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On the mechanism of Si-promoted destabilization of TiC_(x)particles in Al alloys

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journal of Materials Science & Technology 2023年第34期165卷 17-26页

作者： H.Dong y.C.Guo y.Z.Chen F.Xia Q.Q.Guo Q.Chen G.L.Li j.y.zhao y.Zhong j.P.Li School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an 710021China State Key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China School of Science Xi’an University of Science and TechnologyXi’an 710054China

TiC_(x)is an excellent composite strengthening particle and grain refiner for Al ***,the stability of TiC_(x)is poor when solute Si exists in Al alloy melts,which significantly depresses its strengthening and grain refining *** this work,the destabilization mechanisms of the TiC_(x)particles in Al-Si alloy melt with a composition of Al-7Si-7.5TiC were explored via experiments,first-principles calculations and thermodynamic *** experimental results show that Si atoms diffuse into TiC_(x)and Ti atoms are released into the Al melt to form a Ti-rich transition zone during the insulation of TiC_(x)in Al-Si melt,and the TiAlySiz and Al_(4)C_(3)phases are solidified in the Ti-rich zone and at Ti-rich zone/TiC_(x)interface,*** first principles calculations show that the low formation energy of C vacancies facilitates the rapid diffusion of Si atoms in TiC_(x),while the doping of Si atoms reduces the energy barrier of diffusion of Ti atoms in TiC_(x)and promotes the formation of Ti-rich *** thermodynamic calculations show that the wide crystallization temperature range of the destabilized product TiAlySiz phase is the key to continuous decomposition of TiC_(x)*** addition,the driving force of the main destabilization reaction of TiC_(x)in the Al-Si alloys is about 44 times higher than that in the Al alloys without Si *** indicates that the presence of solute Si remarkably promotes the subsequent decomposition process of TiC_(x)in the Al-Si alloy melts.

关键词： Al-Si alloy TiC_(x)particles Destabilization First principles calculations Thermodynamics

Numerical study of the circular opening effect on mechanical behaviour of rock under confinement

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journal of Rock Mechanics and Geotechnical Engineering 2019年第6期11卷 1201-1210页

作者： y.L.Gui j.L.Shang j.j.Ma Z.y.zhao school of engineering newcastle universitynewcastle upon tynene17ruunited kingdom school of civil and environmental engineering nanyang technological university639798singapore school of civil engineering sun yat-sen universityguangzhou510275china

Opening holes in rock including their size and distribution can affect the performance of rock-related structures.A good understanding on this will contribute to,for example,rock cavern design,and construction,tunnelling,and mining *** improve the understanding,a comprehensive investigation of the opening hole effect on the rock mechanical behaviour under biaxial loading condition is carried out by virtue of a hybrid continuum-discrete element *** specimens with both single hole and multi-hole of various radii are investigated and compared with the cases subjected to uniaxial *** is demonstrated that the confining pressure can increase both the stiffness and strength due to delaying the crack initiation and *** increase due to the confining pressure is more evident for the compressive *** single hole specimens with 0.75 mm radius hole,the increase ratio of the compressive strength is a linear increasing function with width and the increase ratio ranges from 2.15 for the specimen with 3.5 mm width to 2.45 for 10 mm *** the single hole specimen with 10 mm width,the increase ratio starts at 2.13 for the specimen with 0.75 mm radius hole,ascending to the peak of 2.37 for the specimen with 1 mm radius hole,followed by a decline to 2.2 for the specimen with 1.25 mm radius ***,for the multi-hole specimens,the increase ratio varies from 1.66 to *** addition,to verify the influence of confining pressure magnitude on the performance of the rock specimens,totalling 10 confining pressure levels are applied and *** simulation results show that even though there are opening holes in the specimens,the simulated compressive strength generally follows the generalised Hoek-Brown model.

关键词： Rock with opening Simulation Biaxial loading Strength Stiffness

MODELING OF MICROSTRUCTURAL EVOLUTION IN MICROALLOyED STEEL DURING HOT FORGING PROCESS

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Acta Metallurgica Sinica(English Letters) 2006年第4期19卷 279-286页

作者： j. Wang j. Chen Z. zhao X.y. Ruan National Die ＆. Mold CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030 China

The microstractural evolution of microalloyed steel during hot forging process was investigated using physical simulation experiments. The dynamic recrystallized fraction was described by modifying Avrami＇s equation, the parameters of which were determined by single hit compression tests. Double hit compression tests were performed to model the equation describing the static recrystallized fraction, and the obtained predicted values were in good agreement with the measured values. Austenitic grain growth was modeled as： Dinc^5 = D0^5 ＋ 1.6 × 10^32t·exp （ -716870/RT ） using isothermal tests. Furthermore, an equation describing the dynamic recrystallized grain size was given as Ddyn=3771·Z^-0.2. The models of microstructural evolution could be applied to the numerical simulation of hot forging.

关键词： microalloyed forging steel flow stress recrystallized fraction grain size

A New Glucoside from Ceratostigma willmottianum

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Chinese Chemical Letters 1997年第10期8卷 873-874页

作者： yue, jM zhao, y Xu, j Lin, ZW Sun, HD ACAD SINICA KUNMING INST BOTLAB PHYTOCHEMKUNMING 650204PEOPLES R CHINA

Ceratoside A (1), a new compound was isolated from the butanol-soluble fraction of Ceratostigma willmottianum, Its structure was determined by the utilization of 2D-NMR techniques.

关键词： A New Glucoside from Ceratostigma willmottianum CI

Multistage serrated flow behavior of a medium-manganese high-carbon steel

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journal of Iron and Steel Research International 2020年第9期27卷 1064-1072页

作者： j.Chen y.Zhang j.j.Wang C.M.Liu S.X.zhao Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina Shenyang Industrial Transformation Upgrading Promotion Center Shenyang 110083LiaoningChina The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina Central Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China

The deformation mechanisms and the flow stress behavior of a medium-manganese high-carbon steel during cold deformation at a strain rate of 10×5 s^-1 were explored using a universal testing machine,an X-ray diffractometer,a field emission scanning electron microscope and a high-resolution transmission electron *** results show that continuous step-up serrated flow behavior appears after the yielding point,and the true stress-strain curve is roughly divided into five stages based on distinctive densities and amplitudes of *** strengthening mechanisms of the experimental steel involve Cottrell atmosphere,twinning-induced plasticity(TWIP)efect and transformation-induced plasticity(TRIP)*** effect is the dominant deformation mechanism,and deformation twins formed by TWIP effect comprise primary,secondary and ***,TRIP effect arises in the local high-strain *** element plays a key role in the transformation of the deformation mechanism.A small amount of carbide precipitates around twin boundaries lead to the formation of local carbon-poor regions,and Md temperature and stacking fault energy of medium-manganese high-carbon steel are propitious to the occurrence of TRIP *** addition,the contributions of various deformation mechanisms to plasticity are calculated,and that of TWIP effect is the greatest.

关键词： Serrated flow Deformation mechanism Deformation twin Twinning-induced plasticity Transformation-induced plasticity

Twinning behavior of hot extruded AZ31 hexagonal prisms during uniaxial compression

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journal of Magnesium and Alloys 2019年第1期7卷 90-97页

作者： y.R.zhao L.L.Chang j.Guo y.P.jin School of Materials Science and Engineering Shandong UniversityJinanShandong 250061China Key Laboratory for Liquid-Solid Structure Evolution and Processing of Materials Ministry of EducationShandong UniversityJinan 250061China

Hot-extruded magnesium alloy AZ31 bar was cut into hexagonal prisms and then compressed at room temperature with the loading direction parallel to the extrusion direction(ED)or perpendicular to *** effective stress and strain evolution at center and corner region of the hexagonal prisms was simulated by using DEFORM 3D,while microstructure evolution was characterized by electron backscatter diffraction(EBSD).Relationship between twinning behavior and stress-strain evolution during compression at room temperature was *** results indicated that the compressive stress and strain levels at central region of hexagonal prisms were lower than those at the corner *** examination revealed that{10-12}twins activate during the compression and the volume fraction of twins at corner parts were less than that at the central parts,which was attributed to twin thickening and coalescence ***,the EBSD map indicated that the arise of{10-11}contraction twins and{10-11}-{10-12}double twins in compressed samples,especially in the corner region with loading axis perpendicular to ED,which were considered to be related to the high stress level at corner *** dislocation slips led to low-angle boundaries in LA⊥ED and LA//ED.

关键词： Magnesium alloy Simulation Microstructure Twinning Coalescence

Effects of Growth Temperature on Structural and Electrical Properties of Li-N-H Codoped ZnO

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journal of Materials Science & Technology 2013年第2期29卷 154-156页

作者： y.F. Lu Z.Z. ye L.P. Zhu y.j. Zeng j.y. Huang B.H. zhao State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University

Effects of growth temperature on the structural and electrical properties of Li-N-H codoped ZnO thin films grown by DC reactive magnetron sputtering were investigated. Scanning electron microscopy and X-ray diffraction results showed that increasing growth temperature could improve the crystalline quality. But Hall measurement results showed that growth temperature had a nonlinear influence on the electrical property. The variation of electrical properties with the growth temperature was found to be related to the activated concentration of N in ZnO and the evaporation of Li during the growth process, derived from the Hall measurement and the second ion mass spectroscopy measurement.

关键词： ZnO Codoped Growth temperature Structural property Electrical property

Numerical Study of an Annular Gas Turbine Combustor with Dump Diffuser

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journal of Thermal Science 1999年第1期8卷 59-64页

作者： j.X.zhao y.B.Lai DepartmentofPowerEngineering NanjingUniversityofAeronauticsandAstronautics210016NanjingChina Depar

A general numerical method is presented for calculating steady three-dimensional and two-phase turbulent reactive flows with a nonstaggered body-fitted coordinate system in an annular gas turbine combustor with the dump diffuser. The modified two-equation model and the EDC turbulent combustion model are used for the gas phase. The liquid phase equations are solved in a Lagrangian frame of reference by PSIC algorithm. The effect of different velocity profiles at the entry of the prediffuser on combustor flow characteristics is calculated.

关键词： numerical simulation annular combustor dump diffuser 3D body-fitted coordinate two phase combustion.

Compression Stability of Reversed Austenite in 9Ni Steel

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journal of Materials Science & Technology 2012年第6期28卷 558-561页

作者： S.H.Chen M.j.zhao X.y.Li L.j.Rong Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The effect of compressive stress on the stability of reversed austenite in gNi steel was investigated by uni- axial and hydrostatic compression. It was found that the uniaxial compressive pressure promoted the Υ-α transformation, while the hydrostatic pressure suppressed the -Υ-α transformation. The pressure dependent transformation behavior can be explained according to thermodynamic analysis.

关键词： 9Ni steel Martensite Reversed austenite Hydrostatic pressure Uniaxial compressive pressure