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MiCROSTRUCTURAl EVOlUTiON OF AS-CAST ZA27 AllOY DURiNG COMPRESSiVE CREEP

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Acta Metallurgica Sinica(English letters) 2003年第5期16卷 335-341页

作者： x.W.Wei b.l.Shen DepartmentofMaterialsScienceandEngineering SichuanInstituteofTechnologyChengdu610039China DepartmentofMetalScience SichuanUniversityChengdu610065China

Phase transformation and micro structural change of an as-cast ZA27 alloy were investigated during compressive creep by x-ray diffraction technique, SEM and TEM. Compressive creep induced decomposition of α metastable η' phase and a four-phase transformation, α + ε → T' + η and T' → θ, occurred during the compressive creep testing. The occurrence of negative creep in the alloy resulted from the volume expansion caused by the four-phase transformation. A micro structural change was also observed from a lamellar structure into a spheroidized structure in higher creep strain of tested specimens. it provided evidence of compressive creep induced phase transformation which occurred in ageing process.

关键词： microstructure change compressive creep ZA27 alloy

Mechanical properties of gas hydrate-bearing sediments during hydrate dissociation

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Acta Mechanica Sinica 2018年第2期34卷 266-274页

作者： x.H.Zhang D.S.luo x.b.lu l.l.liu C.l.liu institute of Mechanics Chinese Academy of SciencesBeijing 100190China College of Engineering University of Chinese Academy of SciencesBeijing 100049China Key laboratory of Gas Hydrate Ministry of Land and ResourcesQingdao 266071China Qingdao institute of Marine Geology Qingdao 266071China

The changes in the mechanical properties of gas hydrate-bearing sediments(GHbS) induced by gas hydrate(GH) dissociation are essential to the evaluation of GH exploration and stratum instabilities. Previous studies present substantial mechanical data and constitutive models for GHbS at a given GH saturation under the non-dissociated condition. in this paper, GHbS was formed by the gas saturated method, GH was dissociated by depressurization until the GH saturation reached different dissociation degrees. The stress–strain curves were measured using triaxial tests at a same pore gas pressure and different confining pressures. The results show that the shear strength decreases progressively by 30%–90% of the initial value with GH dissociation, and the modulus decreases by 50% –75%. Simplified relationships for the modulus, cohesion, and internal friction angle with GH dissociated saturation were presented.

关键词： Gas hydrate-bearing sediments Dissociation Mechanical properties Shear strength Triaxial test

QUANTiTATiVE STUDY ON GAlVANiC EFFECTS DURiNG CAViTATiON DAMAGE OF 1Cr13 STAiNlESS STEEl

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Acta Metallurgica Sinica(English letters) 2003年第1期16卷 15-21页

作者： x.bai D.b.Sun H.Y.Yu x.l.Zhang Corrosion and Protection Cent. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The influence of the surface galvanic effects of 1Cr13 SS during cavitation damage has been investigated in NaCl solutions. The results show that the solution concentration and area ratio of bubble unacted surface to the bubble-acted surface greatly influence the cavitation damage of the alloy. The surface galvanic effects can speed up the dissolution rate of the alloy, and the mass loss per area of the alloy increases linearly with the area ratio of bubble unacted surface to the bubble acted surface of the alloy.

关键词： galvanic effect cavitation damage area ratio mass loss

On Temperature and Strain Rate Dependent Strain localization behavior in Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy

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Journal of Materials Science & Technology 2013年第3期29卷 273-278页

作者： b.Zhang l.M.lei x.l.Jiang Z.M.Song x.Huang G.P.Zhang Key laboratory for Anisotropy and Texture of Materials(Ministry of Education) Northeastern University Titanium Alloys laboratory Beijing Institute of Aeronautical Materials AViC commercial Aircraft Engine Co. Ltd. Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

Deformation behaviors of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloys with α/β lamellar structure were investigated systematically at different temperatures from room temperature to 950 ~C and different strain rates. Results reveal that when the deformation temperature is higher than a critical temperature of 600℃, an evident transition of deformation behavior from localized shear banding to α/β lamella kinking, flow softening and temperature/strain rate-dependent peak flow stress occurred in the alloy. The critical conditions for the occurrence of internal cracking and strain localization behavior associated with temperature and strain rate were determined.

关键词： Titanium alloy Hot working Temperature Strain rate Shear band

The Potential of Eb Surface Processing within the Aero-space industry

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稀有金属材料与工程 2011年第S4期40卷 155-159页

作者： A l buxton b G i Dance TWi ltd Granta ParkGreat AbingtonCambridgeUK

The ability to control the structure of a surface offers benefits in a wide range of aerospace applications.A novel Eb (Electron beam) materials processing technology developed at TWi,Surfi-Sculpt,addresses this need by using an electron beam to generate precisely defined textured ***-Sculpt offers improved mechanical keying with adjoining parts and consequently has generated interest as a preparation technique for surface coatings and for the joining of composite to *** has the potential to create customised aerodynamically and hydrodynamically enhanced surfaces and appears suitable for the manufacture of novel bearing and seal *** Surfi-Sculpt process has also showed promise in increasing the efficiency of heat exchange *** paper describes the background of the Surfi-Sculpt process and showcases a range of surfaces that have been produced with the *** results of a range of feasibility studies are presented to demonstrate the potential of the technology within the aerospace

关键词： surfi-sculpt aerospace comeld heat exchange

Twinnability Predication for fcc Metals

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Journal of Materials Science & Technology 2011年第2期27卷 97-100页

作者： b.Q.li M.l.Sui S.x.Mao Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China institute of Microstructure and Properties of Advanced Materials Beijing University of TechnologyBeijing 100124China Department of Mechanical Engineering and Materials Science University of PittsburghPittsburghPennsylvania 15261USA

inherent twinnability of face-centered-cubic（fcc） metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation,with which the twinnability of fcc metals can be simply expressed as function of the stacking-fault energy,the unstable stacking-fault energy,and the unstable twinningfault energy of fcc *** predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters.

关键词： Deformation twinning fcc metals Twinnability

Effect of rolling ratios on the microstructural evolution and corrosion performance of an as-rolled Mg-8wt.%li alloy

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Journal of Magnesium and Alloys 2021年第2期9卷 560-568页

作者： b.J.Wang D.K.xu x.Cai Y.x.Qiao l.Y.Sheng School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang110159China Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiangChina Peking University Shenzhen InstituteShenzhen Key Lab Human Tissue Regenerate&RepairShenzhen 518057China

in this work,the influence of rolling ratios on microstructural changes and corrosion behavior of an as-rolled Mg-8 wt.%li alloy in0.1 mol/l Na Cl solution has been *** revealed that with the rolling ratio being increased from 3 to 10,theα-Mg phases were elongated and fragmented,whilst the area fraction of exposedβ-li phases ***,the corrosion performance of the alloy decreased with the increased rolling *** all the samples,their corrosion processes were quite similar and can have two *** the initial stage with the samples being immersed for less than 6 h,the corrosion mainly occurred inβ-li *** the samples were immersed for longer than 6 h,the corrosion attack transferred toα-Mg phases and the hydrogen evolution rate was accelerated.

关键词： Mg-li alloys Wrought Microstructure Corrosion performance

Formability of Materials with Small Tools in incremental Forming

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Chinese Journal of Mechanical Engineering 2020年第4期33卷 150-158页

作者： Hongyu Wei G.Hussain x.Shi b.b.l isidore Mohammed Alkahtani Mustufa Haider Abidi College Mechanical&Electrical Engineering Nanjing University of Aeronautics&AstronauticsNanjingPeople’s Republic of China Faculty of Mechanical Engineering GIK Institute of Engineering Sciences&TechnologyTopi 23460Pakistan College of Mechanical Engineering Shanghai University of Engineering ScienceShanghaiPeople’s Republic of China bradenburg University of Technology CottbusGermany industrial Engineering Department College of EngineeringKing Saud UniversityRiyadh 11421Saudi Arabia Advanced Manufacturing institute King Saud UniversityRiyadh 11421Saudi Arabia

Single point incremental forming(SPiF)is an innovative sheet forming process with a high economic *** formability in this process can be maximized by executing forming with a tool of specific small radius,regarded as threshold critical *** value has been reported as 2.2 mm for 1 mm thick sheet ***,with a change in the forming conditions specifically in the sheet thickness and step size,the critical radius is likely to alter due to a change in the bending *** main aim of the present study is to undertake this point into account and develop a relatively generic *** study is composed of experimental and numerical *** maximum wall angle(θmax)without sheet fracturing is regarded as sheet formability.A number of sheet materials are formed to fracture and the trends correlating formability with normalized radius(i.e.,R/To where R is the tool-radius and To is the sheet thickness)are *** trends confirm that there is a critical tool-radius(Rc)that maximizes the formability in ***,it is found that the critical radius is not fixed rather it shows dependence on the sheet thickness such that Rc=βTo,whereβvaries from 2.2 to 3.3 as the thickness increases from 1 mm to 3 *** critical radius,however,remains insensitive to variation in step size ranging from 0.3 mm to 0.7 *** is also observed that the selection of tool with Rbility window not only on the higher side but also on the lower *** higher limit,as revealed by the experimental and FEA results,diminishes due to excessive shearing because of in-plane biaxial compression,and the lower limit reduces due to pillowing in the bottom of *** new tool-radius condition proposed herein study would be helpful in maximizing the formability of materials in SPiF without performing experimental trials.

关键词： incremental forming Critical tool-radius Formability curve Finite element analysis

Simulations of deformation and damage processes of SiCp/Al composites during tension

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Journal of Materials Science & Technology 2018年第4期34卷 627-634页

作者： J.F.Zhang x.x.Zhang Q.Z.wang b.l.xiao Z.Y.Ma Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China

The deformation, damage and failure behaviors of 17 vol.% SiCp/2009Ai composite were studied by micro- scopic finite element （FE） models based on a representative volume element （RVE） and a unit cell. The RVE having a 3D realistic microstructure was constructed via computational modeling technique, in which an interface phase with an average thickness of 50 nm was generated for assessing the effects of interracial properties. Modeling results showed that the RVE based FE model was more accurate than the unit cell based one. based on the RVE, the predicted stress-strain curve and the fracture morphology agreed well with the experimental results. Furthermore, lower interface strength resulted in lower flow stress and ductile damage of interface phase, thereby leading to decreased elongation. it was revealed that the stress concentration factor of SiC was -2.0： the average stress in SiC particles reached -1200 MPa, while that of the composite reached -600 MPa.

关键词： Metal matrix composites (MMCs) Fracture Finite element (FE) analysis interfacial strength Tensile strength Representative volume element (RVE)