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Journal of Materials Science & Technology 2021年第31期90卷 150-158页

作者： Tao Xiang Zeyun Cai Peng Du Kun Li Zongwei Zhang Guoqiang Xie School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Super-high strength NbTaTiZr high-entropy alloys(NbTaTiZr HEAs)have been successfully fabricated by the mechanical alloying(MA)with spark plasma sintering(SPS)technology,which is 2-fold compared with that of NbTaTiZr HEAs prepared by vacuum arc melting(VAM).After the SPS process,the bulk NbTaTiZr alloy samples are provided with dual-phase body-centered cubic(BCC)structure and nanoscale grain size about 500 nm that is obviously smaller than that of NbTaTiZr HEA fabricated by VAM.When the sintering temperature is 800℃,the compressive fracture strength is the highest reaching at 2511±78 MPa.When the sintering temperature is 1000℃,the fracture strain is the highest reaching at 12.8%,and compressive fracture strength and yield strength also reach at 2274±91 MPa and 2172±47 MPa,respectively.The excellent mechanical properties of bulk NbTaTiZr alloy samples are attributed to the merits of MA and SPS,and the collaboration effect of ultra-fine grains strengthening,solid solution strengthening and interstitial solid solution strengthening.

关键词： NbTaTiZr high-entropy alloys mechanical alloying Ultra-fine grain Spark plasma sintering mechanical properties Corrosion behavior

Effect of CeH_(2.29) on the microstructures and hydrogen properties of LiBH_4-Mg_2NiH_4 composites

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International Journal of Minerals,Metallurgy and Materials 2015年第4期22卷 423-428页

作者： Xin Zhao Shu-min Han Yuan Li Xiao-cui Chen Dan-dan Ke Hebei Key Laboratory of Applied Chemistry College of Environmental and Chemical Engineering Yanshan University State Key Laboratory of Metastable Materials Science and Technology Yanshan University

A composite of LiBH4-Mg2NiH4 doped with 10wt% CEH2.29 was prepared by ball milling followed by dynamic interspace vac- uum treatment at 573 K. The introduction of CEH2.29 caused a transformation in the morphology of Mg from complex spongy and lamellar to uniformly spongy, resulting in refined particle size and abundant H diffusion pathways. This LiBH4-Mg2NiH4 ＋ 10wt% CEH2.29 composite exhibited excellent hydrogen storage properties. The starting temperature of rapid H absorption decreased to 375 K in the doped composite from 452 K for the unmodified material, and the onset decomposition temperature of its hydride was reduced from 536 K to 517 K. In addi- tion, the time required for a hydrogen release of 1.5wt% （at 598 K） was 87 s less than that of the un-doped composite.

关键词： hydrogen storage materials cerium hydride mechanical alloying microstructure

Ultrahigh electrical conductivities and low lattice thermal conductivities of La,Dy,and Nb Co-doped SrTiO3 thermoelectric materials with complex structures

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Journal of Materials Science & Technology 2020年第17期52卷 172-179页

作者： Daquan Liu Yanxia Wang Xue Jiang Huijun Kang Xiong Yang Xiaoying Zhang Tongmin Wang Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Key Laboratory of Material Modification by Laser Ion and Electron Beams(Dalian University of Technology)Ministry of EducationDalian116024China

Microstructural modifications and appropriate element doping are necessary to simultaneously enhance the electrical conductivities and reduce the lattice thermal conductivities of thermoelectric materials.Herein,we propose a strategy of multielement doping combined with a burial sintering process to promote thermoelectric properties.Three-element doped Sr0.9La0.05Dy0.05Ti1-xNbxO3(x=0,0.05,0.10,0.15,and 0.20)powders were synthesized by high-energy ball milling,and corresponding bulk samples were prepared by carbon burial sintering.In the bulk samples,we obtained the desired microstructures composed of shell-vesicular architectures with dense dislocations and second phase particles.These materials had ultrahigh electrical conductivities(~5300 S cm^-1 at 300 K),low lattice thermal conductivities(~1.6 Wm^-1 K^-1 from 700 to 1100 K when x=0.2)and low total thermal conductivities(minimum value of 2.95 Wm^-1 K^-1 when x=0.05 at 1100 K).The maximum zT values were 0.28 when x=0.05 and 0.27 when x=0.2 at 1100 K.This strategy provides a possible direction for improving the thermoelectric properties of SrTiO3 based materials.

关键词： Strontium titanate mechanical alloying Thermoelectric material Dense dislocation Sintering process

Thermal Properties of Ni–Cr–Si–B–Fe Based Interlayer Material and Its Application in TLP Bonding of IN 718 Superalloy

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Acta Metallurgica Sinica(English Letters) 2020年第12期33卷 1666-1680页

作者： U.K.Tarai P.S.Robi Sukhomay Pal Department of mechanical Engineering IIT GuwahatiGuwahati 781039India

A new Ni–Cr–Si–B–Fe fi ller material is prepared for transient liquid-phase(TLP)bonding of Inconel 718 superalloy by mechanical alloying technique.The melting temperature range of the fi ller material and its activation energy of melting are determined by diff erential scanning calorimetry technique.The activation energy and melting temperature of the alloy powder decrease with increasing milling time.Inconel 718 alloy was joined via TLP by using the newly developed fi ller material.The eff ect of TLP bonding temperature and time on microstructural evolution and mechanical properties of the joint was investigated.Three distinct microstructural regions were observed in the bonding area:isothermal solidifi cation zone consisting of a single-phase solid solution,diff usion aff ected zone consisting of extensive diff usion-induced precipitates of metallic boride,and unaff ected base material.The ultimate shear strength and microhardness of the TLP-bonded joint increase with bonding time and temperature.

关键词： Transient liquid-phase(TLP)bonding Kissinger plot mechanical alloying Inconel 718

Effect of milling atmosphere on structural and magnetic properties of Ni-Zn ferrite nanocrystalline

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Chinese Physics B 2015年第4期24卷 481-490页

作者： Abdollah Hajalilou Mansor Hashim Reza Ebrahimi-Kahrizsangi Mohamad Taghi Masoudi Material Synthesis and Characterization Laboratory Institute of Advanced Technology (ITMA)Universiti Putra Malaysia Advanced Materials Research Center Materials Engineering Department Najafabad Branch Islamic Azad University

Powder mixtures of Zn, NiO, and Fe2O3 are mechanically alloyed by high energy ball milling to produce Ni-Zn ferrite with a nominal composition of Ni0.36Zn0.64Fe2O4. The effects of milling atmospheres （argon, air, and oxygen）, milling time （from 0 to 30 h） and heat treatment are studied. The products are characterized using x-ray diffractometry, field emission scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and transmitted electron microscopy. The results indicate that the desired ferrite is not produced during the milling in the samples milled under either air or oxygen atmospheres. In those samples milled under argon, however, Zn/NiO/Fe2O3 reacts with a solid-state diffusion mode to produce Ni-Zn ferrite nanocrystalline in a size of 8 nm after 30-h-milling. The average crystallite sizes decrease to 9 nm and 10 nm in 30-h-milling samples under air and oxygen atmospheres, respectively. Annealing the 30-h-milling samples at 600℃ for 2 h leads to the formation of a single phase of Ni-Zn ferrite, an increase of crystallite size, and a reduction of internal lattice strain. Finally, the effects of the milling atmosphere and heating temperature on the magnetic properties of the 30-h-milling samples are investigated.

关键词： Ni-Zn ferrite nanocrystalline mechanical alloying milling atmosphere milling time magnetic property

Microstructure and mechanical properties of ultra-fine grained MoNbTaTiV refractory high-entropy alloy fabricated by spark plasma sintering

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Journal of Materials Science & Technology 2019年第11期35卷 2600-2607页

作者： Qing Liu Guofeng Wang Xiaochong Sui Yongkang Liu Xiao Li Jianlei Yang National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology

The MoNbTaTiV refractory high-entropy alloy(RHEA)with ultra-fine grains and homogeneous microstructure was successfully fabricated by mechanical alloying(MA)and spark plasma sintering(SPS).The microstructural evolutions,mechanical properties and strengthening mechanisms of the alloys were systematically investigated.The nanocrystalline mechanically alloyed powders with simple bodycentered cubic(BCC)phase were obtained after 40 h MA process.Afterward,the powders were sintered using SPS in the temperature range from 1500℃to 1700℃.The bulk alloys were consisted of submicron scale BCC matrix and face-centered cubic(FCC)precipitation phases.The bulk alloy sintered at 1600℃had an average grain size of 0.58μm and an FCC precipitation phase of 0.18μm,exhibiting outstanding micro-hardness of 542 HV,compressive yield strength of 2208 MPa,fracture strength of 3238 MPa and acceptable plastic strain of 24.9%at room temperature.The enhanced mechanical properties of the MoNbTaTiV RHEA fabricated by MA and SPS were mainly attributed to the grain boundary strengthening and the interstitial solid solution strengthening.It is expectable that the MA and SPS processes are the promising methods to synthesize ultra-fine grains and homogenous microstructural RHEA with excellent mechanical properties.

关键词： Refractory high-entropy alloy Ultra-fine grain mechanical alloying Spark plasma sintering mechanical properties

Fabrication and Characterization of FeNiCr Matrix-TiC Composite for Polishing CVD Diamond Film

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Journal of Materials Science & Technology 2009年第3期25卷 319-324页

作者： Zhuji Jin Zewei Yuan Renke Kang Boxian Dong Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education Dalian University of Technology Dalian 116024 China

Dynamic friction polishing （DFP） is one of the most promising methods appropriate for polishing CVD diamond film with high efficiency and low cost. By this method CVD diamond film is polished through being simply pressed against a metal disc rotating at a high speed utilizing the thermochemical reaction occurring as a result of dynamic friction between them in the atmosphere. However, the relatively soft materials such as stainless steel, cast iron and nickel alloy widely used for polishing CVD diamond film are easy to wear and adhere to diamond film surface, which may further lead to low efficiency and poor polishing quality. In this paper, FeNiCr matrix-TiC composite used as grinding wheel for polishing CVD diamond film was obtained by combination of mechanical alloying （MA） and spark plasma sintering （SPS）. The process of ball milling, composition, density, hardness, high-temperature oxidation resistance and wear resistance of the sintered piece were analyzed. The results show that TiC was introduced in MA-SPS process and had good combination with FeNiCr matrix and even distribution in the matrix. The density of composite can be improved by mechanical alloying. The FeNiCr matrix-TiC composite obtained at 1273 K was found to be superior to at 1173 K sinterin8 in hardness, high-temperature oxidation resistance and wearability. These properties are more favorable than SUS304 for the preparation of high-performance grinding wheel for polishing CVD diamond film.

关键词： CVD diamond film FeNiCr matrix-TiC composite Spark plasma sintering mechanical alloying

Microstructures and mechanical properties of nanocrystalline NiTi intermetallics formed by mechanosynthesis

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International Journal of Minerals,Metallurgy and Materials 2018年第1期25卷 80-87页

作者： S.Arunkumar P.Kumaravel C.Velmurugan V.Senthilkumar Vinayaka Mission's Kimpananda Variyar Engineering College Salem 636308TamilnaduIndia Institute of Road and Transport Technology Erode 638316TamilnaduIndia National Institute of Technology Trichy 620015TamilnaduIndia

The formulation of nanocrystallinc NiTi shape memory alloys has potential effects in mechanical stimulation and medical im- plantology. The present work elucidates the effect of milling time on the product＇s structural characteristics, chemical composition, and mi- crohardness for NiTi synthesized by mechanical alloying for different milling durations. Increasing the milling duration led to the formation of a nanocrystalline NiTi intermetallic at a higher level. The formation of nanocrystalline materials was directed through cold fusion, fractur- ing, and the development of a steady state, which were influenced by the accumulation of strain energy. In the morphological study, uninter- rupted cold diffusion and fracturing were visualized using transmission electron microscopy. Particle size analysis revealed that the mean particle size was reduced to -93 μm after 20 h of milling. The mechanical strength was enhanced by the formation of a nanocrystalline in- termetallic phase at longer milling time, which was confirmed by the results of Vickers hardness analyses.

关键词： nickel-titanium shape memory alloy lattice strain nano-crystalline mechanical alloying microstructural characterization

Microstructure and mechanical Behavior of FeNiCoCr and FeNiCoCrMn High-Entropy Alloys Fabricated by Powder Metallurgy

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Acta Metallurgica Sinica(English Letters) 2021年第4期34卷 445-454页

作者： Chenliang Chu Weiping Chen Zhen Chen Zhenfei Jiang Hao Wang Zhiqiang Fu Guangdong Key Laboratory for Advanced Metallic Materials Processing South China University of TechnologyGuangzhou 510640China Shantou Technician College Shantou 515041China

The present work reports a systematic investigation on phase evolution,microstructure and microstructure-property relationship of two typical face-centered cubic(FCC)structured high-entropy alloys(HEAs),FeNiCoCr and FeNiCoCrMn,prepared via mechanical alloying(MA)followed by spark plasma sintering(SPS).Following 50 h of MA,the two HEAs consisted of a mixture of FCC and body-centered cubic phases.Following SPS,the bulk FeNiCoCr alloy showed a primary FCC phase with a small amount of Cr_(23)C_(6) and Cr_(2)O_(3) contaminants,while the bulk FeNiCoCrMn alloy was composed of a primary FCC phase with some(Cr,Mn)23C6 and MnCr_(2)O_(4) contaminants.The average grain size of the primary FCC phase in the bulk FeNiCoCr alloy was~416 nm,while that of the primary FCC phase in the bulk FeNiCoCrMn alloy was~547 nm.The yield strength,compressive strength and strain-to-failure of the bulk FeNiCoCr alloy are 1525 MPa,1987 MPa and 24.4%,respectively,whereas those of the bulk FeNiCoCrMn alloy are 1329 MPa,1761 MPa and 21.9%,respectively.It suggests that the bulk FeNiCoCrMn exhibited lower strength and plasticity in comparison with the bulk FeNiCoCr alloy.Clearly,the smaller grain size of the primary FCC phase in the FeNiCoCr alloy is mainly responsible for the better mechanical performance.

关键词： High-entropy alloy mechanical alloying Microstructure Strengthening Contaminants

Sintering Behavior and Microstructure Evolution of mechanically Alloyed W-Bronze Composite Powders by Two-step Ball Milling Process

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Journal of Materials Science & Technology 2013年第1期29卷 59-69页

作者： Kahtan S. Mohammed Azmi Rahmat Khairel R. Ahmad School of Materials Engineering Universiti Malaysia Perlis

The miscibility of W in Sn and Cu is extremely poor. Sintering of W-bronze composites to their full density is proved to be difficult. To tackle this problem, the ball milling process of the W-bronze powder mixture proposed in this study was split into two steps. In the first step, the softness of Sn powder was exploited to modify the surface morphology of W particles. In the second step, Cu was added to the ball milled mixture. To achieve this goal, four 50 wt% W-bronze compact sets of different powder precursors and activator additions were produced. The sintering process was performed at 1150 ℃. The two-step ball milled powder yielded sintered compacts of homogeneous microstructure of fine polygonal W grains dispersed in bronze matrix. They showed the highest hardness and densification levels. The sintered density, microstructure, hardness and densification mechanisms of the sintered compacts were investigated, examined and evaluated using different metallographic, microscopic and measurement facilities.

关键词： Metal matrix composites mechanical alloying Sintering Microstructure Scanning electron microscopy