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A Brief Introduction of Macrostructures Theory 认领 引用
1
作者 王丽波 《海外英语》 2012年第15期150-151,共2页
In recent years,numerous textual studies have appeared.However,the majority of them concentrated on the study of cohesion and coherence of sentences.Van Dijk(1977,1980),Holland famous linguist,put forward"Macrost... In recent years,numerous textual studies have appeared.However,the majority of them concentrated on the study of cohesion and coherence of sentences.Van Dijk(1977,1980),Holland famous linguist,put forward"Macrostructures"which provide us with a theo retical basis to study macrostructure of texts.The paper aims to introduce it in very detail and make it known to all the English learners. 展开更多
关键词 macrostructures textual studies
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Acoustic properties of closed-cell aluminum foams with different macrostructures 认领 引用 被引量：7
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作者 Xingchuan Xia Zan Zhang +4 位作者 Weimin Zhao Chong Li Jian Ding Chenxi Liu Yongchang Liu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第11期1227-1234,共8页
As structural materials, closed-cell aluminum foams possess obvious advantages in product dimension, strength and process economics compared with open cell aluminum foams. However, as a kind of structure-function inte... As structural materials, closed-cell aluminum foams possess obvious advantages in product dimension, strength and process economics compared with open cell aluminum foams. However, as a kind of structure-function integration materials, the application of closed-cell aluminum foams has been restricted greatly in acoustic fields due to the difficulty of sound wave penetration. It was reported that closed-cell foams with macrostructures have important effect on the propagation of sound waves. To date, the relationship between macrostructures and acoustic properties of commercially pure closedcell aluminum foams is ambiguous. In this work, different perforation and air gap types were designed for changing the macrostructures of the foam. Meanwhile, the effect of macrostructures on the sound absorption coefficient and sound reduction index were investigated. The results showed that the foams with half-hole exhibited excellent sound absorption and sound insulation behaviors in high frequency range（〉2500 Hz）. In addition, specimens with air gaps showed good sound absorption properties in low frequency compared with the foams without air gaps. Based on the experiment results, propagation structural models of sound waves in commercially pure closed-cell aluminum foams with different macrostructures were built and the influence of macrostructures on acoustic properties was discussed. 展开更多
关键词 Closed-cell aluminum foam Sound absorption Sound insulation Macrostructure
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Macrostructures and mechanical properties of ultrasonic-assisted friction stir welding joint of 2024-T3 aluminium alloy 认领 引用 被引量：1
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作者 高嵩 钟益斌 武传松 《China Welding》 EI CAS 2015年第3期24-28,共5页
In friction stir welding of aluminum alloys, tunnel defect may occur due to insufficient plastic material flow caused by lower heat input in the weld region. The inadequacy in heat input is due to improper selection o... In friction stir welding of aluminum alloys, tunnel defect may occur due to insufficient plastic material flow caused by lower heat input in the weld region. The inadequacy in heat input is due to improper selection of friction stir welding tool and process parameters. Ultimately, such defects degrade the properties of weld and may pose serious concerns towards the integrity and safety of the weld component. In order to improve the properties of weld joints, an ultrasonic-assisted friction stir welding device has been configured where ultrasonic energy is transferred from an ultrasonic unit directly into one of the workpieces near the tool. Using this configuration, ultrassonic-assisted friction stir welding was conducted on 6 mm thick 2024- 73 aluminum alloy sheets. The macrostructure and mechanical properties of these welds were compared with the welds of this alloy prepared by conventional friction stir welding using identical process parameters. The results show that the welding speed can be increased while satisfactory weld quality is still ensured. The ultrasonic energy transferred in this configuration could enlarge the volume of weld nugget zone. Also, the influence of ultrasonic energy on the suppression or elimination of the tunnel defect is quite apparent. However, any beneficial effects of ultrasonic vibration on the tensile strength and the elongation of the joint were less obvious in this configuration. 展开更多
关键词 ultrasonic vibration friction stir welding macrostructure mechanical properties
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Statistical and experimental study of effects of process parameters on Ti-6Al-4V coaxial wire-feed laser cladding 认领 引用 被引量：2
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作者 Fan Liu Shaoshan Ji +2 位作者 Tuo Shi Shihong Shi Geyan Fu 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2026年第1期31-42,共12页
Three-beam wire-feed laser cladding,which generates a uniform energy distribution with a wire vertically fed into the molten pool,is a promising additive manufacturing technology.In this study,an experimental investig... Three-beam wire-feed laser cladding,which generates a uniform energy distribution with a wire vertically fed into the molten pool,is a promising additive manufacturing technology.In this study,an experimental investigation and a statistical analysis of Ti-6Al-4V wire cladding using three-beam laser coaxial wire-feed cladding technology coupled with a 2 kW continuous fiber laser were carried out.The influences of the main parameters,including the laser power,wire feeding speed,and laser scanning speed,on the cladding geometry and process were investigated.The prediction models correlating the process parameters and clad geometry were developed via the response surface methodology(RSM).The models were checked using analysis of variance(ANOVA).Through optimization,the optimal parameters were achieved for the required clad with a width-to-height ratio of 5:1.A high-speed camera was used to investigate the cladding process under various process parameters.The laser power positively affected the widths of the molten pool and cladding layer.The molten pool and clad heights decreased with increases in laser power and scanning speed.Fine acicular martensite grains in the colony and basket-weave distributions were predominant in the cross-section of the cladding layer.The macrostructure investigation showed that the widths of columnar prior-β grains decreased with the increase in laser scanning speed. 展开更多
关键词 Wire-feed laser cladding Geometry characteristics Ti-6Al-4V Cladding process Regression analysis Macrostructure and microstructure
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Impact of titanium on solidification behavior and macrostructure of 347H stainless steel 认领 引用
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作者 Shang-Yan Jiang Yu-Xin Zhou +3 位作者 Hui-Gai Li Jian-Ping Liang Jie Li Qi-Jie Zhai 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2026年第1期66-77,共12页
The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation... The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation of Ti-containing inclusions,enhancing heterogeneous nucleation and promoting equiaxed dendritic growth in 347H stainless steel.Thermal simulation experiments indicated that the equiaxed crystal ratios increased notably with Ti content;samples with 0.06,0.12,and 0.36 wt.%Ti exhibited equiaxed ratios of 18%,24%,and 41%,respectively.Three primary inclusion types—TiN,Al2O3-TiN,and TiOx-TiN—were identified at the cores of equiaxed dendrites,with nucleation core sizes predominantly ranging from 0.5 to 8μm.Among the tested samples,the 0.36 wt.%Ti addition produced the highest nucleation core density.Increasing Ti content significantly elevated dendrite tip undercooling from 2.6 K(0.06 wt.%Ti)to 10.8 K(0.36 wt.%Ti),accelerating solidification front instability and thus enhancing heterogeneous nucleation.Additionally,higher Ti content increased the divergence angle between adjacent columnar dendrites,further promoting the columnar-to-equiaxed transition(CET). 展开更多
关键词 347H stainless steel Continuous casting Solidification Macrostructure Inclusion Columnar-to-equiaxed transition Heterogeneous nucleation
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Templated synthesis of Ti02 nanotube macrostructures and their photocatalytic properties 认领 引用 被引量：9
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作者 Hongbian Li Qiaoyu Zhou +7 位作者 Yuntian Gao Xuchun Gui Long Yang Mingde Du Enzheng Shi Jidong Shi Anyuan Cao Ying Fang 《Nano Research》 SCIE CSCD 2015年第3期900-906,共7页
Controlled synthesis of hierarchically assembled titanium dioxide （TiO2） nano- structures is important for practical applications in environmental purification and solar energy conversion. We present here the fabric... Controlled synthesis of hierarchically assembled titanium dioxide （TiO2） nano- structures is important for practical applications in environmental purification and solar energy conversion. We present here the fabrication of interconnected TiO2 nanotubes as a macroscopic bulk material by using a porous carbon nanotube （CNT） sponge as a template. The basic idea is to uniformly coat an amorphous titania layer onto the CNT surface by the infiltration of a TiO2 precursor into the sponge followed by a subsequent hydrolysis process. After calcination, the CNTs are completely removed and the titania is simultaneously crystallized, which results in a porous macrostructure composed of interconnected anatase TiO2 nanotubes. The TiO2 nanotube macrostructures show comparable photocatalytic activities to commercial products （AEROXIDE TiO2 P25） for the degradation of rhodamine B （RhB）. Moreover, the TiO2 nanotube macrostructures can be settled and separated from water within 12 h after photocatalysis, whereas P25 remains suspended in solution after weeks. Thus the TiO2 nanotube macrostructures offer the advantage of easy catalyst separation and recycle and can be a promising candidate for wastewater treatment. 展开更多
关键词 TiO2 nanotube macrostructure carbon nanotube sponge photocatalysis
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Carbon Nanotubes:from Nanoscale Building Blocks to Macrostructures 认领 引用
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作者 Bingqing Wei 《复旦学报（自然科学版）》 CAS 北大核心 2007年第5期
1 Results Carbon nanotubes (CNTs) have fascinating properties.In order to use these novel one-dimensional structures for applications such as in nano-electronic,nano-mechanical and electrochemical energy storage devic... 1 Results Carbon nanotubes (CNTs) have fascinating properties.In order to use these novel one-dimensional structures for applications such as in nano-electronic,nano-mechanical and electrochemical energy storage device and as structural elements in various composites,the structure of nanotubes needs to be tailored and various architectures and macroscale assembles have to be configured using nanotube building blocks.Nanotube macrostructures are macroscopically organized groups of CNTs,which are expecte... 展开更多
关键词 carbon nanotubes macrostructures building blocks energy storage synthesis
Improving Joint Features and Mechanical Properties of Pinless Fiction Stir Welding of Alcald 2A12-T4 Aluminum Alloy 认领 引用 被引量：10
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作者 Zhenlei Liu Hutao Cui +2 位作者 Shude Ji Minqiang Xu Xiangchen Meng 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2016年第12期1372-1377,共6页
As a new solid state welding,pinless friction stir welding（PFSW） can be used to join thin-wall structures.In this study,four new pinless tools with different groove distributions were designed and manufactured in or... As a new solid state welding,pinless friction stir welding（PFSW） can be used to join thin-wall structures.In this study,four new pinless tools with different groove distributions were designed and manufactured in order to enrich technological storage of PFSW and obtain sound joint with high quality of alclad 2A12-T4 alloy.The results show that the small-obliquity tool is detrimental to the transfer of plasticized materials,resulting in the formation of kissing bond defect.For the through-groove tool or the large-curvature tool,bigger flashes form on the joint surface and alclad layer is observed in the nugget zone（NZ）,deteriorating mechanical properties.Compared with the above-mentioned three tools,using the six-groove tool with rational curvature and obliquity can not only yield sound joint with small flashes and thickness reduction,but also prevent alclad from flowing into NZ,which has potential to weld thin alclad aluminum alloys.Meanwhile,the tensile strength and elongation of joint using the six-groove tool reach the maximum values of 362 MPa and 8.3%,up to 85.1% and 64% of BM. 展开更多
关键词 Pinless friction stir welding Groove distribution 2A12-T4 aluminum alloy Macrostructures Mechanical property
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Recent progress in bio-inspired macrostructure array materials with special wettability—from surface engineering to functional applications 认领 引用 被引量：19
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作者 Zhongxu Lian Jianhui Zhou +4 位作者 Wanfei Ren Faze Chen Jinkai Xu Yanling Tian Huadong Yu 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第1期208-256,共49页
Bio-inspired macrostructure array(MAA,size:submillimeter to millimeter scale)materials with special wettability(MAAMs-SW)have attracted significant research attention due to their outstanding performance in many appli... Bio-inspired macrostructure array(MAA,size:submillimeter to millimeter scale)materials with special wettability(MAAMs-SW)have attracted significant research attention due to their outstanding performance in many applications,including oil repellency,liquid/droplet manipulation,anti-icing,heat transfer,water collection,and oil–water separation.In this review,we focus on recent developments in the theory,design,fabrication,and application of bio-inspired MAAMs-SW.We first review the history of the basic theory of special wettability and discuss representative structures and corresponding functions of some biological surfaces,thus setting the stage for the design and fabrication of bio-inspired MAAMs-SW.We then summarize the fabrication methods of special wetting MAAs in terms of three categories:additive manufacturing,subtractive manufacturing,and formative manufacturing,as well as their diverse functional applications,providing insights into the development of these MAAMs-SW.Finally,the challenges and directions of future research on bio-inspired MAAMs-SW are briefy addressed.Worldwide efforts,progress,and breakthroughs from surface engineering to functional applications elaborated herein will promote the practical application of bio-inspired MAAMs-SW. 展开更多
关键词 macrostructure arrays superhydrophobic 3D printing laser droplet manipulation
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Macro-and Microstructure Evolution of 5CrNiMo Steel Ingots during Electroslag Remelting Process 认领 引用 被引量：11
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作者 Lei RAO Jian-hua ZHAO +2 位作者 Zhan-xi ZHAO Gang DING Mao-peng GENG 《Journal of Iron and Steel Research International》 SCIE CAS CSCD 2014年第7期644-652,共9页
A comprehensive mathematical model was established and used to simulate the macro and microstructure evolution during the production process of 5CrNiMo steel ingot by electroslag remelting （ESR） method. Along the in... A comprehensive mathematical model was established and used to simulate the macro and microstructure evolution during the production process of 5CrNiMo steel ingot by electroslag remelting （ESR） method. Along the ingot height, the macrostructure distribution characteristics changed from vertical, fine columnar grains to tilted, coarse columnar grains, and this transformation process occurred at the very beginning of ESR. In the cross section of the ingot, there were three grain morphology regions and two grain type transition regions from the outside to the center of the ingot. These regions were the fine columnar grain region, columnar competitive growth transition re gion, coarse columnar grain region, columnar to equiaxed grain transition （CET） region, and coarse equiaxed grain region. The influence of the remelting rate on the macrostructure and mlcrostructure was investigated using a series of experiments and simulations. The results showed that a low remelting rate could produce a small grain growth angle （GGA） ; the average secondary dendrite arm spacing （SDAS） firstly decreased and then increased as the remelting rate increased. An excessively high or low remelting rate can increase the GGA and average SDAS in ingots. Thus, the remelting rate should be controlled within a suitable range to reduce composition microsegregation and microshrinkage in the ingot to produce an ESR ingot with satisfactory hot forging performance. 展开更多
关键词 electroslag remelting macrostructure microstructure remelting rate secondary dendrite arm spacing
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Numerical simulation of temperature distribution and heat transfer during solidification of titanium alloy ingots in vacuum arc remelting process 认领 引用 被引量：17
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作者 杨治军 赵小花 +3 位作者 寇宏超 李金山 胡锐 周廉 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS 2010年第10期1957-1962,共6页
In order to get a better understanding of the vacuum consumable arc remelting(VAR) processes and thus to optimize them,a 3D finite element model was developed for the temperature fields and heat transfer of titanium a... In order to get a better understanding of the vacuum consumable arc remelting(VAR) processes and thus to optimize them,a 3D finite element model was developed for the temperature fields and heat transfer of titanium alloy ingots during VAR process.The results show that the temperature fields obtained by the simulation are well validated through the experiment results.The temperature distribution is different during the whole VAR process and the steady-state molten pool forms at 329 s for d100 mm × 180 mm ingots.At the initial stage of remelting,the heat dissipation of crucible bottom plays an important role in the whole heat dissipation system.At the middle of remelting,the crucible wall becomes a major heat dissipation way.The effect of cooling velocity on the solidification structure of ingots was investigated based on the temperature fields and the results can well explain the macrostructure of titanium alloy ingots. 展开更多
关键词 vacuum arc remelting（VAR） process titanium alloy ingot macrostructure temperature field heat transfer
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Simulation of stray grain formation in Ni-base single crystal turbine blades fabricated by HRS and LMC techniques 认领 引用 被引量：12
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作者 Ya-feng Li Lin Liu +4 位作者 Tai-wen Huang Miao Huo Jun-sheng He Jun Zhang Heng-zhi Fu 《China Foundry》 SCIE CAS 2017年第2期75-79,共5页
The simulation models of the thermal and macrostructural evolutions during directional solidification of Ni-base single crystal(SX) turbine blades under high rate solidification(HRS) and liquid metal cooling(LMC) have... The simulation models of the thermal and macrostructural evolutions during directional solidification of Ni-base single crystal(SX) turbine blades under high rate solidification(HRS) and liquid metal cooling(LMC) have been constructed using Pro CAST software, coupled with a 3D Cellular Automaton Finite Element(CAFE) model. The models were used to investigate the tendencies of stray grain(SG) formation in the platform region of turbine blades fabricated by HRS and LMC techniques. The results reveal that the LMC technique can prohibit SG formation by smoothing the concaved isotherm and in turn alleviating the undercooling in the platform ends to let the dendrites fill up the undercooled zone before SG nucleation. The simulation results agreed well with the experimental results, indicating that these models could be used to analyze the macrostructural evolution or to optimize process parameters to suppress SG formation. Using these models, the critical withdrawal rate for casting SX turbine blades without SG formation were determined to be around 75 μm·s-1 and 100 μm·s-1 for HRS and LMC respectively, suggesting that LMC can be used as an efficient technique in fabricating SX turbine blades without any SG defect formation. 展开更多
关键词 thermal profile macrostructural evolution simulation HRS LMC stray grain
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The control and optimization of macro/micro-structure of ion conductive membranes for energy conversion and storage 认领 引用 被引量：8
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作者 Xiaoming Yan Wenji Zheng +3 位作者 Xuehua Ruan Yu Pan Xuemei Wu Gaohong He 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第5期558-571,共14页
Ion conductive membranes(ICMs)are frequently used as separators for energy conversion and storage technologies of fuel cells,flow battery,and hydrogen pump,because of their good ion-selective conduction and low electr... Ion conductive membranes(ICMs)are frequently used as separators for energy conversion and storage technologies of fuel cells,flow battery,and hydrogen pump,because of their good ion-selective conduction and low electronic conductivity.Firstly,this feature article reviews the recent studies on the development of new nonfluorinated ICMs with low cost and their macro/micro-structure control.In general,these new nonfluorinated ICMs have lower conductivity than commercial perfluorinated ones,due to their poor ion transport channels.Increasing ion exchange capacity(IEC)would create more continuous hydrophilic channels,thus enhancing the conductivity.However,high IEC also expands the overall hydrophilic domains,weakens the interaction between polymer chains,enhances the mobility of polymer chains,and eventually induces larger swelling.The micro-scale expansion and macro-scale swelling of the ICMs with high IEC could be controlled by limiting the mobility of polymer chains.Based on this strategy,some ef ficient techniques have been developed,including covalent crosslinking,semi-interpenatrating polymer network,and blending.Secondly,this review introduces the optimization of macro/microstructure of both perfluorinated and nonfluorinated ICMs to improve the performance.Macro-scale multilayer composite is an ef ficient way to enhance the mechanical strength and the dimensional stability of the ICMs,and could also decrease the content of per fluorosulfonic acid resin in the membrane,thereby reducing the cost of the perfluorinated ICMs.Long side chain,multiple functionalization,small molecule inducing micro-phase separation,electrospun nano fiber,and organic–inorganic hybrid could construct more ef ficient ion transport channels,improving the ion conductivity of ICMs. 展开更多
关键词 Ion conductive membranes Macrostructure Microstructure Optimization
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Additive manufacturing of 18%nickel maraging steels:Defect,structure and mechanical properties:A review 认领 引用 被引量：10
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作者 Lulu Guo Lina Zhang +1 位作者 Joel Andersson Olanrewaju Ojo 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2022年第25期227-252,共26页
This paper reviews the latest research progress in the additive manufacturing(AM)process of 18%nickel maraging steels,which involves laser-based powder bed fusion(L-PBF),laser-based directed energy deposition(L-DED),a... This paper reviews the latest research progress in the additive manufacturing(AM)process of 18%nickel maraging steels,which involves laser-based powder bed fusion(L-PBF),laser-based directed energy deposition(L-DED),and wire arc additive manufacturing(WAAM).The emphasis is on the defects,structure,and mechanical properties of the additive manufactured 18%nickel maraging steels.At first,this article outlines the influences of the processing parameters of AM techniques on the defects formed in the fabricated parts,in terms of the L-PBF and WAAM.The macrostructure and microstructure characteristics of as-built and heat-treated 18%nickel maraging steel are then described in detail.Later,the mechanical properties of as-built and heat-treated 18%nickel maraging steel are assessed,such as their tensile,hardness,impact toughness,and fatigue performances.Finally,future directions for work on the AM of 18%nickel maraging steel are provided. 展开更多
关键词 Additive manufacturing 18%Nickel maraging steel Defects Macrostructure Microstructure Mechanical properties
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Macrostructure and properties of thin walled copper tubes prepared by the downward continuous unidirectional solidification method 认领 引用 被引量：3
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作者 Xi Shen Hong Zhang +3 位作者 Zi-dong Wang Hua-fen Lou Yi-ming Jia Ping-xia Hu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS 2010年第1期63-68,共6页
The macrostructure and properties of the thin walled copper tube prepared by the downward continuous unidirectional solidification （DCUS） method were studied. The result shows that the macrostructure is closely rela... The macrostructure and properties of the thin walled copper tube prepared by the downward continuous unidirectional solidification （DCUS） method were studied. The result shows that the macrostructure is closely related to the solid-liquid interface profile, which is influenced by the distance between the cooling water location and the solidification front. The mechanical properties of the thin walled copper tube prepared by the DCUS method are near those of the normal cast copper, and it has good relative density, electrical conductivity, and elongation, which are not greatly affected by casting speed. The thin walled copper tube prepared by the DCUS method also has good processing properties that can be taken to further drawing procedures directly without an intermediate process, and obtains good mechanical properties with the total processing rate of 89.8%. 展开更多
关键词 unidirectional solidification copper tube short process macrostructure mechanical properties
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Macrostructural and microstructural features of 1000 MPa grade TRIP steel joint by CO_2 laser welding 认领 引用 被引量：3
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作者 王文权 孙大千 姜春云 《China Welding》 EI CAS 2008年第2期1-7,共7页
Bead-on-plate CO2 laser welding of 1 000 MPa grade transformation induced plasticity （TRIP） steel was conducted under different welding powers, welding speeds and shield gases. The macrostructural and microstructura... Bead-on-plate CO2 laser welding of 1 000 MPa grade transformation induced plasticity （TRIP） steel was conducted under different welding powers, welding speeds and shield gases. The macrostructural and microstructural features of the welded joint were investigated. The increase of welding speed reduced the width of the weld bead and the porosities in the weld bead resulting from the different flow mode of melted metal in weld pool. The decrease of welding power or use of shield gas of helium also contributed to the reduction of porosity in the weld bead due to the alleviation of induced plasma formation, thus stabilizing the keyhole. The porosity formation intimately correlated with the evaporation of alloy element Mn in the base metal. The laser welded metal had same martensite microstructure as that of water-quenched base metal. The welding parameters which increased cooling rate all led to fine microstructures of the weld bead. 展开更多
关键词 CO2 laser welding transformation induced plasticity steel macrostructure microstructure
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Mechanical and metallurgical characterization of AA6061 friction stir welded joints using microhardness map 认领 引用 被引量：3
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作者 Iman HEJAZI Seyyed Ehsan MIRSALEHI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第9期2313-2319,共7页
The relationships between microhardness and microstructure, macrostructure and mechanical properties of friction stir welded joints AA6061-T913 were studied. Three equations were suggested to predict the grain size, u... The relationships between microhardness and microstructure, macrostructure and mechanical properties of friction stir welded joints AA6061-T913 were studied. Three equations were suggested to predict the grain size, ultimate tensile strength and yield strength from the hardness throughout the weld. Two-dimensional contour of grain size and three-dimensional maps of ultimate tensile and yield strengths were plotted according to the proposed equations. Also, the location of macroscopic zones was estimated based on hardness distribution. The modeling results were compared with the results obtained from microscopy and tensile tests. The modeling results show good agreement with the experimental findings, and the average differences between them for the ultimate tensile strength and yield strength were about 8% and 3%, respectively. 展开更多
关键词 AA6061 alloy friction stir welding microhardness macrostructure microstructure mechanical properties
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Control of equiaxed grains in a complicated Cu-Ni based alloy prepared by centrifugal casting 认领 引用
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作者 Luo Zongqiang Zhang Weiwen +1 位作者 Xin Baoliang Li Yuanyuan 《China Foundry》 SCIE CAS 2011年第1期141-144,共4页
A complicated Cu-Ni based alloy was developed to fabricate wear-resisting bush for high temperature application.The concern focuses on the control of equiaxed grains in the developed alloy ingot prepared by centrifuga... A complicated Cu-Ni based alloy was developed to fabricate wear-resisting bush for high temperature application.The concern focuses on the control of equiaxed grains in the developed alloy ingot prepared by centrifugal casting.The results show that the equiaxed grains are determined by the pouring temperature of the melt,the cooling rate and the rotation speed of the mold.With the decrease in pouring temperature,the fraction of the equiaxed grains in the transverse section of the ingot increases and the average length of columnar grain decreases.When the pouring temperature is confined below 1,250℃,complete equiaxed grains can be obtained.Based on the optimal centrifugal casting processing,the tensile strength of the developed alloy ingot with complete equiaxed grains reaches to 810 MPa and 435 MPa at room temperature and 500℃,respectively,which is 14% and 110% higher than that of common commercial QAl10-4-4 alloy.The wear rate of the developed alloy is 7.0 × 10-8 and 3.8 × 10-7 mm3?N-1?mm-1 at room temperature and 500℃,respectively,which is 5 times and 39 times lower than that of QAl10-4-4 alloy. 展开更多
关键词 copper-nickel based alloy centrifugal casting macrostructures
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EFFECT OF ROTATING MAGNETIC FIELD ONMACROSTRUCTURE OF A CENTRIFUGALCASTING Al-1%Cu ALLOY 认领 引用 被引量：1
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作者 W.X. Han, X.H. Qin, D.Z. Li and K. Yang 《Acta Metallurgica Sinica(English Letters)》 EI CAS 2000年第5期1087-1092,共6页
Rotating electromagnetic field is applied to the centrifugal casting, the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or backing magnetic field are both examined. It is shown that both kin... Rotating electromagnetic field is applied to the centrifugal casting, the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or backing magnetic field are both examined. It is shown that both kinds of electromagnetic filed can enforce the columnar-equiaxed transition, the driving one decrease the tendency of porosity occurring due to the increase in the bulk liquid pressure. Stirring with braking electromagnetic field produces the mixture of outer fine grains and inner coarse grains in the casting, this is analyzed to be contributed to the differences both in electric conductivity and density between the crystal and the melt, as well as skin effects. 展开更多
关键词 centrifugal casting rotating magnetic field macrostructure Al1%Cu alloy
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Hubble Tension 认领 引用 被引量：2
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2022年第2期392-401,共10页
The results of measurements of the Hubble constant H0, which characterizes the expansion rate of the universe, show that the values of H0 vary significantly depending on Methodology. The disagreement in the values of ... The results of measurements of the Hubble constant H0, which characterizes the expansion rate of the universe, show that the values of H0 vary significantly depending on Methodology. The disagreement in the values of H0 obtained by the various teams far exceeds the standard uncertainties provided with the values. This discrepancy is called the Hubble Tension. In this paper, we discuss Macrostructures of the World (Superclusters and Galaxies);explain their Origin and Evolution in frames of the developed Hypersphere World-Universe Model (WUM), which is an alternative to the prevailing Big Bang Model (BBM) [1];and provide the explanation of the Hubble Tension. The main difference between WUM and BBM is: Instead of the Infinite Homogeneous and Isotropic Universe around the Initial Singularity in BBM, in WUM, the 3D Finite Boundless World (a Hypersphere) presents a Patchwork Quilt of different Luminous Superclusters (103), which emerged in various places of the World at different Cosmological times. In WUM, the Medium of the World is Homogeneous and Isotropic. The distribution of Macroobjects in the World is spatially Inhomogeneous and Anisotropic and temporally Non-simultaneous. 展开更多
关键词 Macrostructures of the World Hubble Constant Spatially Inhomogeneous and Anisotropic Distribution of Macroobjects Hypersphere World-Universe Model Homogeneous and Isotropic Medium
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