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Crystal structure,phase transitions,and thermodynamic properties of magnesium metavanadate(MgV_(2)O_(6))

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Journal of Magnesium and alloys 2024年第4期12卷 1449-1460页

作者： Guishang Pei Cheng Pan Dapeng Zhong Junyi Xiang Xuewei Lv College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Key Laboratory of Vanadium-titanium Metallurgy and Advanced Materials Chongqing UniversityChongqing 400044China Pangang Group Research Institute Co. Ltd.Panzhihua 617000China

As a promising anode material for magnesium ion rechargeable batteries,magnesium metavanadate(MgV_(2)O_(6))has attracted considerable research interest in recent years.A MgV_(2)O_(6)sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V2O5 powder under an air *** solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)occurred at 841 K and the enthalpy change was 4.37±0.04 kJ/*** endothermic effect at 1014 K and the enthalpy change was 26.54±0.26 kJ/mol,which is related to the incongruent melting ofβ-MgV_(2)O_(6).In situ XRD was performed to investigate phase transition of the as-prepared MgV_(2)O_(6)at high *** cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group,and the lattice parameters of a=9.280 A°,b=3.501 A°,c=6.731 A°,β=111.76°.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)was further studied by thermal kinetics,indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating ***,the enthalpy change of MgV_(2)O_(6)at high temperatures was measured utilizing the drop calorimetry,heat capacity was calculated and given as:Cp=208.3+0.03583T-4809000T^(−2)(298-923 K)(J mol^(−1)K^(−1)),the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV_(2)O_(6)at high temperatures.

关键词： MgV_(2)O_(6) Crystal structure Phase transitions Thermodynamic functions

Influence of Micro/Nano-Ti Particles on the Corrosion Behavior of AZ31-Ti Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 484-498页

作者： Jinchao Jiao Jin Zhang Yong Lian Shengli Han Kaihong Zheng Fusheng Pan Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 10083China Beijing Key Laboratory for Corrosion Erosion and Surface Technology Beijing 100083China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China National Engineering Research Center for Magnesium alloys Chongqing UniversityChongqing 404100China

Adding Ti particles to magnesium alloy simultaneously enhances its strength and ***,how these particles influence on Mg alloy’s corrosion performance is seldom *** corrosion behavior of AZ31-Ti composites containing titanium nanoparticles(1.5 and 5 wt%)and micron particles(10 wt%)prepared by powder metallurgical in 3.5 wt%NaCl solution was *** results indicate that Ti particles serve as the primary location for the cathodic hydrogen reduction reaction,resulting in intense galvanic corrosion between the Ti and Mg *** nanoparticles distributed at the interface of the original AZ31 powder were in a discontinuous mesh structure,thus failing to act as a barrier against *** corrosion products with the existence of numerous cracks gradually peel off during the corrosion process and cannot protect the *** average corrosion rate P_(w) of AZ31,AZ31-1.5%Ti,AZ31-5%Ti,and AZ31-10%Ti after 7 days of immersion is 27.55,105.65,283.67,and 99.35 mm/y,***,AZ31-Ti composites can be considered as potential candidates for degradable fracturing ***,it is recommended to improve their corrosion resistance through surface treatment.

关键词： AZ31-Ti composite Nano-Ti Micro-Ti Corrosion behavior Scanning Kelvin probe force microscopy(SKPFM)

Modeling asymmetric fracture mechanics of Mg alloy wire in drawing process

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Journal of Magnesium and alloys 2024年第5期12卷 2057-2069页

作者： Sunghoon Choi Jongwon Shin Joung Sik Suh Dongchoul Kim Department of Mechanical Engineering Sogang UniversitySeoul04107Republic of Korea Advanced Metals division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

In this study,a numerical analysis was conducted on the ductile fracture of a 2-mm diameter Mg-1Zn-0.5Mn-0.5Sr-0.1Ca alloy wire during *** hexagonally close-packed crystal structure of Mg alloys causes asymmetric fracture behavior,especially in the compression *** aim of this study is to develop a comprehensive damage model for Mg alloy wire that accurately predicts ductile fracture,with a focus on the compression region.A novel experimental method was introduced to measure the ductile fracture of Mg alloy wires under different stress *** wire drawing process was simulated using the Generalized Incremental Stress-State dependent damage(GISSMO)Model and the Semi-Analytical Model for Polymers(SAMP)*** damage model's prediction and the experimental results were found to be in excellent agreement,especially in determining crack *** analysis established a safe zone diagram for die angle and reduction ratio,and experimental validation confirmed the feasibility of this *** proposed damage model can provide a practical and reliable analysis for optimizing the drawing process of Mg alloy wire.

关键词： Mg alloy Wire drawing Finite element method Damage model Safe zone diagram

Superelastic metastable Ti-Mo-Sn alloys with high elastic admissible strain for potential bio-implant applications

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Journal of Materials Science & Technology 2023年第32期163卷 45-58页

作者： Shuanglei Li Jae H.Kim Seung Won Kang Jae Ho Kim Tae-Hyun Nam Jong-Taek Yeom titanium alloys Department Metal Materials DivisionKorea Institute of Materials Science(KIMS)Changwon 51508Republic of Korea Department of Materials Engineering and Convergence Technology&Research Institute for Green Energy Convergence Technology(RIGET) Gyeongsang National University900 GazwadongJinjuGyeongnam 52828Republic of Korea

The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is ***-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional *** this study,a wide content range of(0-15)wt%of low-cost,toxicity-free,and high-biocompatible Sn element was added to the Ti-8Mo(wt%)alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn *** tailoring Sn content,desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn *** was found that the increase in Sn content stabilized theβphase and a singleβphase was obtained at room temperature in Ti-8Mo-(13,15)Sn *** addition of Sn modified the lattice parameters of theα″martensite andβphase and affected the lattice deformation stain ofβ→α″.The lattice deformation strain along the[011]βdirection was found to be decreased by-0.26%/wt%*** room temperature superelasticity with a recovery strain of 3.1%and an elastic admissible strain of 1%was obtained in the Ti-8Mo-13Sn *** Sn content increased to 15 wt%,a high elastic admissible strain of 1.56%and a recovery strain of 2.0%were *** Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications.

关键词： Ti-Mo-Sn alloy Shape memory alloy Elastic admissible strain Elastic modulus Superelasticity

Hierarchical structure and deformation behavior of a novel multicomponent β titanium alloy with ultrahigh strength

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Journal of Materials Science & Technology 2022年第12期107卷 227-242页

作者： X.Li X.N.Wang K.Liu G.H.Cao M.B.Li Z.S.Zhu S.J.Wu School of Materials Science and Engineering Beihang UniversityBeijing 100191China titanium alloys Laboratory Beijing Institute of Aeronautical MaterialBeijing 100095China School of Materials Science and Engineering Shanghai UniversityShanghai 200444China

Based on the general [Mo] equivalent criterion and d-electron orbital theory, a new ultrahigh-strength βtitanium alloy with eight major elements(Ti-4.5Al-6.5Mo-2Cr-2.6Nb-2Zr-2Sn-1V, TB17) for industrial applications was developed. An ingot of five tons was successfully melted by thrice vacuum consumable arc melting. The microstructure and elements partitioning of different conditions were investigated systematically. The results suggest that the hierarchical structures of micro-scale first α phase(αf), nano-scale secondary α phase(αs), and ultrafine FCC substructures can be tailored by solution plus aging(STA) heat treatment. The lateral and epitaxial growth of αfphase promotes the HCP-α to FCC substructure transformation with the help of elements partitioning during the aging process. Moreover, the element V, generally regarded as β stabilizer, is found to mainly concentrate in the Al-rich αfphase in this study probably due to its relatively lower content and the strong bonding energy of Al-V. The hierarchical structure has a strong interaction with dislocations, which contributes to achieve a superhigh strength of 1376 *** addition, the plastic strain is partitioned in the multi-scale precipitates(such as the α and FCC substructures) and β matrix, resulting in a considerable plasticity. TEM observation demonstrates that high density entangled dislocations at interfaces and mechanical twins exist in the STA sample after tensile test. It can be deduced that both dislocation slipping and twinning mechanisms are present in this ***, TB17 alloy can serve as an excellent candidate for structural materials on aircrafts that require high strength and lightweight.

关键词： titanium alloy Hierarchical structure Deformation behavior Ultrahigh strength Elements partitioning

Clinical diagnostic advances in intestinal anastomotic techniques:Hand suturing,stapling,and compression devices

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World Journal of Gastrointestinal Surgery 2024年第5期16卷 1231-1234页

作者： Ah Young Lee Joo Young Cho division of Gastroenterology Department of Internal MedicineCha Gangnam Medical CenterCha University College of MedicineSeoul 06135South Korea

The development of intestinal anastomosis techniques,including hand suturing,stapling,and compression anastomoses,has been a significant advancement in surgical *** methods aim to prevent leakage and minimize tissue fibrosis,which can lead to stricture *** healing process involves various phases:hemostasis and inflammation,proliferation,and *** staplers and sutures can cause inflammation and fibrosis due to the release of profibrotic *** anastomosis devices,including those made of nickel-titanium alloy,offer a minimally invasive option for various surgical challenges and have shown safety and ***,despite advancements,anastomotic techniques are evaluated based on leakage risk,with complications being a primary *** devices like Magnamosis use magnetic rings for compression anastomosis,demonstrating greater strength and patency compared to *** technology is also being explored for other medical *** there are promising results,particularly in animal models,the realworld application in humans is limited,and further research is needed to assess their safety and practicality.

关键词： Anastomoses Diagnostic advances,Anastomotic techniques Technique Intestine

Burning products of TA15 titanium alloy by friction oxygen concentration method

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Rare Metals 2018年第11期37卷 952-960页

作者： Nan Sui Guang-Bao Mi Meng-Qi Yan Jing-Xia Cao Xu Huang Aviation Key Laboratory of Science and Technology on Advanced titanium alloys AECC Beijing Institute of Aeronautical Materials

The microstructural characteristics, elemental distribution law and microscopic formation mechanism of the burning products of TA15 titanium alloy were investigated by friction oxygen concentration method, associated with in situ observation, X-ray diffraction(XRD),scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS) analyses, providing the thoughts to improve fireproof property. The results show that, when the friction contact pressure(p) is 0.20 MPa and oxygen concentration of premixed air flow(c) is 60 vol%, TA15 titanium alloy produces violent sparks and presents dazzling white light during combustion. The generated products after burning are mainly TiOand small amount of AlOoxides. Four distinct zones form from the combustion surface to the alloy matrix, and they are in the sequence of combustion zone, fusion zone, heat-affected zone and transition zone. Further, combustion zone is composed of TiOand A1203 compounds, containing obvious cracks. In the fusion zone, discontinuous oxygenrich Al-based solid solution forms, and the elemental distribution has strong volatility. In the heat-affected zone,there are abundant of Ti-based solid solution and small amount of Al-and Mo-based solid solution. Transition zone is made of lamellar structure. Two technical approaches are given to prevent oxygen diffusion inside the reaction zone and reaction-affected zone. On the one hand,the content of Al is designed as the upper limit of alloy composition; on the other hand, fireproof coatings are deposited on the surface of the alloy.

关键词： Friction oxygen concentration method TA15 titanium alloy Burning products Microstructure titanium fire

Size-controlled synthesis and red up-converted luminescence of CeO_(2):Yb^(3+)/Er^(3+) nanospheres

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Journal of Rare Earths 2023年第10期41卷 1487-1493,I0001页

作者： Xiaoqi Zhao Yami Ling Hao Suo Zhiyu Zhang Jiangrui Bai Chongfeng Guo College of Physics and Optoelectronic Technology&Advanced titanium alloys and Functional Coatings Cooperative Innovation Center Baoji University of Arts and SciencesBaoji721016China State Key Laboratory of Photon-Technology in Western China Energy Institute of Photonics&Photon-TechnologyNorthwest UniversityXi'an710127China

In this work,cubic-phased CeO_(2):18 mol%Yb^(3+)/2 moI%Er^(3+)nanospheres were prepared by coprecipitation method,in which the size of nanosphere was precisely controlled by regulating the amount of coprecipitator *** morphology evolution of CeO_(2):18%Yb3+/2%Er^(3+)samples that vary from nanosphere to nano-flower with extending the reaction time was elaborately investigated via increasing the amount of urea and increasing the reaction *** influence of non-radiative relaxation(NR)processes and surface quenching on up-conversion emission output of CeO_(2):18%Yb^(3+)/2%Er^(3+)was investigated through varying the sizes and environmental *** imaging experiment demonstrates that CeO_(2):18%Yb^(3+)/2%Er^(3+)nanospheres have the potential to act as luminescent imaging reagents in tissue imaging.

关键词： Up-conversion Non-radiative relaxation Morphology evolution Tissue imaging Rare earths

Effect of size and distribution of titanium carbide on microstructure and mechanical properties of Ti-25V-15Cr-2Al-0.2C-0.2Si alloy

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中国有色金属学会会刊：英文版 2005年第4期15卷 722-726页

作者：雷力明黄旭王宝赵红霞曹春晓 D.Rugg W.Voice Laboratory of titanium alloys Beijing Institute of Aeronautical Materials Rolls-Royce Plc P.O.Box 31

The effect of size and distribution of titanium carbide on the microstructure and mechanical properties of non-burning β titanium alloy Ti-25V-15Cr-2Al-0.2C-0.2Si (mass fraction, %) was investigated. The microstructure of the heat-treated and exposed alloy was studied using optical microscopy(OM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). It is found that carbides with finer size and more uniform distribution can suppress the formation of α precipitates more effectively, and can especially decrease the amount of grain boundary α precipitates after long-term exposure at 540℃ (the expected application temperature). Thus, significant improvement in thermal stability can be achieved by refining carbide particles in the matrix of the alloy.

关键词：二氧化钛微结构合金热处理