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Sample selection for models to represent ceramic cores fabricated by stereolithography three-dimensional printing

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j.urnal of Materials Science & Technology 2022年第26期121卷 117-123页

作者： X.l.An j.j.liang j.G.li j.W.Chen Y.z.zhou X.F.Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Space Manufacturing Technology(CAS Key lab) Beijing 100094China

Ceramic cores with good chemical stability and moderate mechanical properties near casting temperatures of 1550℃ for example are used for the manufacturing of internal structures of hollow blades,requiring complex structures and high precision[1–3].However,traditional preparation method based on investment casting is tedious,requiring not only long production cycles but also high cost[4].

关键词： investment printing ceramic

Polysorb^R(an absorbable lactomer) staples, a safe closure technique for distal pancreatic resection

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World j.urnal of Gastroenterology 2014年第45期20卷 17185-17189页

作者： Gyula Farkas lászló leindler j.nos Márton Gyorgy l.zár Gyula Farkas Department of Surgery Faculty of Medicine University of Szeged H-6701 SzegedHungary

AIM:To investigate twenty-year experience evaluated the use of the PolysorbR(an absorbable lactomer)staples for distal pancreatic ***:The data on 150 patients[92 men,58women,mean age 52(24-72)years]who underwent distal pancreatectomy(DP)in the last 20 years were collected prospectively from an electronic *** diagnosis was confirmed by endoscopic retrograde cholangiopancreatography,sonography,computed tomography and/or magnetic resonance *** indications for DP were focal pancreatic necrosis,spontaneous pancreatic fistulas,abscesses,pseudocysts,segmental chronic obstructive pancreatitis in the tail,traumatic disruption,and benign(cystadenomas,insulinomas,or glucagonomas)or malignant *** distal resections were performed without splenectomy in 29 of the 150 patients(19%).In the event of splenectomy,the splenic artery and vein were individually ligated,the TA-55 Auto Suture stapler,loaded with Premium PolysorbR 55 staples(5.5mm),was placed across the gland,and the trigger was pulled,the action of which produced two staggered absorbable suture *** gland distal to the stapler wasthen amputated with a scalpel on the TA-55 stapler and the two rows of staples were left in the proximal pancreatic *** the distal resection,a drainage tube was inserted into the pancreatic ***:The average duration of the operation was150 min(range:90-210 min)and no transfusion was indicated during the *** DP in one patient a type B fistula was diagnosed,which was treated successfully by conservative treatment comprising of 12-d octreotide medication(3×0.1 mg/d)and j.j.nal *** incidence of postoperative pancreatic fistula was therefore0.6%.Another 2 patients suffered postoperative pancreatitis,which was also conservatively *** were performed in 2 patients on the first or second postoperative day,necessitated by bleeding from the retroperitoneal *** morbidity was 3.3%(5 patients),but no mortality

关键词： Distal pancreatic resection PolysorbR sta-ples Closure technique long-term experience Pancre-atic fistula

Precipitation of multi-type nano-quasicrystals in a Mg-zn-Y alloy

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j.urnal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： W.z.Wang X.z.zhou l.F.zhang H.Q.Ye z.Q.Yang Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China j. Hua laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex laves Mg-zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

Ultrasonic-based surface patterning and interfacial reaction of zrO_(2)ceramics

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j.urnal of Materials Science & Technology 2023年第24期155卷 202-210页

作者： H.j. Dong z.l. li X.G.Song j.C. Feng S.j. Wei j.H. Fu Y. Shi State Key laboratory of Advanced Welding and j.ining Harbin Institute of Technology Harbin 150001 China Shandong Provincial Key lab of Special Welding Technology Harbin Institute of Technology at Weihai Weihai 264209 China

We demonstrate a process to achieve selective surface metall.zation of zrO_(2)ceramics using ultrasound technology in atmospheric environments at 350℃,which bestows good weldability of zrO_(2)to achieve rapid and reliable connections with other metals as well as ceramic *** challenge is that brazing or diffusion welding processes to accomplish metallurgical connections for zrO_(2) typically require holding at elevated temperatures for minutes to hours,while the selective ultrasonic metall.zation process requires only a few seconds of processing without the application of covering films or solder *** this study,the selected Sn-2Ti alloy could effectively wet and spread on zrO_(2)substrate under ultrasonication,and continuous interphase layers were rapidly formed in situ between zrO_(2)and *** bonding strength for the zrO_(2)/Sn-2Ti interface was well established with the highest shear strength of 37.1 MPa,and the fracture location occurred at the filler *** interfacial reaction layer thickened remarkably with the prolongation of sonication,accompanied by the partial crystall.zation of amorphous TiO and the formation of irregularly striped Ti_(11.31)Sn_(3)O_(10)nanocrystals.

关键词： Selective ultrasonic metall.zation zirconia surface patterning low temperature connection Sono-oxidation Interfacial reaction

Coarsening Behavior of Gamma Prime Precipitates in a Nickel Based Single Crystal Superalloy

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j.urnal of Materials Science & Technology 2016年第2期32卷 172-176页

作者： S.Tang l.K.Ning T.z.Xin z.zheng University of Chinese Academy of Sciences.Beij.ng 100049.China Superalloy Division.Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The γ/γ＇ microstructural evolution in a nickel based single crystal superalloy during load-free thermal exposure at 900 ℃ has been further investigated in this paper. The growth characteristics of γ＇ precipitates were discussed in detail. The generation of interfacial dislocations would accelerate the rate of coalescence in the dendrite arms. The average sizes of precipitates were used to compare interface with diffusion controlled growth mechanism and no mechanism seems obviously dominant, although the square rate law gives slightly better fit. The coarsening behavior may be controlled by diffusion through the ragged interface between the γ＇ precipitate and the y matrix.

关键词： Single crystal superalloy Coarsening Interfacial dislocations Rate controlling mechanism

Constitutive equation and model validation for a 31 vol.% B_4Cp/6061Al composite during hot compression

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j.urnal of Materials Science & Technology 2018年第10期34卷 1730-1738页

作者： l. zhou C. Cui Q.z. Wang C. li B.l. Xiao z.Y. Ma Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Electromechanical and Vehicle Engineering Yantai University Yantai 264005 China School of Mechanical Engineering Shenyang Ligong University Shenyang 110159 China Nuclear and Radiation Safety Center Ministry of Environmental Protection Beijing 100082 China

An accurate constitutive equation is essential to understanding the flow behavior of B4C/A1 compos-ites during the hot deformation. However, the constitutive equations developed previously in literature are generally for low strain rate deformation. In the present work, we modified the general consti-tutive equation and take the high strain rate correction into account. The constitutive equation for a 31 vol.% B4Cp/6061AI composite was constructed based on the flow stresses measured during isothermal hot compression at temperatures ranging from 375 to 525 ℃ and strain rates from 0.01 to 10 s^-1. The experimental flow stresses were corrected by considering temperature-dependent Arrhenius factor. The modified equation was then verified by using DEFORM-3D finite element analysis to simulate the exper-imental hot compression process. The results show that the modified equation successfully predicts flow stress, load-displacement, and the temperature rise. This helps to optimize the hot deformation process, and to obtain desirable properties, such as reduced porosity and homogenous particle distribution in B4C/AI composites.

关键词： Composites B4C/AI Constitutive equation Hot compression Finite element simulation

DIFFERENTIAl SCANNING CAlORIMETRY AND X-RAY DIFFRACTION STUDIES ON AGING BEHAVIOR OF zn-Al AllOYS

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Acta Metallurgica Sinica(English letters) 2001年第2期14卷 109-114页

作者： X.l. Xu, z. W. Yu, S.j. j., j.C. Sun and z.K. Hei (Dalian Maritime University, Dalian 116024, China) Dalian Maritime Univ. Dalian 116024 China

Decomposition processes of the quenched zn-Al alloys were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the stabilities of supersaturated solid solution (SSS) of zn-Al alloy and α' phase formed by quenching would reduce with the increase of zn content and the precipitation of η-zn phases even when aging at ambient temperature, so that the exothermic precipitation peak in DSC curve would disappear. The activation energy of the η-zn precipitation and the reaction enthalpy were calculated and measured. The kinetics of α' decomposition or η-zn formation was determined by XRD. The microstructure change during aging was observed by TEM.

关键词： Aging of materials Aluminum alloys Differential scanning calorimetry X ray diffraction

STRUCTURAl DETERMINATION OF TITANIUM-OXIDE NANOPARTIClES BY X-RAY ABSORPTION SPECTROSCOPY

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Acta Metallurgica Sinica(English letters) 2002年第1期15卷 53-57页

作者： z.Y. Wu j. zhang K. Ibrahim M.I. Abbas G. li Y. Tao T.D. Hu F.Q. liu H.j. Qian Y.N. Xie Q.H. zhang l. Gao z.z. Chen Beij.ng Synchrotron Radiat. Facility Inst. of High Energy Phys. Chinese Acad. of Sci. Beijing 100039 China

As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.

关键词： X-ray absorption near edge structure nano particle transition metal oxide

Consolidation of AA 7075-2 wt% zrO2 Composite Powders by Severe Plastic Deformation via ECAP

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Acta Metallurgica Sinica(English letters) 2016年第10期29卷 895-901页

作者： S. E. Hernandez-Martinez j. j. Cruz-Rivera R. Martinez-Sanchez C. G. Garay-Reyes j. A. Mufioz-Bolanos j. M. Cabrera j.l.Hernández-Rivera Instituto de Metalurgia Universidad Autonoma de San Luis Potosi Sierra Leona 550 78210 San Luis Potosi Mexico Centro de Investigacion en Materiales Avanzados (CIMAV) Miguel de Cervantes 120 31109 Chihuahua Mexico Departamento de Ciencia de Materiales e Ingenieria Metalurgica Universitat Politecnica de Catalunya Av Diagonal 647 08028 Barcelona Spain Fundacion CTM Centro Tecnologico Plaza de la Ciencia 208243 Manresa Spain CONACYT Research Fellow-Instituto de Metalurgia Universidad Autonoma de San Luis Potosi- Sierra Leona 550 78210 San Luis Potosf Mexico

The powders of the AA 7075-zRO2 were mixed by mechanical milling, but it was found that the system presents a few disadvantages when processed by conventional sintering and hot extrusion, since intermetallic phases between zrO2 particles and alloying elements were formed. Equal channel angular pressing （ECAP） processing was proposed as an alternative method to consolidate the composite where there is no intermetallic formation. The analysis of the ECAP process showed that the intermediate temperature （220℃） produced a higher consolidation level than conventional sintering and hot extrusion （400 and 500℃, respectively）. This fact was supported by relative density analysis. In the case of the sintered and hot-extruded sample, the relative density exhibited a value of 0.95, while ECAP sample showed a value of 0.98. Hardness values show that microstructural refinement obtained during mechanical milling was preserved during ECAP processing even when it was carded out at 220℃.

关键词： Metal matrix composites (MMCs) Powder consolidation Severe plastic deformation (SPD)