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Effect of La_(2)O_(3) addition on the synthesis of tungsten nanopowder via combustion-based method

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Journal of Materials Science & Technology 2020年第23期58卷 24-33页

作者： Zheng Chen mingli qin Junjun Yang Lin Zhang Baorui Jia Xuanhui Qu Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China

In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nanopowders with different La_(2)O_(3) doping amount(0.5~5.0 wt%) were successfully prepared by SCS and followed hydrogen reduction. The results showed that with the increase of La_(2)O_(3) addition,the product synthesized by SCS changed from needle-like W_(18) O_(49) to irregularly granulated H0.53 WO3 and the complete reduction temperature also increased form 700°C to 850°C. The densification behavior of as-prepared W nanopowders revealed that the densification inhibitory effect of La_(2)O_(3) was enhanced as the La_2O_3 addition increased. Nevertheless, due to the optimal size and distribution of La_(2)O_(3) particles,the sample with 2.0 wt% La_(2)O_(3) addition has a smallest grain size of 0.47 μm and a highest microhardness value of 739.3 Hv0.2, which are the best compared with the literature.

关键词： Tungsten nanopowder La_(2)O_(3)doped Solution combustion synthesis Influence

Manufacturing of Injection-Molded NdFeB Magnet with (BH)max111 kJ · m-3

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Journal of Rare Earths 2004年第Z1期22卷 69-72页

作者： Duan Bohua Qu Xuanhui Xu Zhengzhou Guo Shibo qin mingli State Key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China State Key Laboratory for Powder MetallurgyCentral South UniversityChangsha 410083China Beijing Key Laboratory for Advanced Powder Metallurgy &Particulate Materials University of Science and Technology Beijing Beijing 100083 China Beijing Key Laboratory for Advanced Powder Metallurgy &Particulate Materials University of Science and Technology Beijing Beijing 100083 China Beijing Key Laboratory for Advanced Powder Metallurgy &Particulate Materials University of Science and Technology Beijing Beijing 100083 China Beijing Key Laboratory for Advanced Powder Metallurgy &Particulate Materials University of Science and Technology Beijing Beijing 100083 China

The bonded NdFeB magnets prepared by injection molding meet with the development tendency of the magnet in small volume, light weight and high performance ,and have a good *** this paper, a modified nylonbased binder was developed for powder injection molding of NdFeB bonded *** effects of pretreatment of NdFeB anisotropic magnetic powder produced with HDDR processing on the anti-oxidation behaviors of powder and the final magnetic properties of the molded bonded magnets were *** optimal powder loading of 65 vol% was achieved with the modified *** was found that the properties of the bonded magnets were mainly affected by the powder surface pretreatment and the intensity of the applied alignment magnetic field during injection molding for a certain *** magnets with remanence of 0.820 T, intrinsic coercivity of 1140.3 kA· m-1 and maximum energy product of 111 kJ · m-3 were produced with the optimal processing.

关键词： injection molding bonded NdFeB magnet surface treatment alignment magnetic field magnetic material rare earths

Phase equilibria in the Mg-rich corner of the Mg-Zn-La system at 350°C

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Rare Metals 2006年第5期25卷 572-575页

作者： LI Hongxiao REN Yuping HUANG mingli CHEN qin HAO Shiming School of Materials and Metallurgy Northeastern University Shenyang 110004 China

The phase equilibria in the Mg-rich comer of the Mg-Zn-La system at 350℃ have been investigated by scanning electron microscopy, X-ray diffraction, and electron probe microanalysis. It has been shown that the linear compound （Mg,Zn）17La2 existed in the Mg-Zn-La system at 350℃. The linear cornpound （so-called Tphase） was with the C-centred orthorhombic crystal structure induced by the solution of significant quantities of the third element. The three-phase region α（Mg）＋ MgZn（La）＋ T and the two-phase region composed of the α（Mg） and the linear-compound T phase existed in the Mg-rich comer of the Mg-Zn-La system at 350℃.

关键词： Mg-Zn-La system phase diagram linear compound

Influences of oxide content and sintering temperature on microstructures and mechanical properties of intragranular-oxide strengthened iron alloys prepared by spark plasma sintering

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International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1748-1755页

作者： Deyin Zhang Xu Hao Baorui Jia Haoyang Wu Lin Zhang mingli qin Xuanhui Qu Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Shunde Innovation School University of Science and Technology BeijingFoshan 528399China

How to increase strength without sacrificing ductility has been developed as a key goal in the manufacture of high-performance metals or alloys. Herein, the double-nanophase intragranular yttrium oxide dispersion strengthened iron alloy with high strength and appreciable ductility was fabricated by solution combustion route and subsequent spark plasma sintering, and the influences of yttrium oxide content and sintering temperature on microstructures and mechanical properties were investigated. The results show at the same sintering temperature,with the increase of yttrium oxide content, the relative density of the sintered alloy decreases and the strength increases. For Fe–2wt%Y_(2)O_(3)alloy, as the sintering temperature increases gradually, the compressive strength decreases, while the strain-to-failure increases. The Fe–2wt%Y_(2)O_(3)alloy with 15.5 nm Y_(2)O_(3)particles uniformly distributed into the 147.5 nm iron grain interior sintered at 650℃ presents a high ultimate compressive strength of 1.86 GPa and large strain-to-failure of 29%. The grain boundary strengthening and intragranular second-phase particle dispersion strengthening are the main dominant mechanisms to enhance the mechanical properties of the alloy.

关键词： oxide dispersion strengthening spark plasma sintering microstructure and properties strengthening mechanism

Pressureless two-step sintering of ultrafine-grained refractory metals:Tungsten-rhenium and molybdenum

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Journal of Materials Science & Technology 2022年第31期126卷 203-214页

作者： Zhongyou Que Zichen Wei Xingyu Li Lin Zhang Yanhao Dong mingli qin Junjun Yang Xuanhui Qu Ju Li Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China Department of Nuclear Science and Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA Department of Materials Science and Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA

The challenge of sintering ultrafine-grained refractory metals and alloys to full density is hereby addressed by pressureless two-step sintering in tungsten-rhenium alloy and pure molybdenum. Using properly processed nano powders(~50 nm average particle size), we are able to sinter W-10Re alloy to 98.4% density below 1200 ℃ while maintaining a fine grain size of 260 nm, and sinter molybdenum to 98.3% density below 1120 ℃ while maintaining a fine grain size of 290 nm. Compared to normal sintering,two-step sintering offers record-fine grain sizes and better microstructural uniformity, which translates to better mechanical properties with higher hardness(6.3 GPa for tungsten-rhenium and 4.0 GPa for molybdenum, both being the highest in all pressurelessly sintered samples of the respective material system)and larger Weibull modulus. Together with our previous demonstration in tungsten, we believe that twostep sintering is a general effective method to produce high-quality fine-grained refractory metals and alloys, and the lessons learned here are transferable to other materials for powder metallurgy.

关键词： Powder metallurgy Refractory metals Porosity Two-step sintering Grain growth

Oxygen variation in titanium powder and metal injection molding

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International Journal of Minerals,Metallurgy and Materials 2024年第12期31卷 2706-2713页

作者： Junping Shen Chang Liu Muhammad Dilawer Hayat Jianan Chen Hanqing Tian Fusheng Xin Gang Chen Fei Yang mingli qin Xuanhui Qu Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China School of Engineering The University of WaikatoHamilton 3216New Zealand Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation Beijing 100083China Ningbo Titan Advanced Materials Technology Co. Ltd.Ningbo 315012China

The control of oxygen is paramount in achieving high-performance titanium(Ti)parts by powder metallurgy such as metal in-jection molding(MIM).In this study,we purposely selected the Ti and Ti-6Al-4V powders as the reference materials since these two are the most representative Ti materials in the ***,hydride-dehydride(HDH)Ti powders were pre-oxidized to examine the ef-fect of oxygen variation on the characteristics of oxide layer on the particle surface and its resultant color *** results indicate that the thickness and Ti oxide level(Ti^(0)→Ti^(4+))of the oxide layer on the HDH Ti powders increased as the oxygen content increased,lead-ing to the transition of color appearance from grey,brown to *** work aids in the powder feedstock selection at the initial stage in powder *** addition,the development of oxygen content was comprehensively studied during the MIM process using the gas-atomized(GA)Ti-6Al-4V ***,the oxygen variation in the form of oxide layer,the change of oxygen content in the powders,and the relevant parts were investigated during the processes of kneading,injection,debinding,and *** oxygen vari-ation was mainly concentrated in the sintering stage,and the content increased with the increase of sintering *** variation of oxygen content during the MIM process demonstrates the crucial role of powder feedstock and sintering stage in controlling oxygen *** work provides a piece of valuable information on oxygen detecting,control,and manipulation for the powder and processing in the industry of Ti and its alloys by powder metallurgy.

关键词： titanium alloys oxygen metal injection molding powder metallurgy

Tuning Metallic Co0.85Se Quantum Dots/Carbon Hollow Polyhedrons with Tertiary Hierarchical Structure for High-Performance Potassium Ion Batteries

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Nano-Micro Letters 2019年第4期11卷 660-673页

作者： Zhiwei Liu Kun Han Ping Li Wei Wang Donglin He Qiwei Tan Leying Wang Yang Li mingli qin Xuanhui Qu Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology Beijing100083 BeijingPeople’s Republic of China Beijing Key Laboratory of Bio-inspired Energy Materials and Devices School of Space and EnvironmentBeihang University100191 BeijingPeople’s Republic of China Department of Chemical Engineering Polytechnique MontrealMontrealQC H3C 3A7Canada

Potassium-ion batteries(KIBs)are a potential candidate to lithium-ion batteries(LIBs)but possess unsatisfactory capacity and rate ***,the metallic cobalt selenide quantum dots(Co0.85Se-QDs)encapsulated in mesoporous carbon matrix were designed via a direct hydrothermal ***,the cobalt selenide/carbon composite(Co0.85Se-QDs/C)possesses tertiary hierarchical structure,which is the primary quantum dots,the secondary petals flake,and the tertiary hollow micropolyhedron ***0.85Se-QDs are homogenously embedded into the carbon petals flake,which constitute the hollow polyhedral *** unique structure can take the advantages of both nanoscale and microscale features:Co0.85Se-QDs can expand in a multidimensional and ductile carbon matrix and reduce the K-intercalation stress in particle dimensions;the micropetals can restrain the agglomeration of active materials and promote the transportation of potassium ion and *** addition,the hollow carbon framework buffers volume expansion,maintains the structural integrity,and increases the electronic *** from this tertiary hierarchical structure,outstanding K-storage performance(402 mAh g?1 after 100 cycles at 50 mA g?1)is obtained when Co0.85Se-QDs/C is used as KIBs *** importantly,the selenization process in this work is newly reported and can be generally extended to prepare other quantum dots encapsulated in edge-limited frameworks for excellent energy storage.

关键词： Cobalt selenides Quantum dots Potassium-ion batteries Tertiary hierarchical structure Hollow dodecahedron

Ecological thresholds of phytoplankton community across environmental gradients in the harmful algal blooms-frequently-occurring,subtropical coastal waters,East China Sea

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Acta Oceanologica Sinica 2021年第6期40卷 100-110页

作者： Ran Ye Chunying Ge Qiong Wang qing Xu Guofeng Xu Yongkang Yan mingli qin Yanhong Cai Yuejun Fei Marine Environmental Monitoring Centre of Ningbo Ningbo 315012China

Phytoplankton communities can response immediately and directly to environmental changes,and thus have been applied as reliable biotic indicators in aquatic *** study provided insights into the relationships concerning ecological thresholds of phytoplankton communities and individual taxon in response to environmental changes in coastal waters of northern Zhejiang Province,East China *** demonstrated that there existed seasonal variations of phytoplankton community ecological thresholds of which spring being higher than those in *** for individual species,Prorocentrum donghaiense and Noctiluca scintillans were identified as the most tolerant and sensitive indicator species in spring and summer,*** exhibited strong indications in response to environmental *** findings highlighted that phytoplankton community structure in this region was stable when environmental gradients were below the thresholds of sensitive species,whereas potential harmful algal blooms may occur when environmental gradients exceeded the thresholds of tolerant species.

关键词： ecological thresholds phytoplankton community environmental gradients indicator species coastal waters of northern Zhejiang Province

Resolving the sintering conundrum of high-rhenium tungsten alloys

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Journal of Materials Science & Technology 2023年第35期166卷 78-85页

作者： Zhongyou Que Xingyu Li Lin Zhang Xuanhui Qu Zichen Wei Chenguang Guo Haishen Sun mingli qin Gang Chen Peinan Du Yanhao Dong Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610213China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Tungsten-rhenium(W-Re)alloys with high-Re contents are the preferred refractory metal materials in many applications because of the improved ductility and processability over pure W and low-Re tung-sten ***,the sintering concurrently becomes increasingly more difficult with increasing Re *** we proposed that the sintering conundrum is caused by the lowered crystal symmetry and the wider dihedral angle distribution when body-center-cubic(BCC)W is alloyed with more hexagonal-close-packed(HCP)Re,which results in inefficient pore removal in the final stage *** showed that the conundrum can be resolved by pressureless two-step sintering(TSS)which suppresses acceler-ating final-stage grain growth,and our proposal is supported by the data of the critical densityρc that is required to start the second step for successful TSS at different W-Re *** ultrafine-grained W-Re alloys with∼300 nm average grain size and up to 25 wt%Re were successfully *** work demonstrates the unique opportunities offered by two-step sintering to advance the scientific understanding and technological practices in powder metallurgy and related fields.

关键词： W-Re alloys Two-step sintering Grain growth Ultrafine-grained materials