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Study on absorption coefficients of dual-energy γ-rays in determining phase fractions of multiphase flows

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第12期6卷 1416-1419页

作者：李志彪李东晖吴应湘 Institute of Mechanics Chinese Academy of Sciences Graduate School Chinese Academy of Sciences Beijing 100080 China

This paper discusses the principle and mathematical method to measure the phase fractions of multiphase flows by using a dual-energy gamma-ray system. The dual-energy gamma-ray device is composed of radioactive isotopes of 241Am and 137Cs with emission energies of 59.5 keV and 662 keV respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The statistical error has been analyzed on the basis of the accurate absorption coefficient which enables determination phrase fractions almost independent of the flow regime. Improvement has been achieved on the measurement accuracy of phase fractions.

关键词： Absorption coefficient γ-rays Dual-energy phase fraction

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High magnetic energy product in isotropic nanocomposite powders with high percent of soft phase towards ultrastrong magnets

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Journal of Materials Science & Technology 2023年第13期144卷 161-167页

作者： Longfei Ma Wei Quan Jinkui Fan Yanbai Chen Qiang Zheng Baoru Bian Jian Zhang Juan Du Institute of Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China Ningbo Institute of Material Technology&Engineering Chinese Academy of SciencesNingbo 315201China

Nanostructure of magnetically hard and soft materials is fascinating for exploring next-generation ul-trastrong permanent magnets with less expensive rare-earth ***,the resulting hard/soft nanocomposites often exhibit a low remanence/energy product due to the challenge in obtaining ideal phase components and appropriate soft phase *** this work,a novel microstructure of multiple phases consisting of 1:5 phase and 1:3 phase as main hard phase,and a high ratio of Fe(Co)(27 wt.%-48 wt.%)as soft phase was obtained in Sm-Co(Fe)/Fe nanocomposite *** grain size of both hard and soft phases below 15 nm was *** optimal energy product for Sm-Co(Fe)/Fe(Co)nanocom-posite is 2.1 times(an increment of 107%)of the corresponding single-hard-phase powders without soft *** reports that the isotropic nanocomposite powders exhibit a record of magnetic energy product larger than 25 MGOe(the highest value is 28.6 MGOe).The high performance and the microstructure achieved in this work for the isotropic powders will shed light on and provide a good premise for syn-thesizing high performance anisotropic bulk nanocomposite magnets.

关键词： Nanocomposite Sm-Co(Fe)/Fe(Co) Microstructure phase composition phase fraction Magnetic energy product

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Microstructural evolution and mechanical properties of Nb-Si-Cr ternary alloys with a tri-phase Nb/Nb5Si3/Cr2Nb microstructure fabricated by spark plasma sintering

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Progress in Natural Science:Materials International 2018年第5期28卷 626-634页

作者： Shasha Zhang Wei Liu Jiangbo Sha School of Materials Science and Engineering Beihang University Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials

In this work,pure Nb,Nb;Si;and Laves Cr;Nb compound powders were used as raw materials to prepare Nb-SiCr ternary alloys by spark plasma sintering（SPS）.A comprehensive estimation of the microstructure and properties,including room temperature fracture toughness,high temperature strength and oxidation resistance,of the Nb-Si-Cr ternary alloys as a function of the Nb/Nb;Si;/Cr;Nb phase volume fraction combinations was *** results showed that Nb-Si-Cr ternary samples with the relative density larger than 98.42% were obtained by SPS processing,and the samples all consisted of Nb,Nb;Si;and Cr;Nb phases that were distributed *** fracture toughness K;of the Nb/Nb;Si;/Cr;Nb microstructure,which was dominated by the Nb phase,naturally increased with the Nb *** expected,the room-temperature Vickers hardness and the high-temperature strength of the bulk alloys increased monotonically with the increasing of the stiffening Nb;Si;***,the binary Cr;Nb phase played a positive role in the high temperature strength and oxidation ***,the fracture modes of the typical Nb/Nb;Si;/Cr;Nb microstructures under bending and compression conditions at room and high temperatures as well as the oxidation mechanism are described and discussed.

关键词： Nb-Si Alloy Spark Plasma Sintering(SPS) phase fraction Fracture Toughness High-Temperature Strength

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Microstructure and mechanical properties of Nb-Si alloys fabricated by spark plasma sintering

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Progress in Natural Science:Materials International 2013年第1期23卷 55-63页

作者： Wei Liu Yongming Fu Jiangbo Sha School of Materials Science and Engineering Beihang University37 Xueyuan Road

This paper deals with microstructural evolutions and mechanical properties of Nb-Si binaries containing dual-phase Nb/Nb5Si3 with Nb to Nb5Si3 fraction ratios of 90:10,80:20,70:30 and 50:50,prepared by spark plasma sintering(SPS).Dense Nb/Nb5Si3 samples with a relative density larger than 99.5% were obtained by SPS *** SPS samples consist of the Nb and Nb5Si3 phases with less than 3% fraction of NbO *** at room temperature,and compressive strength at 1150℃ and 1250 1C of the bulk SPS alloys increase monolithically by enhancing fraction of the stiffening Nb5Si3 *** example,0.2% yield strength,σ0.2,increases from 175 MPa to 420 MPa at 1150℃ and from 110 MPa to 280 MPa at 1250℃,when the Nb5Si3 fraction increases from 10% to 50%.It is interesting that the fracture toughness,KQ,of the bulk SPS samples seems not to be sensitive to phase *** treatment,however,plays a key role on the KQ as compared with that of the as-sintered state,at the corresponding Nb5Si3 fraction and considerably improves the KQ by about 100% for samples with the Nb5Si3 fractions of 10%-30%,and by about 50% for the sample with 50% Nb5Si3 fraction.

关键词： Nb-Si alloy Spark plasma sintering(SPS) phase fraction Fracture toughness High-temperature strength

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