitating the formation of a more effective oxygen barrier.

关键词： (Hf,Zr,Ti)C oxidation behaviour ultra-high-temperature oxidation Nb and Ta doping oxycarbides

New steelmaking process based on clean deoxidation technology

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International Journal of Minerals,metallurgy and Materials 2024年第6期31卷 1249-1262页

作者： Zhongliang Wang Yanping Bao state key laboratory of Advanced metallurgy University of Science and Technology BeijingBeijing 100083China

After the converter steelmaking process,a considerable number of ferroalloys are needed to remove dissolved oxygen from the molten steel,but it also forms a lot of oxide inclusions that cannot be completely removed.At the same time,it increases the carbon emis-sions in the steel production process.After years of research,our team have developed a series of clean deoxidation technologies,includ-ing carbon deoxidation,hydrogen deoxidation,and waste plastic deoxidation of molten steel to address the aforementioned issues.In this study,thermodynamic calculations and laboratory experiments were employed to verify that carbon and hydrogen can reduce the total oxygen content in the molten steel melt to below 5×10^(-6) and 10×10^(-6),respectively.An analysis of the deoxidation mechanisms and ef-fects of polyethylene and polypropylene was also conducted.In addition,the applications of carbon deoxidation technology in different steels with the hot-state experiment and industrial production were discussed carefully.The carbon deoxidation experimental results of different steels were as follows:(1)the oxygen content of bearing steel was effectively controlled at 6.3×10^(-6) and the inclusion number density was lowered by 74.73%compared to aluminum deoxidized bearing steel;(2)the oxygen content in gear steel was reduced to 7.7×10^(-6) and a 54.49%reduction of inclusion number density was achieved with almost no inclusions larger than 5μm from the average level of industry gear steels;(3)a total oxygen content of M2 high-speed steel was as low as 3.7×10^(-6).In industrial production practice,car-bon deoxidation technique was applied in the final deoxidation stage for non-aluminum deoxidized bearing steel,and it yielded excellent results that the oxygen content was reduced to below 8×10^(-6) and the oxide inclusions in the steel mainly consist of silicates,along with small amounts of spinel and calcium aluminate.

关键词： clean deoxidation carbon deoxidation hydrogen deoxidation waste plastics deoxidation

Development and prospects of molten steel deoxidation in steelmaking process

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International Journal of Minerals,metallurgy and Materials 2024年第1期31卷 18-32页

作者： Zhongliang Wang Yanping Bao state key laboratory of Advanced metallurgy University of Science and Technology BeijingBeijing 100083China

In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets.

关键词： steel deoxidation deoxidizer metallurgical equipment bearing steel IF steel