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Improvement of elevated-temperature strength and recrystallization resistance via Mn-containing dispersoid strengthening in Al-Mg-Si 6082 alloys

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Journal of Materials Science & Technology 2020年第4期39卷 135-143页

作者： chen Li Kun Liu x.-Grant chen Department of Applied Science University of Québec at ChicoutimiChicoutimiQC G7H 2B1Canada

The precipitation behavior of Mn-containing dispersoids in Al-Mg-Si 6082 alloys with different Mn contents(0,0.5 and 1.0 wt%)during various heat treatments(300–500℃)was *** effects of dispersoids on elevated-temperature strength and recrystallization resistance during hot-rolling and post-rolling annealing were *** results showed that the dispersoids in the Mn-containing alloys(0.5 and 1.0%)began to precipitate at 350℃and reached the optimum conditions after 2–4 h at 400℃.However,the dispersoids coarsened with increasing holding time at temperatures above450℃.After the peak precipitation treatment at 400℃for 2 h,the yield strength at 300℃increased from 28 MPa(base alloy free of Mn)to 55 MPa(alloy with 0.5%Mn)and 70 MPa(alloy with 1%Mn),respectively,demonstrating a significant dispersoid strengthening effect at elevated *** addition,the dispersoids were thermally stable at 300℃for up to 1000 h holding owing to its relative high precipitation temperature(350–400℃),leading to the superior constant mechanical performance at elevated temperature during the long service *** hot rolling and post-rolling annealing,the presence of a large amount of dispersoids results in the higher Zener drag PZcompared with base alloy and then significantly improved the recrystallization *** alloy containing 0.5%Mn ex.ibited the highest recrystallization resistance among three ex.erimental alloys studied during the post-rolling process,likely resulted from the lower coarsening rate of dispersoids and the lower dispersoids free zone.

关键词： Al-Mg-Si 6082 alloy Mn addition Dispersoid precipitation Elevated-temperature strength Recrystallization resistance

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Effects of Mn content on recrystallization resistance of AA6082 aluminum alloys during post-deformation annealing

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Journal of Materials Science & Technology 2020年第17期52卷 189-197页

作者： x.aoming Qian Nick Parson x.-Grant chen Department of Applied Science University of Quebec at ChicoutimiSaguenay G7H 2B1Canada Arvida Research and Development Centre Rio Tinto AluminumSaguenay G7S 4K8Canada

The microstructural evolutions under as-homogenized and as-deformed conditions and after the postdeformation annealing of AA6082 aluminum alloys with different Mn content(0.05 wt.%-1 wt.%)were studied by optical,scanning electron,and transmission electron *** results showed that the presence of a large amount ofα-Al(Mn,Fe)Si dispersoids induced by Mn addition significantly improved the recrystallization *** the base alloy free of Mn,static recrystallization occurred after 2 h of annealing,and grain growth commenced after 4 h of annealing,whereas in Mn-containing alloys,the recovered grain structure was well-retained after even 8 h of *** alloy with 0.5%Mn ex.ibited the best recrystallization resistance,and a further increase of the Mn levels to 1%resulted in a gradual reduction of the recrystallization resistance,the reason for which was that recrystallization occurred only in the dispersoid-free zones(DFZs)and the increased DFZ fraction with Mn content led to an increase in the recrystallization *** variation in the dispersoid number density and a coarsening of dispersoids during annealing have a limited influence on the static recrystallization in Mn-containing alloys.

关键词： AA6082 alloys Mn effects Recrystallization resistance Dispersoid precipitation Post-deformation annealing

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Electronic and magnetic structures of chain structured ironselenide compounds

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Frontiers of physics 2014年第4期9卷 465-471页

作者： Wei Li Chandan Setty x. H. chen Jiangping Hu State Key Laboratory of Functional Materials for Informatics and Shanghai Center for Superconductivity Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China Department of Physics and State Key Laboratory of Surface Physics Fudan University Shanghai 200433 China Department of Physics Purdue University West Lafayette IA 47907 USA Hefei National Laboratory for Physical Science at Microscale and Department of Physics University of Science and Technology of China Hefei 230026 China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China

Electronic and magnetic structures of iron selenide compounds Ce2O2FeSe2 （2212＊） and BaFe2Se3 （123＊） are studied by the first-principles calculations. We find that while all these compounds are composed of one-dimensional （1D） Fe chain （or ladder） structures, their electronic structures are not close to be quasi-lD. The magnetic ex.hange couplings between two nearest-neighbor （NN） chains in 2212＊ and between two NN two-leg-ladders in 123＊ are both antiferromagnetic （AFM）, which is consistent with the presence of significant third NN AFM coupling, a common feature shared in other iron-chalcogenides, FeTe （11＊） and KyFe2-x.e2 （122＊）. In magnetic ground states, each Fe chain of 2212＊ is ferromagnetic and each two-leg ladder of 123＊ form a block-AFM structure. We suggest that all magnetic structures in iron-selenide compounds can be unified into an ex.ended J1-J2-J3 model. Spin-wave ex.itations of the model are calculated and can be tested by future ex.eriments on these two systems.

关键词： first-principles calculations magnetism spin-wave ex.itations

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EFFECTS OF ZIRCONIUM ON MICROSTRUCTURES AND MECHANICAL PROPERTIES OF MICROALLOYED STEELS

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 319-327页

作者： T．H．x. x. chen P.H. Li Z.x. Yuan Technology Center of Wuhan Iron ＆ Steel （Group） Corp. Wuhan 430080 China School of Materials and Metallurgy Wuhan University of Science and TechnologyWuhan 430081 China

The effects of Zr on the microstructures and mechanical properties of microalloyed steels have been investigated by mechanical tests and microstructural observations. The microstructures in the Zr-doped steels are ferrite plus pearlite, which is similar to those in the Zr-free steel. With the increase in the Zr content, the lamellar structure reduces and even disappears. Sulfides and silicates that ex.st in the Zr-free steel are modified into fine ox.des in the Zr-bearing steel. When the Zr contents range from 0.01wt% to 0.03wt%, the low temperature toughness of the steel can be substantially improved while its room-temperature strength and ductility have no apparent change. The refinement of ferrite grain size by the addition of zirconium is one of the main reasons for this toughness improvement.

关键词： zirconium microalloyed steel microstructure mechanical property

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CREVICE CORROSION BEHAVIOR OF x.0 STEEL IN HCO_3^- SOLUTION UNDER CATHODIC POLARIZATION

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Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 235-244页

作者： C.W. Du x.G. Li x. chen P. Liang H. Guo School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Liaoning University of Petroleum and Chemical Technology ~shun 113001 China

The crevice corrosion behavior of x.O steel was investigated with a wedge-shaped crevice assembly under -1000 m V （SCE） cathodic polarization in the solutions with various HCO3 concentrations. The potential, current, pH and the ox.gen content within the crevice were measured with or without outside coupled specimen. The results indicated that the polarization potential of x.O steel in the crevice dropped with the increase of time under the cathodic polarization. There was a remarkable influence of HCO3 concentration on the potential of x.O steel in the crevice. When HCO3 concentration was up to 0.125%, the surface of the metal was covered with the corrosion products that resulted in the polarization ex.ent of x.O steel decreased. The pH value in the crevice rose and it dropped gradually from the crevice mouth to the bottom under the cathodic polarization. With the increasing of HCO3 concentration, the hydrolyzation reaction of metal in the crevice bottom aggravated. Most of the dissolved ox.gen in the crevice was consumed by the cathodic current. The max.mum cathodic current on the metal surface was at the crevice mouth and it was much more than that at the crevice bottom.

关键词： Cathodic polarization x.O steel Potential pH value Ox.gen

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ANALYSIS OF THREE-DIMENSIONAL UPSETTING PROCESS BY THE RIGID-PLASTIC REPRODUCING KERNEL PARTICLE METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 371-378页

作者： Y. H. Liu J. chen S. Yu x. W. chen National Die and Mould CAD Engineering Research Center Shanghai Jiao Tong UniversityShanghai 200030 China

A meshless approach, called the rigid-plastic reproducing kernel particle method （RKPM）, is presented for three-dimensional （3D） bulk metal forming simulation. The approach is a combination of RKPM with the flow theory of 3D rigid-plastic mechanics. For the treatments of essential boundary conditions and incompressibility constraint, the boundary singular kernel method and the modified penalty method are utilized, respectively. The arc-tangential friction model is employed to treat the contact conditions. The compression of rectangular blocks, a typical 3D upsetting operation, is analyzed for different friction conditions and the numerical results are compared with those obtained using commercial rigid-plastic FEM （finite element method） software Deform^3D. As results show, when handling 3D plastic deformations, the proposed approach eliminates the need of ex.ensive meshing and remeshing procedures which are unavoidable in conventional FEM and can provide results that are in good agreement with finite element predictions.

关键词： meshless reproducing kernel particle method(RKPM) three-dimensional upsetting incompressibility modified penalty method

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Flux.measurements for a DD neutron generator using neutron activation analysis

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Nuclear Science and Techniques 2018年第4期29卷 66-71页

作者： Walid A. Metwally Samar El-Sayed Ahmad Ababneh David L. Williams Allan x. chen Department of Nuclear Engineering University of SharjahSharjah 27272 UAE Adelphi Technology 2003 E Bayshore Rd. Redwood CityCA 94063 USA

The fast and max.mum thermal neutron flux.s from the DD-109 neutron generator at the University of Sharjah were ex.erimentally measured by the activation technique using different neutron reactions. The thermal and fast neutron flux.s were found to be 2.960 × 10~6 and6.186 × 10~7 n/cm^2 s, respectively. This was done to verify the modeling results for the optimum moderator thickness needed to max.mize the thermal neutron flux. The optimum moderator thickness was found to be between 3.5 and4 cm. The present data were compared with the detailed MCNP model-based calculation performed in earlier work to simulate the generator.

关键词： Neutron activation analysis Neutron generator Neutron moderation Thermal neutron flux measurement

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IGF-1R as an anti-cancer target—trials and tribulations

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Chinese Journal of Cancer 2013年第5期32卷 242-252页

作者： Helen x. chen Elad Sharon Cancer Therapy Evaluation Program National Cancer Institute

Type I insulin-like growth factor receptor (IGF-1R) has long been recognized for its role in tumorigenesis and growth, but only recently have the tools for targeting the IGF pathway become available. More than 10 IGF/IGF-1R inhibitors have entered clinical trials, and these belong to three main classes: (1) monoclonal antibodies against IGF-1R, (2) monoclonal antibodies against IGF-1R ligands (IGF-1 and IGF- 2), and (3) IGF-1R tyrosine kinase inhibitors. These IGF-1R-targeting agents share common effects on IGF-1R signaling but differ in mechanisms of action, spectrum of target inhibition, and pharmacological features. Clinical activity of IGF-1R inhibitors has been demonstrated with sustained responses in a small number of patients with select tumor types, such as Ewing sarcoma and thymoma. However, many large clinical trials involving patients with adult tumors, including non-small cell lung cancer, breast cancer, and pancreatic cancer, failed to show clinical benefit in the overall patient population. Possible reasons for failure include the complex.ty of the IGF-1R/insulin receptor system and parallel growth and survival pathways, as well as a lack of patient selection markers. While IGF-1R remains a valid target for selected tumor types, identification of predictive markers and rational combinations will be critical to success in future development.

关键词： IGF-1 酪氨酸激酶抑制剂胰岛素样生长因子生长因子受体单克隆抗体肿瘤发生临床试验抗癌

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An Improvement on the Efficiency of a Single Rotor Transonic Compressor by Reducing the Shock Wave Strength on the Blade Suction Surfaces

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Journal of Thermal Science 2012年第2期21卷 127-135页

作者： S. J. Geng N. x. chen H. W. Zhang W. G. Huang Institute of Engineering Thermophysics Chinese Academy of Sciences EO. Box 2706 Beijing 100190 China

It is well known that increasing the rotational velocity is an effective way to increase the total pressure ratio. With increasing flow velocity especially under the condition of transonic flow in the supersonic region, where ex.st strong shock waves, the shock wave loss becomes main and important. Simultaneously, there occurs boundary layer separation due to the shock wave / boundary layer interaction. In the present paper the transonic compressor blades were studied and analyzed to find a proper and simple way to reduce the shock wave loss by optimizing the suction surface configuration or controlling the gradient of isentropic Mach number on the suction surface. A Navier-Stokes solver combined with a modified design algorithm was developed and used. The NASA single rotor for transonic flow compressor was served as a numerical ex.mple to show the effectiveness of this method. Two cases for both original and modified rotors were analyzed and compared.

关键词： Transonic compressor shock wave loss efficiency improvement blade optimization

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Straight-Leaned Blade Aerodynamics of A Turbine Nozzle Blade Row with Low Span-Diameter Ratio

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Journal of Thermal Science 2000年第1期9卷 51-52页

作者： N. x. chen Y. J. x. W.G Huang Institute of Engineering Thermophysics Chinese Academy of Sciences P.O. Box 2706 Beijing 100080

Compound-leaned blades have been applied for the design of turbomachinery for reducing secondary flow losses and then improving the aerodynamic performance. The aerodynamics features are not clear enough so far and, therefore, have been investigted by many authors ex.erimentally and numerically. The present study on turbomachinery aerodynamics is emphasized on the leaning effects of straight-leaned turbine nozzle blades With low span-diameter ratio (less than 0.1). This Kind of blades has relatively low efficiency. This is due to that the blades are too short and then the loss contours of both tip and hub surfaces are merged with each other. How to increase the efficiency efficiency becomes of the important subjects, which is faced to the turbomachinery community. Effects of straight-leaned blades in a turbine nozzle blade row with low span-diameter ratio have been assessed using three-dimensional steady Reynolds-averaged Navier-Stokes computations.

关键词：透平机导向器叶片空气动力学

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