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Laser powder bed fusion of NiTiFe shape memory alloy via premixed powder:microstructural evolution,mechanical and functional properties

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Rare Metals 2024年第5期43卷 2300-2316页

作者： Bo Yuan Jin-Guo Ge Liang Zhang hong-jun chen Long-Sha Wei Yu-Duo Zhou Run-Hua Song Institute of Intelligent Manufacturing Technology Shenzhen PolytechnicShenzhen 518055China School of Mechanical and Electrical Engineering Guilin University of Electronic TechnologyGuilin 541004China Guangdong Advanced Polymer Composite Engineering Technology Research Center Shenzhen Academy of Aerospace TechnologyShenzhen 518057China Jihua Laboratory Testing Center Jihua LaboratoryFoshan 528000China

High-cost pre-alloyed powder is the bottleneck problem that limits the widespread application of additivemanufactured shape memory *** this work,the lowcost ternary NiTiFe shape memory alloy is fabricated by laser powder bed fusion(LPBF)technique via mechanically mixed pre-alloy NiTi powder and varying contents pure Fe powder(1,2,3 wt%).All NiTiFe alloys show a relative density of up to 99.8%by optimizing the LPBF processing *** to the heterogeneous nucleation effect of micron-sized Fe particles,both grain refinement and texture weakening are generated in the NiTiFe alloys,accompanied by the reduction of dislocation *** the room-temperature mechanical properties,the NiTi-3Fe alloy shows the highest microhardness of HV370,but the fracture strength and elongation reduce to1701 MPa and 23%*** evolution of mechanical properties is attributed to the high internal defects,low dislocation density and the incoherent ***,the NiTi-3Fe alloy shows the quasi-linear superelasticity behavior;the superelastic recoverable strain of NiTi-1Fe and NiTi-2Fe decreased with the increase in Fe *** study provided a new-fangled insight for the development of multi-component NiTi-based shape memory alloys by additive manufacturing.

关键词： Additive manufacturing Shape memory alloy Metal matrix composite Microstructure Mechanical properties

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Formation mechanism of calcium hexaluminate

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International Journal of Minerals,Metallurgy and Materials 2016年第10期23卷 1225-1230页

作者： jun-hong chen Hai-yang chen Ming-wei Yan Zheng Cao Wen-jun Mi School of Materials Science and Engineering University of Science and Technology Beijing

To investigate the formation mechanism of calcium hexaluminate（CaAl_（12）O_（19）, CA_6）, the analytically pure alumina and calcia used as raw materials were mixed in CaO/Al_2O_3 ratio of 12.57：137.43 by mass. The raw materials were ball-milled and shaped into green specimens, and fired at 1300-1600°C. Then, the phase composition and microstructure evolution of the fired specimen were studied, and a first principle calculation was performed. The results show that in the reaction system of CaO and Al_2O_3, a small amount of CA_6 forms at 1300°C, and greater amounts are formed at 1400°C and higher temperatures. The reaction is as follows： CaO ·2Al_2O_3（CA_2）＋ 4Al_2O_3 → CA_6. The diffusions of Ca^（2＋） in CA_2 towards Al_2O_3 and Al^（3＋） in Al_2O_3 towards CA_2 change the structures in different degrees of difficulty. Compared with the difficulty of structural change and the corresponding lattice energy change, it is deduced that the main formation mechanism is the diffusion of Ca^（2＋） in CA_2 towards Al_2O_3.

关键词： calcium hexaluminate microstructural evolution first principle formation mechanisms

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High-performance chromite by structure stabilization treatment

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Journal of Iron and Steel Research International 2020年第2期27卷 169-179页

作者： En-hui Wang Chang Luo jun-hong chen Xin-mei Hou Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Chromite is an important raw material applied in *** have been made to obtain high-performance chromite by adding MgO and Al203 from the viewpoint of structure *** order to explore the effect of Al203 and MgO on the structure,two formulas,i.e.,Mg-rich and Al-rich ones,were *** phase and microstructure development of samples heated in the temperature range of 1200-1600℃ were studied by X-ray diffraction and scanning electron microscopy with energy-dispersive *** and Al203 added have diffused into chromite successfully by heat *** diffuses into chromite,occupying the tetrahedral vacancies caused by the diffusion and oxidation of Fe2+ions to stabilize the ***203 diffuses into the surface layer of chromite,forming spinel-sesquioxide ***-rich sample which has spinel-sesquioxide structure shows better corrosion resistance toward fayalite slag than Mg-rich sample which has single spinel structure by blocking the interdiffusion between Fe^2+ions in fayalite slag and Mg^2+ions in chromite.

关键词： Chromite Structure optimization Corrosion resistance Refractory

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Rapid Synthesis of Piezoelectric ZnO-Nanostructures for Micro Power-Generators

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Journal of Materials Science & Technology 2013年第10期29卷 893-897页

作者： Nai-Feng Hsu Tien-Kan Chung Ming Chang hong-jun chen Department of General Education Army Academy Department of Mechanical Engineering National Chiao Tung University Department of Mechanical Engineering Chung Yuan Christian University State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology

In this paper, we report a rapid synthesis of piezoelectric ZnO-nanostructures and fabrication of the nanostructures- based power-generators demonstrating an energy conversion from an environmental mechanical/ultrasonic energy to an electrical energy. The ZnO nanostructures are grown on a silicon wafer by a modified chemical solution method （CSD, chemical-solution-deposition） with a two-step thermal-oxidation approach. The synthesis process can be completed within 1 h. By varying the mixture-ratio of Zn micro-particles in an oxalic acid solution with 0.75 mol/l concentration in the CSD process, the growth mechanism is well-controlled to synthesize three different types of ZnO-nanostructures （i.e., dandelion-like nanostructures, columnar nanostructures, and nanowires）. Furthermore, through oxidizing at different temperatures in the thermal-oxidation process, the featured geometry of the nanostructures （e.g., the length and diameter of a nanowire） is modified. The geometry, size, morphology, crystallization, and material phase of the modified nanostructures are characterized by scanning electron microscopy and X-ray diffraction. Finally, the nanostructures are used to fabricate several micro power-generators. Through the piezoelectric effect, a maximum current density output of 0.28 μA cm-2 generated by a power-generator under an ultrasonic wave is observed.

关键词： Piezoelectric ZnO nanostructures Chemical solution method Thermal-oxidation Power-generator

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Utility of multiple endoscopic techniques in differential diagnosis of gallbladder adenomyomatosis from gallbladder malignancy with bile duct invasion: A case report

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World Journal of Clinical Cases 2020年第2期8卷 464-470页

作者： Li-Jia Wen jun-hong chen Yong-Jin chen Kai Liu Department of Hepatopancreatobiliary Surgery The First Hospital of Jilin University

BACKGROUND Gallbladder adenomyomatosis(GAM) is a benign lesion, characterized by thickening of the gallbladder wall and a focal mass, which overlap with the features of gallbladder malignancy. Consequently, differential diagnosis of GAM from gallbladder cancer is difficult and approximately 20% of suspected malignant biliary strictures are postoperatively confirmed as benign ***, we report a case in which a preoperative diagnosis of GAM was made by a combination of endoscopic and imaging *** SUMMARY A 40-year-old man was referred to our hospital chiefly for a fever and right upper abdominal pain with dark urine. Enhanced computed tomography showed thickening of the gallbladder wall and a mass in the gallbladder neck with involvement of the hepatic bile ducts, which was suspected to be *** malignancy with bile duct invasion was ruled out by subsequent endoscopic examinations, including endoscopic retrograde cholangiopancreatography, intraductal ultrasound, and Spy Glass. Endoscopic examinations showed a homogeneous hyperechoic lesion with smooth margins of benign bile duct stricture suggestive of inflammatory stenosis of the bile *** patient underwent laparoscopic cholecystectomy. GAM was postoperatively diagnosed and confirmed based on the histopathology results, which are consistent with the preoperative diagnosis. Notably, no malignant event occurred in the patient during a 12-mo follow-up *** A combination of endoscopic techniques may help in the differential diagnosis of GAM from gallbladder cancer.

关键词： Gallbladder adenomyomatosis Differential diagnosis Endoscopic retrograde cholangio-pancreatography Intraductal ultrasound SpyGlass Case report

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Microwave absorption properties of SiC@SiO2@Fe3O4 hybrids in the 2–18 GHz range

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International Journal of Minerals,Metallurgy and Materials 2017年第7期24卷 804-813页

作者： Peng Zhou jun-hong chen Meng Liu Peng Jiang Bin Li Xin-mei Hou National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing Beijing 100083 China School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing Beijing 100083 China

To enhance the microwave absorption performance of silicon carbide nanowires（SiCNWs）, SiO_2 nanoshells with a thickness of approximately 2 nm and Fe_3O_4 nanoparticles were grown on the surface of SiCNWs to form SiC@SiO_2@Fe_3O_4 hybrids. The microwave absorption performance of the SiC@SiO_2@Fe_3O_4 hybrids with different thicknesses was investigated in the frequency range from 2 to 18 GHz using a free-space antenna-based system. The results indicate that SiC@SiO_2@Fe_3O_4 hybrids exhibit improved microwave absorption. In particular, in the case of an SiC@SiO_2 to iron（III） acetylacetonate mass ratio of 1：3, the microwave absorption with an absorber of 2-mm thickness exhibited a minimum reflection loss of-39.58 d B at 12.24 GHz. With respect to the enhanced microwave absorption mechanism, the Fe_3O_4 nanoparticles coated on SiC@SiO_2 nanowires are proposed to balance the permeability and permittivity of the materials, contributing to the microwave attenuation.

关键词： silicon carbide nanowires hybrids microwave absorption mechanism impedance match

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Reaction behavior of trace oxygen during combustion of falling FeSi75 powder in a nitrogen flow

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 959-965页

作者： Bin Li jun-hong chen Peng Jiang Ming-wei Yan Jia-lin Sun Yong Li School of Materials Science and Engineering University of Science and Technology Beijing

To explore the reaction behavior of trace oxygen during the flash combustion process of falling FeSi75 powder in a nitrogen flow, a flash-combustion-synthesized Fe-Si;N;sample was heat-treated to remove SiO;. The samples before and after the treatment were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and the formation mechanism of SiO;was investigated. The results show that SiO;in the Fe-Si;N;is mainly located on the surface or around the Si;N;particles in dense areas, existing in both crystalline and amorphous states; when the FeSi75 particles, which are less than 0.074 mm in size, fell in up-flowing hot N;stream, trace oxygen in the N;stream did not significantly hinder the nitridation of FeSi75 particles as it was consumed by the surface oxidation of the generated Si;N;particles to form SiO;. At the reaction zone, the oxidation of Si;N;particles decreased the oxygen partial pressure in the N;stream and greatly reduced the opportunity for FeSi75 particles to be oxidized into SiO;; by virtue of the SiO;film developed on the surface, the Si;N;particles adhered to each other and formed dense areas in the material.

关键词： silicon nitride combustion synthesis oxygen atmosphere

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Losartan reduced connexin43 expression in left ventricular myocardium of spontaneously hypertensive rats

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第6期9卷 448-454页

作者： Li-li ZHAO hong-juan chen jun-zhu chen Min YU Yun-lan NI Wei-fang ZHANG Department of Cardiology the First Affiliated Hospital School of Medicine Zhejiang University Hangzhou 310003 China

Objective:To assess the effect of angiotensin II type 1(AT1)receptor antagonist losartan on myocardium con- nexin43(Cx43)gap junction(GJ)expression in spontaneously hypertensive rats(SHRs)and investigate possible mechanisms. Methods:Sixteen 9-week-old male SHRs and 8 age-matched male Wistar-Kyoto(WKY)rats were included in this *** were randomly divided into two groups to receive losartan at 30 mg/(kg·d)by oral gavage once daily for 8 weeks(SHR-L)or vehicle(0.9%saline)to act as controls(SHR-V);WKY rats receiving vehicle for 8 weeks served as normotensive *** the end of the experiment,rats were sacrificed and the hearts were *** of Cx43 and nuclear factor-kappaB p65 (NF-κB p65)proteins in all three groups were observed and further investigations on the effect of angiotensin II type 1 receptor antagonist losartan(30 mg/(kg·d),8 weeks)on Cx43 expression were conducted with Western blot and immunohistochemistry. NF-κB p65 protein in nuclear extracts was determined by Western ***:Left ventricular(LV)hypertrophy was prominent in SHRs,Cx43 and NF-κB p65 protein expressions were obviously upregulated and Cx43 distribution was dispersed over the cell *** with losarton reduced the over-expressions of Cx43 and NF-κB p65 in LV *** distribution of Cx43 gap junction also became much regular and confined to intercalated disk after losartan ***- sion:Cx43 level was upregulated in LV myocardium of SHR during early stage of *** II type 1 receptor antagonist losartan prevented Cx43 gap junction remodeling in hypertrophied left ventricles,possibly through the NF-κB pathway.

关键词： Connexin43 (Cx43) Left ventricular (LV) hypertrophy Angiotensin II Nuclear factor-kappaB p65 (NF-κB p65) Gap junction (GJ)

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T-2 toxin-induced apoptosis involving Fas,p53,Bcl-xL,Bcl-2,Bax and caspase-3 signaling pathways in human chondrocytes

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第6期9卷 455-463页

作者： Jing-hong chen jun-ling CAO Yong-lie CHU Zhi-lun WANG Zhan-tian YANG hong-lin WANG Ministry of Education Key Laboratory of Environment and Genes related to Diseases Institute of Endemic Diseases School of Medicine Xi ＇an Jiaotong University Xi ＇an 710061 China

Objective:To investigate the effects of T-2 toxin on expressions of Fas,p53,Bcl-xL,Bcl-2,Bax and caspase-3 on human ***:Human chondrocytes were treated with T-2 toxin(1～20 ng/ml)for 5 ***,p53 and other apoptosis-related proteins such as Bax,Bcl-2,Bcl-xL,caspase-3 were determined by Western blot analysis and their mRNA expressions were determined by reverse transcriptase-polymerase chain reaction(RT-PCR).Results:Increases in Fas,p53 and the pro-apoptotic factor Bax protein and mRNA expressions and a decrease of the anti-apoptotic factor Bcl-xL were observed in a dose-dependent manner after exposures to 1～20 ng/ml T-2 toxin,while the expression of the anti-apoptotic factor Bcl-2 was ***,T-2 toxin could also up-regulate the expressions of both pro-caspase-3 and caspase-3 in a dose-dependent ***:These data suggest a possible underlying molecular mechanism for T-2 toxin to induce the apoptosis sig- naling pathway in human chondrocytes by regulation of apoptosis-related proteins.

关键词： Apoptosis Apoptosis-related proteins Chondrocyte T-2 toxin

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Morphology characterization of periclase–hercynite refractories by reaction sintering

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International Journal of Minerals,Metallurgy and Materials 2015年第11期22卷 1219-1224页

作者： Peng Jiang jun-hong chen Ming-wei Yan Bin Li Jin-dong Su Xin-mei Hou School of Materials Science and Engineering University of Science and Technology Beijing Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing

A periclase？hercynite brick was prepared via reaction sintering at 1600℃for 6 h in air using magnesia and reaction-sintered hercynite as raw materials. The microstructure development of the periclase-hercynite brick during sintering was investigated using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. The results show that during sintering, Fe^2＋, Fe^3＋ and Al^3＋ ions in hercynite crystals migrate and react with periclase to form（Mg1-xFex）（Fe2-yAly）O4 spinel with a high Fe/Al ratio. Meanwhile, Mg^2＋ in periclase crystals migrates into hercynite crystals and occupies the oxygen tetrahedron vacancies. This Mg^2＋ migration leads to the formation of（Mg1-uFeu）（Fe2-vAlv）O4 spinel with a lower Fe/Al ratio and results in Al3＋ remaining in hercynite crystals. Cation diffusion between periclase and hercynite crystals promotes the sintering process and results in the formation of a microporous structure.

关键词： refractories periclase hercynite sintering morphology diffusion

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