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Microstructures and mechanical properties of laser-directed energy deposited CrCoNi medium-entropy alloy

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Rare Metals 2024年第7期43卷 3286-3300页

作者： Wen-Jie Zhao Chang-Yu Liu Peng-Cheng Che Zhi-Liang Ning Hong-Bo Fan jian-fei sun Yong-jiang Huang Alfonso H.W.Ngan National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Space Environment Simulation Research Infrastructure Harbin Institute of TechnologyHarbin 150001China Department of Mechanical Engineering The University of Hong KongHong Kong 999077China

The distinctive intrinsic heat treatment(IHT)originating from cyclic reheating in the laser-directed energy deposition(LDED) has attracted growing attention in recent *** this investigation,simulations and experimental characterizations were performed to examine the impact of IHT on the micros true ture and mechanical properties of LDED-fabricated CrCoNi medium-entropy alloy(MEA).The results show that the intensity of the IHT is proportional to the utilized laser energy density(LED).As the LED increased,significant dynamic recrystallization and grain refinement occurred within the alloy due to the enhanced intensity of ***,the high LED leads to severe hot cracking within the as-built MEA,resulting in inferior *** decreasing LED,the hot cracking was effectively ***,low LED weakened the intensity of IHT and consequently inhibited kinetic conditions of dynamic recrystallization,resulting in a heterogeneous grain structure characterized by multi-scale-sized *** structure provides significant hetero-deformation-induced hardening during plastic deformation,enabling the alloy to have a sustainable work-hardening *** expect that this work will have implications in taking full advantage of the unique IHT of the LDED process to fabricate ME As with excellent metallurgical quality and mechanical performance.

关键词： Intrinsic heat treatment Laser-directed energy deposition CrCoNi MEA Dynamic recrystallization Heterogeneous grain structure

Microstructure and mechanical properties of twin-wire arc sprayed Ni-Al composite coatings on 6061-T6 aluminum alloy sheet

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International Journal of Minerals,Metallurgy and Materials 2014年第5期21卷 469-478页

作者： Ji-xiao Wang Jing-shun Liu Lun-yong Zhang jian-fei sun Zhi-ping Wang School of Materials Science and Engineering Harbin Institute of Technology Harbin Welding Institute China Academy of Machinery Science & Technology School of Materials Science and Engineering Inner Mongolia University of Technology National Laboratory of Solid State Microstructures & Department of Materials Science and Engineering Nanjing University College of science Civil Aviation University of China

We have systematically studied the microstructure and mechanical properties of Ni-5wt%Al and Ni-20wt%Al composite coat- ings fabricated on 6061-T6 aluminum alloy sheet by twin-wire arc spraying under different experimental conditions. The abrasive wear be- havior and interface diffusion behavior of the composite coatings were evaluated by dry/wet rubber wheel abrasive wear tests and heat treat- ment, respectively. Experimental results indicate that the composite coatings exhibit features of adhesive wear. Besides, the Vickers micro- hardness of NiA1 and Ni3AI intermetallic compounds is relatively larger than that of the substrate, which is beneficial for enhancing the wear resistance. With the increase of annealing temperature and time, the interface diffusion area between the Ni-Al coating and the substrate gradually expands with the formation of NiAl3 and Ni2Al3 phases, and is controlled by diffusion of aluminum atoms. The grain growth ex- ponent n of diffusion kinetics of the Ni-Al coating, calculated via a high-temperature diffusion model at 400, 480, and 550℃, is between 0.28 and 0.38. This satisfies the cubic law, which is consistent with the general theoretical relationship of high-temperature diffusion.

关键词： composite coatings intermetallics spraying aluminum alloys mechanical properties diffusion

Mechanical property statistical analysis of Gd50Al30Co20 amorphous wires for providing reference to design requirements of cooling system

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Journal of Iron and Steel Research International 2018年第3期25卷 261-267页

作者： Bin Luo Hong-xian Shen Lin Lin Hai-chao Li Da-wei Xing jian-fei sun School of Mechatronics Engineering Harbin Institute ofTechnology Harbin 150001 Heilongjiang China School of Materials Science and Engineering HarbinInstitute of Technology Harbin 150001 Heilongjiang China

Gd50Al3oCo20 wires show excellent magnetocaloric properties and high heat exchange rate due to the microsize. The Weibull and lognormal methods were used for systematically analyzing its mechanical properties for matching the design requirements in cooling system. The wire exhibits average fracture strength of-969.5 MPa and typical fracture behavior of amorphous character. Moreover, the distributions of stresses for tensile strains at 10 values are estimated by probability plot and Chi-square goodness-of-fit test. The random stresses were best fitted by lognormal probability distribution for most studied cases; however, fracture strength was best fitted by Weibull probability distribution. It is interesting to note that the mean and standard deviation of the stresses （to reach specific tensile strain） increase as the tensile strain grows, accompanied by the coefficients of variation of stresses which decrease smoothly. It is concluded that the inhomogeneity of material does cause the scatter of stresses growth, and the scatter could be considerably large.

关键词： Gd50Al30Co20 amorphous wire Tensile property Statistical analysis Variation coefficient

Frequency dependence of magnetization and giant magneto impedance effect of amorphous wires

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International Journal of Minerals,Metallurgy and Materials 2013年第4期20卷 375-378页

作者： Shu-ling Zhang jian-fei sun Da-wei Xing Da-qing Fang Lu-cai Wang School of Materials Science and Engineering Taiyuan University of Science and Technology School of Materials Science and Engineering Harbin Institute of Technology

The frequency dependence of magnetization process and giant magneto impedance （GMI） effect of Co-rich melt-extracted amorphous wires was studied by Kerr effect and impedance analyzer, respectively. It is demonstrated that the transverse Kerr intensity and the corresponding GMI response increase with increasing frequency, which contributes to the upgraded skin effect. However, the skin depth has a slothful trend with frequency when it is up to the megahertz range, which gives rise to the transformation of magnetization. The process is much more sensitive to the direct current magnetic field and the sensitive change of the circular permeability, and GMI response is observed as its consequence. This proves that the evolution of circumferential magnetization and the corresponding permeability with the direct current magnetic field is the essence of GMI response, and a much more sensitive magnetization promises a better GMI response.

关键词： amorphous wires magnetization giant magneto impedance Kerr magneto-optical effect melt extraction

Microstructure Evolution and Mechanical Properties of Spray-deposited Al-21.47Si-4.73Fe-2.5Cu-0.9Mg Alloy

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Journal of Iron and Steel Research International 2016年第1期23卷 14-18页

作者： Yan-dong JIA Fu-yang CAO Pan MA Jing-shun LIU jian-fei sun Gang WANG Laboratory for Microstructures Institute of MaterialsShanghai University School of Materials Science and Engineering Harbin Institute of Technology School of Materials Engineering Shanghai University of Engineering Science School of Materials Science and Engineering Inner Mongolia University of Technology

Al-Si-Fe-Cu-Mg alloy was prepared by spray deposition and was further processed by hot extrusion as well as *** results indicate that the microstructure of the deposited alloy is composed of primary Si particles with average size of less than 5μm,α-Al,Al_2CuMg,β-Al_5FeSi andδ-Al_4FeSi_2（rectangular shape）,and no eutectic silicon is found due to the special solidification *** age hardening curves reveal two *** uniform ultimate tensile strength（UTS）and the elongation of the peak-aged Al-Si-Fe-Cu-Mg alloy are 468.3 MPa,0.61% at 298 Kand 267.4MPa,6.42% at 573 K,*** fracture surfaces display brittle fracture morphology at 298 K,whereas it varies to mixture of brittle and ductile failure with increasing the temperature.

关键词： spray deposition hypereutectic Al-Si alloy microstructure aging mechanical property

A DFT study on Pt single atom loaded COF for efficient photocatalytic CO_(2)reduction

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Journal of Materials Science & Technology 2024年第3期170卷 87-94页

作者： fei Xie Chuanbiao Bie jian sun Zhenyi Zhang Bicheng Zhu Laboratory of Solar Fuel Faculty of Materials Science and ChemistryChina University of GeosciencesWuhan430078China Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission Key Laboratory of Photosensitive Materials and Devices of Liaoning ProvinceSchool of Physics and Materials EngineeringDalian Minzu UniversityDalian116600China

Photocatalytic CO_(2)reduction provides a promising strategy for the alleviation of greenhouse effect and energy shortage *** single atom modification is an effective method to improve the CO_(2)reduction performance of covalent organic framework(COF)photocatalysts,while the intrinsic mechanism is not revealed in ***,a Pt-COF photocatalytic system was constructed by embedding Pt single atom in TFPT-TMT-COF(TFPT:1,3,5-tris(4-formylphenyl)-triazine,TMT:2,4,6-trimethyl-1,3,5-triazine).Based on density functional theory(DFT)calculation,the geometric structure and electronic property of Pt-COF were investigated,and the CO_(2)adsorption and reduction reaction process on Pt-COF were *** results show that the Pt atom can be steadily anchored in COF via the formation of Pt-N and Pt-C ***,there is strong electronic interaction between Pt and *** incorporation of Pt atom benefits the CO_(2)reduction activity of COF from multiple aspects:(ⅰ)reducing the band gap and improving light absorption;(ⅱ)enhancing CO_(2)adsorption and activating the CO_(2)molecule;(ⅲ)decreasing the energy barrier in the hydrogenation step of CO_(2)→COOH,thus facilitating CO_(2)conversion to CO;(ⅳ)inhibiting the hydrogenation of CO,thereby increasing the selectivity of *** work brings a novel insight into the excellent CO_(2)reduction performance of Pt modified COF,and provides useful references for the design of single atom photocatalysts.

关键词： Photocatalysis Carbon dioxide reduction Covalent organic framework Pt single atom Theoretical calculation

High temperature deformation behavior and processing map of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders

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Journal of Iron and Steel Research International 2017年第4期24卷 435-441页

作者： Ying Bao Dong-ye Yang Na Liu Guo-qing Zhang Zhou Li Fu-yang Cao jian-fei sun School of Materials Science and Engineering Harbin Institute of Technology School of Materials Science and Engineering Harbin University of Science and Technology Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperature range of 1323-1473 Kand strain rate range of 0.001-0.5s^（-1）.The calculated activation energy in the above variational ranges of temperature and strain rate possesses a low activation energy value of approximately 365.6kJ/mol based on the constitutive relationship models developed with the Arrhenius-type constitutive model respectively considering the strain rate and deformation *** hot working flow behavior during the deformation process was analyzed combined with the microstructural ***,the processing maps during the deformation process were established based on the dynamic material model and Prasad instability criterion under different deformation ***,the optimal hot processing window of this alloy corresponding to the wide temperature range of 1353-1453 Kand the low strain rate of 0.001-0.1s^（-1） was obtained.

关键词： Hot compressive deformation TiAl alloy Constitutive equation Processing map Gas atomization Hot isostatic pressing

Crystallization of a Ti-based Bulk Metallic Glass Induced by Electropulsing Treatment

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Journal of Iron and Steel Research International 2016年第1期23卷 69-73页

作者： Yong-jiang HUANG Xiang CHENG Hong-bo FAN Shi-song GUAN Zhi-liang NING jian-fei sun National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of Technology School of Materials Science and Engineering Harbin Institute of Technology

The effect of electropulsing treatment（EPT）on the microstructure of a Ti-based bulk metallic glass（BMG）has been *** maximum current density applied during EPT can exert a crucial role on tuning the microstructure of the *** the maximum current density is no more than 2 720A/mm^2,the samples retains amorphous nature,whereas,beyond that,crystalline phases precipitate from the glassy *** EPT,the maximum temperature within the samples EPTed at the maximum current densities larger than 2 720A/mm^2 is higher than the crystallization temperature of the BMG,leading to the crystallization event.

关键词： bulk metallic glass electropulsing transmission electron microscopy crystallization microstructure

Giant magneto-impedance effect of two paralleled amorphous microwires

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Rare Metals 2016年第4期35卷 344-348页

作者： Shu-Ling Zhang Yue-Sheng Chai Da-Qing Fang Lu-Cai Wang Da-Wei Xing jian-fei sun School of Materials Science and Engineering Taiyuan University of Science and Technology School of Materials Science and Engineering Harbin Institute of Technology

Giant magneto-impedance （GMI） is effectively enhanced by the mutual magnetic interaction between two amorphous microwires. A comparative study on GMI properties of a single wire and two wires arranged in par- allel mode was reported in this work. Two-peak （TP） of impedance characteristic is presented when the dc external field changed from 0 to 320 A,m-＇ in two-wire system, which is attributed to successive magnetization process in two wires induced by their magnetic interaction. And the evolution of single peak to TP phenomenon, when the distance between two wires is upto 8 ram, evidences a distance dependence of transformation from successive magnetization to simultaneous via a corresponding dis- tance dependence of magnetostatic interactions. It is pro- posed that the recombination of magnetic interaction and the shielding effect results in a distance dependency of GMI response. When the distance is 8 ram, the magneti- zation process is close to synchronous between two wires, which give rises to higher circular permeability and better GMI response. The impedance ratio AZ/Z increases from 74.5 % of single wire to 172.4 % at 10 MHz. However, when the distance is upto 12 mm, the magnetic interaction is weak and magnetization process is completely independent, and GMI response decreases, relatively. This indicates that the GMI response could be effectively improved in a two-wire connection with an optical distance, which is promising and useful for the application of high-performance GMI sensors.

关键词： Amorphous microwire Magnetic interaction Giant magneto-impedance Magnetization