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Microstructure analysis and mechanical characteristics of tungsten inert gas and metal inert gas welded AA6082-T6 tubular joint: A comparative study 被引量:2
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作者 E.R.IMAM FAUZI M.S.CHE JAMIL +1 位作者 Z.SAMAD P.MUANGJUNBUREE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第1期17-24,共8页
The present study is aimed to compare the microstructure characteristics and mechanical properties of AA6082 in T6 condition of tubular joints fabricated by tungsten inert gas welding (TIG) and metal inert gas weldi... The present study is aimed to compare the microstructure characteristics and mechanical properties of AA6082 in T6 condition of tubular joints fabricated by tungsten inert gas welding (TIG) and metal inert gas welding (MIG) processes. The effect of welding processes was analysed based on optical microscopy image, tensile testing, and Vickers micro-hardness measurements. The results showed that the tensile strengths of the TIG-welded joints were better than those of the MIG-welded joints, due to the contribution of fine equiaxed grains formation with narrower spacing arms. In terms of joint efficiency, the TIG process produced more reliable strength, which was about 25% higher compared to the MIG-joint. A significant decay of hardness was recorded in the adjacent of the weld bead zone, shown in both joints, related to phase transformation, induced by high temperatures experienced by material. A very low hardness, which was about 1.08 GPa, was recorded in the MIG-weldcd specimens. The extent of the heat-affected-zone (HAZ) in the MIG-welded joints was slightly wider than those of the TIG-welded specimens, which corresponded with a higher heat input per unit length. 展开更多
关键词 AA6082 aluminium alloy tungsten inert gas (TIG) metal inert gas (MIG) mechanical properties microstructure analysis
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Preparation and Microstructure Analysis of High Strength Cementitious Materials Containing Metakaolin
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作者 YU R SHUI Z H DONG J 《武汉理工大学学报》 CAS CSCD 北大核心 2010年第17期117-122,136,共7页
The preparation and microstructure analysis of high strength cementitious materials containing metakaolin (MK) was studied in this paper. The MK was prepared firstly,and then was mixed with fly ash,ground blast furnac... The preparation and microstructure analysis of high strength cementitious materials containing metakaolin (MK) was studied in this paper. The MK was prepared firstly,and then was mixed with fly ash,ground blast furnace slag,quartz powder and cement with different percentage to produce high strength cementitious materials. After cured under different environment,the compressive strength of such materials was tested. Techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM) were further employed to identify the composition and microstructure. The results obtained reveal that the compressive strength of such materials mainly effected by component of raw materials,the water binder ratio (W/B) and the curing regime. When the three factors above are optimized,the compressive strength of such materials can get to 156 MPa in maximum. The X-ray diffraction analysis and the scanning electron microscopic images indicated that under optimal curing condition,more raw materials can take chemical reaction and the microstructure is dense to yield good mechanical properties. 展开更多
关键词 PREPARATION microstructure analysis high strength cementitious materials METAKAOLIN
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Co-deposition of Co-Ni alloys and their microstructure analysis by PoSAP
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作者 R.A.D.Mackenzie G.D.W.Smith 《Chinese Science Bulletin》 SCIE EI CAS 1997年第23期2013-2014,共2页
PULSED-co-electrodeposition (PCD) is a new and promising technique for producing alloymaterials of nanometer grain size. In this letter, Co-Ni alloys were produced by PCD, and theeffect of CO<sup>+2</sup>... PULSED-co-electrodeposition (PCD) is a new and promising technique for producing alloymaterials of nanometer grain size. In this letter, Co-Ni alloys were produced by PCD, and theeffect of CO<sup>+2</sup> ion concentration in the depositing baths on the Co content and the microstruc-ture in the corresponding deposit was studied by the position sensitive atom probe (PoSAP),TEM and X-ray diffraction. The Co-Ni phase diagram shows that, at room temperature,there are two phases in Co-Ni alloys, one is εCo with hcp lattice, the other is αCo of fcc lat-tice. A Co-Ni alloy with a Ni content below 27% consists of single εCo, beyond 36% consistsof single αCo, in between consists of εCo + αCo. The examination results of TEM, SEM andX-ray diffraction indicated that the Co-Ni deposits with average grain size of 70 nm and thick- 展开更多
关键词 Co-deposition of Co-Ni alloys and their microstructure analysis by PoSAP NI
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Analysis of χ Phase Precipitation in Aged 2205 Duplex Stainless Steel 被引量:1
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作者 刘和平 SUN Hu'er +3 位作者 LIU Bin LI Dazhao SUN Fenger ZHANG Yongtao 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第3期591-595,共5页
Analysis ofZ phase precipitation in 2205 duplex stainless steel aged at 700 and 750 ~C has been investigated systematically. The experimental results showed that X phase forms prior to the precipitation of δ phase an... Analysis ofZ phase precipitation in 2205 duplex stainless steel aged at 700 and 750 ~C has been investigated systematically. The experimental results showed that X phase forms prior to the precipitation of δ phase and disappears once tr phase starts to precipitate. This phenomenon indicates that a phase nucleated and consumed the Z phase. The δ phase nucleated mairdy at ferrite/austenite interface and grew inwards into the ferrite phase. The morphology of a phase reveals a coral-like structure at the temperature of 700 ℃ for 120 min followed by quenching in water. The decomposition of ferrite occurs via the following eutectoid reaction: F---*o'+y2. The selected area diffraction pattern of zone axes is[3 1 3-][3 1 3], indicating a characteristic orientation relationship between X phase and δ-ferrite. 展开更多
关键词 duplex stainless steel X phase tr phase microstructure analysis
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Long-Term Performance and Microstructural Characterization of Dam Concrete in the Three Gorges Project
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作者 Chen Lyu Cheng Yu +3 位作者 Chao Lu Li Pan Wenwei Li Jiaping Liu 《Engineering》 SCIE EI CAS CSCD 2024年第2期237-262,共26页
This study investigates the long-term performance of laboratory dam concrete in different curing environments over ten years and the microstructure of 17-year-old laboratory concrete and actual concrete cores drilled ... This study investigates the long-term performance of laboratory dam concrete in different curing environments over ten years and the microstructure of 17-year-old laboratory concrete and actual concrete cores drilled from the Three Gorges Dam.The mechanical properties of the laboratory dam concrete,whether cured in natural or standard environments,continued to improve over time.Furthermore,the laboratory dam concrete exhibited good resistance to diffusion and a refined microstructure after 17 years.However,curing and long-term exposure to the local natural environment reduced the frost resistance.Microstructural analyses of the laboratory concrete samples demonstrated that moderate-heat cement and fine fly ash(FA)particles were almost fully hydrated to form compact micro structures consisting of large quantities of homogeneous calcium(alumino)silicate hydrate(C-(A)-S-H)gels and a few crystals.No obvious interfacial transition zones were observed in the microstructure owing to the longterm pozzolanic reaction.This dense and homogenous microstructure was the crucial reason for the excellent long-term performance of the dam concrete.A high FA volume also played a significant role in the microstructural densification and performance growth of dam concrete at a later age.The concrete drilled from the dam surface exhibited a loose microstructure with higher microporosity,indicating that concrete directly exposed to the actual service environment suffered degradation caused by water and wind attacks.In this study,both macro-performance and microstructural analyses revealed that the application of moderate-heat cement and FA resulted in a dense and homogenous microstructure,which ensured the excellent long-term performance of concrete from the Three Gorges Dam after 17 years.Long-term exposure to an actual service environment may lead to microstructural degradation of the concrete surface.Therefore,the retained long-term dam concrete samples need to be further researched to better understand its microstructural evolution and development of its properties. 展开更多
关键词 Three Gorges Dam Long-term performance Microstructural analysis Moderate-heat cement Fly ash
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Increasing the toughness while reducing the viscosity of carbon nanotube/ polyether imide/polyether ether ketone nanocomposites
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作者 SONG Jiu-peng ZHAO Yan +3 位作者 LI Xue-kuan XIONG Shu LI Shuang WANG Kai 《新型炭材料(中英文)》 SCIE EI CAS CSCD 北大核心 2024年第4期715-728,共14页
Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether im... Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether imide(PEI)were pre-pared by a direct wet powder blending method using a vertical injection molding machine.The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50%while producing an increase in the toughness of the nanocom-posites,whose strain to failure increased by 129%,and fracture energy increased by 97%.The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance.This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites. 展开更多
关键词 NANOCOMPOSITES Mechanical properties Rheological properties Microstructural analysis
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Role of heat balance on the microstructure evolution of cold spray coated AZ31B with AA7075 被引量:3
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作者 Bahareh Marzbanrad Mohammad Hadi Razmpoosh +1 位作者 Ehsan Toyserkani Hamid Jahed 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2021年第4期1467-1478,共12页
A promising solid-state coating mechanism based on the cold spray technique provides highly advantageous conditions on thermal-sensitive magnesium alloys.To study the effect of heat balance in cold spray coating on mi... A promising solid-state coating mechanism based on the cold spray technique provides highly advantageous conditions on thermal-sensitive magnesium alloys.To study the effect of heat balance in cold spray coating on microstructure,experiments were designed to successfully coat AA7075 on AZ31B with two different heat balance conditions to yield a coated sample with tensile residual stress and a sample with compressive residual stress in both coating and substrate.The effects of coating temperature on the microstructure of magnesium alloy and the interfaces of coated samples were then analyzed by SEM,EBSD,TEM in high-and low-heat input coating conditions.The interface of the AA7075 coating and magnesium alloy substrate under both conditions consists of a narrow-band layer with very fine grains,followed by columnar grains of magnesium that have grown perpendicular to the interface.At higher temperatures,this layer became wider.No intermetallic phase was detected at the interface under either condition.It is shown that the microstructure of the substrate was affected by coating temperature,leading to stress relief,dynamic recrystallization and even dynamic grain growth of magnesium under high temperature.Reducing the heat input and increasing the heat transfer decreased microstructural changes in the substrate. 展开更多
关键词 Cold spraying Heat balance Microstructural analysis Coating interface Magnesium Alloy AZ31B Residual Stress
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Application of Nanotechnology in Soil Stabilization
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作者 Amit Kumar Kiran Devi 《Journal of Building Material Science》 2023年第2期25-36,共12页
Nano-technology is expanding its horizon in various science and technology fields.In civil engineering,soil is a complex material and used for various functions and applications.Meanwhile,sometimes an effective soil s... Nano-technology is expanding its horizon in various science and technology fields.In civil engineering,soil is a complex material and used for various functions and applications.Meanwhile,sometimes an effective soil stabilization technique is needed to fulfil the site criteria and can be achieved by adopting various methods e.g.,physical,chemical,thermal or reinforcement using geotextiles and fabrics.The mechanism of soil stabilization using nanomaterials is still unexplored and open to prospective researchers.The present article attempts to touch and explore the possibilities of nano-technology in soil improvement and its applications in various civil engineering works.Microstructural analysis of the nanomaterials treated soils using the latest equipment has also been discussed.The study interprets that the use of nano materials is still limited,due to their high cost and sophisticated handling procedures.Though the use of nanoparticles in soil stabilization results in extraordinary improvements in various soil properties,the improved soil properties could be utilized for various geotechnical projects.The present study bridges the past findings to the present scenario of nanomaterials in soil improvement. 展开更多
关键词 Nano particles Fine soils Geotechnical engineering Microstructural analysis Field application
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Dynamic regimes of cemented backfill at early-age 被引量:4
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作者 LIU Zhi-yi GAN De-qing GAN Ze 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第7期2079-2090,共12页
In view of the mechanics characteristic of cemented tailings backfill(CTB)at early age,the separation Hopkinson pressure bar test device was used to explore the effects of curing age and impact energy.A total of 48 CT... In view of the mechanics characteristic of cemented tailings backfill(CTB)at early age,the separation Hopkinson pressure bar test device was used to explore the effects of curing age and impact energy.A total of 48 CTB samples with diameter of 50 mm and length of 25 mm were prepared with curing ages of 3,5,7 and 9 d.Impact tests under different impact energy(10,20,30 and 40 J)were carried out.The microstructure of CTB at different ages was analyzed by scanning electron microscopy(SEM).The results show that,the curing age mainly affects the mechanical properties and internal structure of early-age CTB.With increasing curing age,the mechanical properties of early-age CTB change from viscoelasticity to brittleness.The impact energy mainly affects the response of dynamic peak compressive strength to strain rate.Under low strain rate,the structure of CTB is broken,but still has bearing capacity,affecting the formation of later strength.It is concluded that the structural loses completely under the action of high strain rate.Therefore,the control of impact energy and the protection of curing age should be fully considered in actual production process. 展开更多
关键词 early-age backfill curing age impact energy mechanical property microstructure analysis
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Laboratory-scale model of carbon dioxide deposition for soilstabilisation 被引量:2
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作者 Mohammad Hamed Fasihnikoutalab Afshin Asadi +3 位作者 Bujang Kim Huat PaulWestgate Richard JBall Shahram Pourakbar 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2016年第2期178-186,共9页
Olivine sand is a natural mineral,which,when added to soil,can improve the soil’s mechanical properties while also sequester carbon dioxide(CO2)from the surrounding environment.The originality of this paper stems fro... Olivine sand is a natural mineral,which,when added to soil,can improve the soil’s mechanical properties while also sequester carbon dioxide(CO2)from the surrounding environment.The originality of this paper stems from the novel two-stage approach.In the first stage,natural carbonation of olivine and carbonation of olivine treated soil under different CO2pressures and times were investigated.In this stage,the unconfined compression test was used as a tool to evaluate the strength performance.In the second stage,details of the installation and performance of carbonated olivine columns using a laboratory-scale model were investigated.In this respect,olivine was mixed with the natural soil using the auger and the columns were then carbonated with gaseous CO2.The unconfined compressive strengths of soil in the first stage increased by up to 120% compared to those of the natural untreated soil.The strength development was found to be proportional to the CO2pressure and carbonation period.Microstructural analyses indicated the presence of magnesite on the surface of carbonated olivinetreated soil,demonstrating that modified physical properties provided a stronger and stiffer matrix.The performance of the carbonated olivine-soil columns,in terms of ultimate bearing capacity,showed that the carbonation procedure occurred rapidly and yielded a bearing capacity value of 120 k Pa.Results of this study are of significance to the construction industry as the feasibility of carbonated olivine for strengthening and stabilizing soil is validated.Its applicability lies in a range of different geotechnical applications whilst also mitigates the global warming through the sequestration of CO2. 展开更多
关键词 OLIVINE Soil stabilisation CO_2 deposition Climate change Unconfined compressive strength microstructure analysis
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MICROCOMPUTER PICTURE PROCESSING SYSTEM OF CAST-IRON METALLOGRAPHIC STRUCTURE 被引量:1
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作者 Wang Zhiping Lu Yang Xu Jianling Gansu University of Technology 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 1997年第4期45-49,共3页
The development of computer picture processing technique in metallography analysis is dealed with and a picture processing procedure fit to metallography analysis is developed. The image processing of nodular cast iro... The development of computer picture processing technique in metallography analysis is dealed with and a picture processing procedure fit to metallography analysis is developed. The image processing of nodular cast iron is carried out with this system 展开更多
关键词 METALLOGRAPHY Nodular cast iron Image processing MICROCOMPUTER microstructure analysis
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Effects of Carbonation on Micro Structures of Hardened Cement Paste 被引量:2
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作者 柳俊哲 yao senyuan +2 位作者 ba mingfang he zhimin 李玉顺 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第1期146-150,共5页
In order to investigate the effects of carbonation on the microstructure of cement concrete,the carbonation depth and microstructure of cement paste with 0.3,0.4 and 0.5 water/cement ratio after 7,14,21 and 28 d accel... In order to investigate the effects of carbonation on the microstructure of cement concrete,the carbonation depth and microstructure of cement paste with 0.3,0.4 and 0.5 water/cement ratio after 7,14,21 and 28 d accelerated carbonation were studied respectively.The results showed that with the increase of waterto-cement ratio and carbonation age,the carbonation depth was deepened with faster early carbonation speed and slower later carbonation rate.Carbonation densified the structure of hardened cement stone with refinement of pore structure and reduced porosity.Then,during the carbonation process from the surface to the inside of carbonation area,it was prone to form micro-cracks extending to the interior specimen,resulting in cement paste carbonation depth uneven.It is further illustrated that the color reaction method using phenolphthalein solution combined with X-CT and X-ray diffraction analysis is much more reasonable to evaluate the cement concrete carbonation degree.Moreover,during carbonation process sulfur element in cement paste migrated to the area un-carbonated and the concentrated shape of sulfur element is consistent with the coloring region in carbonation interface.Finally it was identified that carbonation not only reduced the p H value in cement concrete but also made prone to crack in carbonation zone,which increased the probability of reinforcement corrosion. 展开更多
关键词 hardened cement paste carbonation sulfur microstructure X-CT analysis
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Coupling stiffening effect of carbon nanotubes on modulus of nanograined metals:Mechanism and multiscale modeling
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作者 WANG Fei LI Li +1 位作者 WANG XueLin HU YuJin 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2024年第11期3513-3523,共11页
A quantitative relationship between grain size and Young's modulus of metal composites has not been established by considering the coupling effect of the reinforcements on microstructural deformation.The objective... A quantitative relationship between grain size and Young's modulus of metal composites has not been established by considering the coupling effect of the reinforcements on microstructural deformation.The objective of this study is to investigate the mechanism of deformation coordination between the carbon nanotube and the composite microstructure using molecular dynamics simulations.Through the analysis of stress contributions from grain boundaries and grains,a grain size-dependent continuum model for the pure metal modulus is established.On this basis,a predictive model for the modulus of metallic composites is developed by considering the coupling deformation between carbon nanotubes and the grains.The proposed model is capable of accurately capturing the relationship between grain size and the modulus of metal composites.This study provides a guideline for microstructure-dependent multiscale modeling. 展开更多
关键词 nanograined metal carbon nanotube molecular dynamics microstructure analysis grain boundary Young's modulus
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Dispersion effect of nano-structure pyrolytic carbon on mechanical,electrical,and microstructural characteristics of cement mortar composite
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作者 N.K.Karthikeyan S.Elavenil 《International Journal of Smart and Nano Materials》 SCIE EI 2024年第3期534-578,共45页
In material science,converting waste into nanomaterials by green technologies highlights the interest in producing sus-tainable carbon nanomaterial(SCN).This study first-ever uti-lized tyre-char as a Nano-Structure Py... In material science,converting waste into nanomaterials by green technologies highlights the interest in producing sus-tainable carbon nanomaterial(SCN).This study first-ever uti-lized tyre-char as a Nano-Structure Pyrolytic Carbon(NSPC)to develop electrically conductive composites.Unlike other car-bon nanomaterials,the efficiency of NSPC particle as an SCN in developing electrically conductive composites was investi-gated in terms of dispersion,mechanical,water absorption,electrical resistivity,and microstructure.The results of sedi-mentation and zeta potential(-19 mV)showed the excellent dispersion of NSPC particle in water with the combined effect of superplasticizer and ultrasonication.The compressive(40.37%)and flexural strength(10.76%)than that of plain cement mortar composite(CMC)is achieved with 2 wt.%and 1.5 wt.%of NSPC particle,respectively.The water absorption rate and volume of permeable voids were reduced,exhibiting less agglomerations.The percolation zone of AC and DC resis-tivity of NSPC composite ranges between 1 and 2 wt.%,and the established percolation threshold is at 2 wt.%.XRD analysis showed C-S-H formation consistently increased with curing age,and HR-SEM with EDAX analysis exhibits the dense micro-structure and well-distributed NSPC particle at the nanoscale.These experimental outcomes significantly enhanced the relia-bility and provided a framework for tailoring NSPC particle as SCN for developing electrically conductive composite. 展开更多
关键词 Sustainable nanomaterial DISPERSION mechanical properties electrical resistivity microstructure analysis
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Structural,optical,electrical,and dielectric relaxation properties of rare earth containing sodium bismuth titanate Na_(0.5)Bi_(0.5)TiO_(3) perovskite:Effect of ionic radius 被引量:1
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作者 Rajdip Roy Abhigyan Dutta 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第2期383-391,I0006,共10页
The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.... The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE^(3+)(RE=La,Sm,Dy,and Ho) on structural and various physical properties of sodium bismuth titanate(Na_(0.5)B_(0.5)TiO_(3),NBT) based perovskite nanomaterials.The X-ray diffraction data indicate the successful formation of the rhombohedral phase(space group R3c) of NBT nano perovskite incorporated with various rare earth ions in Bi-site.The lattice parameters were found to increase linearly with the ionic radius of the dopant cation.The ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared compositions.The grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic radius.Field emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and stoichiometry.The UV-Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap,which unfolds the application of NBT-based perovskite as photoactive material.The ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius,i.e.,La-doped NBT compound,exhibits the highest dc and bulk conductivity with the lowest activation energy.The frequency-dependent dielectric data follows Havriliak-Negami(HN) formalism and non-Debye type relaxation phenomena.Results also indicate that La-doped NBT composition exhibits the highest dielectric strength value.Thus,this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural,optical,and electrical properties. 展开更多
关键词 Rare earth doped NBT Microstructural analysis Optical band gap AC Conductivity Dielectric relaxation Rare earths
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Influence of a non-rotating shoulder on heat generation,microstructure and mechanical properties of dissimilar AA2024/AA7050 FSW joints 被引量:6
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作者 Alessandro Barbini Jan Carstensen Jorge F.dos Santos 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第1期119-127,共9页
Friction stir welding (FSW) and stationary shoulder friction stir welding (SSFSW) were carried out for the butt joining of dissimilar AA2024-T3 and AA7050-T7651 aluminium alloys with thicknesses of 2 mm. A compari... Friction stir welding (FSW) and stationary shoulder friction stir welding (SSFSW) were carried out for the butt joining of dissimilar AA2024-T3 and AA7050-T7651 aluminium alloys with thicknesses of 2 mm. A comparison between the two processes was performed by varying the welding speed while keeping the rotational speed constant, Through the analysis of the force and torque produced during welding and a simple analytical model, it was possible to show that in SSFSW there is more effective coupling with the tool and the heat produced is more efficiently distributed. This process decreases both the welding area and the diffusion at the interface of the two alloys compared with FSW. The minimum microhardness occurred at the advancing side (AS) at the interface between the thermo-mechanically affected zone (TMAZ) and the stir zone (SZ) in both processes, although the decrease was more gradual in SSFSW. This interface is also where all specimens failed for both welding technologies. An increase in tensile strength was measured in SSFSW compared with standard FSW. Furthermore, it was possible to establish the mechanical performance of the material in the fracture zone using digital image correlation. 展开更多
关键词 Stationary shoulder friction stir welding Friction stir welding Dissimilar welded joints Process analysis microstructure analysis Mechanical behaviour
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Laser ablation mechanism and performance of glass fiber-reinforced phenolic composites:An experimental study and dual-scale modelling
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作者 Ran BI Pengfei SHEN +4 位作者 Longyu ZHU Zhengzheng MA Chuyang LUO Yongfeng LI Lijian PAN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第8期470-485,共16页
Both experimental and simulation approaches were employed to investigate the laser ablation mechanism and performances of Glass Fiber Reinforced Phenolic Composites(GFRP).During the ablation process,the difference in ... Both experimental and simulation approaches were employed to investigate the laser ablation mechanism and performances of Glass Fiber Reinforced Phenolic Composites(GFRP).During the ablation process,the difference in thermal conductivities of the glass fibers and the resin matrix as well as their discrepant physical and chemical reactions form a conical ablation morphology.The formation of a residual carbon layer effectively mitigates the ablation rate in the thickness direction.A higher power density results in a faster ablation rate,while a longer irradiation time leads to a larger ablation pit diameter.To account for the variation in thermal conductivity between the fiber and resin,a macro-mesoscale model was developed to differentiate the matrix from the fiber components.Finite element analysis revealed that laser irradiation leads to phenolic decomposition,glass fiber melting vaporization,and residual carbon skeleton evaporation.The dual-scale model exhibits precise prediction capabilities concerning the laser ablation process of GFRP,and its accuracy is confirmed through the comparison of simulation and experimental results for the GFRP laser ablation process.This model provides a feasible method for performance evaluation and lifetime prediction of GFRP subjected to continuous wave laser irradiation. 展开更多
关键词 Polymer-matrix composites Continuous-wave laser Microstructural analysis Ablation mechanism Finite element method
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Microstructure and Fracture Behavior of 316L Austenitic Stainless Steel Produced by Selective Laser Melting 被引量:49
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作者 R.Casati J.Lemke M.Vedani 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第8期738-744,共7页
Selective laser melting is an additive manufacturing method based on local melting of a metal powder bed by a high power laser beam. Fast laser scans are responsible for severe thermal gradients and high cooling rates... Selective laser melting is an additive manufacturing method based on local melting of a metal powder bed by a high power laser beam. Fast laser scans are responsible for severe thermal gradients and high cooling rates which produce complex hydrodynamic fluid flow. These phenomena affect crystal growth and orientation and are believed to be the cause of material spattering and microstructural defects, e.g. pores and incompletely melted particles. In this work, the microstructure and texture of 316L bars built along two different orientations and the effect of different distribution of defects on their mechanical response and failure mechanisms were investigated. Partially molten powder particles are believed to be responsible for the scattering in elongation to failure, reduced strength, and premature failure of vertical samples. 展开更多
关键词 AISI 316L Additive manufacturing Selective laser melting Microstructural analysis Fracture behavior
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Quantitative Study on Nonmetallic Inclusion Particles in Steels by Automatic Image Analysis With Extreme Values Method 被引量:7
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作者 Cássio Barbosa José Brant de Campos +1 位作者 Jneo Lopes do Nascimento Iêda Maria Vieira Caminha 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2009年第4期18-21,32,共5页
The presence of nonmetallic inclusion particles which appear during steelmaking process is harmful to the properties of steels, which is mainly as a function of some aspects such as size, volume fraction, shape, and d... The presence of nonmetallic inclusion particles which appear during steelmaking process is harmful to the properties of steels, which is mainly as a function of some aspects such as size, volume fraction, shape, and distribution of these particles. The automatic image analysis technique is one of the most important tools for the quantitative determination of these parameters. The classical Student approach and the Extreme Values Method (EVM) were used for the inclusion size and shape determination and the evaluation of distance between the inclusion particles. The results thus obtained indicated that there were significant differences in the characteristics of the inclusion particles in the analyzed products. Both methods achieved results with some differences, indicating that EVM could be used as a faster and more reliable statistical methodology. 展开更多
关键词 image analysis steel microstructure nonmetallic inclusion
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Solidification Studies of 3003 Aluminium Alloys with Cu and Zr Additions 被引量:10
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作者 Majed M.R.Jaradeh Torbjorn Carlberg 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2011年第7期615-627,共13页
The effects of Cu and Zr additions, on the microstructure formation, precipitation and ingot cracking, in commercial 3003 Al alloys have been studied. The investigation was carried out by characterizing the grain stru... The effects of Cu and Zr additions, on the microstructure formation, precipitation and ingot cracking, in commercial 3003 Al alloys have been studied. The investigation was carried out by characterizing the grain structure in DC-cast rolling ingots, and studying the solidification microstructure of Bridgman directionally solidified samples. To better understand the influence of the different Cu and Zr contents on the phase precipitations, differential thermal analysis (DTA) experiments were performed. Results from the ingot microstructure analysis show that in commercial alloys with relatively high contents of Cu and Zr, no significant differences in measured grain sizes compared to conventional 3003 Al alloys could be found. However, only Zr containing alloys exhibited significantly larger grain sizes. Increased grain refiner and/or titanium additions could compensate for the negative effects on nucleation normally following Zr alloying. Different types of precipitates were observed. Based on DTA experiments, increased Cu and Zr contents resulted in the formation of Al2Cu phase, and increased solidification range. It was also found that increased Mn content favors an early precipitation of Al6(Mn,Fe) giving relatively coarse precipitates. It was concluded that the Cu alloying has a detrimental effect on hot tearing. 展开更多
关键词 Aluminium 3003 Al-Cu-Zr alloys microstructure analysis Directional solidification Differential thermal analysis (DTA) CRACKING Hot tearing PRECIPITATION
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