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Effects of pre-aging on microstructure evolution and deformation mechanisms of hot extruded Mg–6Zn–1Gd–1Er Mg alloys 被引量:6
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作者 Wei Kang Liwei Lu +3 位作者 Longbiao Feng Fengchi Lu Chunlei Gan Xiaohui Li 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第1期317-328,共12页
The influence of pre-aging treatment on the microstructure,texture and mechanical properties of the Mg–6Zn–1Gd–1Er(wt.%)alloy was investigated.The microstructure analysis shows that the presence of pre-aging is ben... The influence of pre-aging treatment on the microstructure,texture and mechanical properties of the Mg–6Zn–1Gd–1Er(wt.%)alloy was investigated.The microstructure analysis shows that the presence of pre-aging is beneficial to{1012}twin nucleation at the early stage of extrusion and inhibits the growth of twins and promotes the formation of[1010]-fiber texture components,thus accelerating the complex process of recrystallization.In the middle stage of extrusion,the extruded samples under the condition of solid solution were subjected to dynamic precipitation during severe shear deformation.The precipitation of the second phase particles followed the particle stimulating nucleation(PSN)mechanism,which increased the volume fraction of DRX grains during extrusion.In the extruded samples under the peak-aged condition,the particles appear dissolved during the severe shear deformation strain,which slows down the DRX process.In the later stage of extrusion,the small rod-shaped particles followed the PSN mechanism,and finally formed the strong fiber texture.The extruded alloy exhibits the strongest mechanical properties under the peak-aged state,with ultimate tensile strength(UTS)of 346 MPa,tensile yield strength(TYS)of 217 MPa,and elongation to failure(EL)of 13.6%.The improvement of mechanical properties is mainly attributed to the existence of strong fiber texture,small rod-shaped and block-shaped phases. 展开更多
关键词 Mg alloys PRE-AGING EXTRUSION TEXTURE Dynamic recrystallization
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Flow curve correction and processing map of 2050 Al-Li alloy 被引量:6
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作者 Rui-hua ZHU Qing LIU +3 位作者 Jin-feng LI Yong-lai CHEN Xu-hu ZHANG Zi-qiao ZHENG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第3期404-414,共11页
Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effect... Hot compression tests of 2050 Al-Li alloy were performed in the deformation temperature range of 340-500°C and strain rate range of 0.001-10 s-1 to investigate the hot deformation behavior of the alloy.The effects of friction and temperature difference on flow stress were analyzed and the flow curves were corrected.Based on the dynamic material model,processing map at a strain of 0.5 was established.The grain structure of the compressed samples was observed using optical microscopy.The results show that friction and temperature variation during the hot compression have significant influences on flow stress.The optimum processing domains are in the temperature range from 370 to 430°C with the strain rate range from 0.01 to 0.001 s-1,and in the temperature range from 440 to 500°C with the strain rate range from 0.3 to 0.01 s-1;the flow instable region is located at high strain rates(3-10 s-1)in the entire temperature range.Dynamic recovery(DRV)and dynamic recrystallization(DRX)are the main deformation mechanisms of the 2050 alloy in the stable domains,whereas the alloy exhibits flow localization in the instable region. 展开更多
关键词 2050 Al-Li alloy processing map dynamic recovery dynamic recrystallization flow localization
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Effect of pre-deformation on microstructure and mechanical properties of WE43 magnesium alloy II: Aging at 250 and 300℃ 被引量:20
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作者 Y.H.Kang Z.H.Huang +3 位作者 S.C.Wang H.Yan R.S.Chen J.C.Huang 《Journal of Magnesium and Alloys》 SCIE 2020年第1期103-110,共8页
In this work,the microstructural evolution and mechanical properties of a pre-deformed WE43 magnesium alloy when aged at 250 and 300℃ were further investigated.It is found that the abundant deformation twins introduc... In this work,the microstructural evolution and mechanical properties of a pre-deformed WE43 magnesium alloy when aged at 250 and 300℃ were further investigated.It is found that the abundant deformation twins introduced by pre-deformation were maintained within the alloy during the aging treatment.Second particles formed at the twin boundaries and coarsened with aging time,especially at 300℃.When peak-aged at 250℃,the fine metastable β'''and β' precipitates formed in the un-deformed alloy have been transformed into relatively large β1 and β precipitates by the pre-deformation.While peak-aged at 300℃,the pre-deformation obviously refined the β precipitates.Mechanical properties indicate that pre-deformation can increase the yield strength by 19MPa and 54MPa for the peak-aged alloy at 250℃ and 300℃,respectively,and will not obviously deteriorate the tensile elongations. 展开更多
关键词 WE43 magnesium alloy PRE-DEFORMATION AGING MICROSTRUCTURE Mechanical properties
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Microstructures and properties of Al_2O_3 dispersion-strengthened copper alloys prepared through different methods 被引量:5
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作者 Zhi-qiao Yan Feng Chen +2 位作者 Fu-xing Ye Dong-ping Zhang Yi-xiang Cai 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第12期1437-1443,共7页
Al2O3 dispersion copper alloy powder was prepared by intemal oxidation, and three consolidation methods--high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)--were used to prepare Al2O3 disp... Al2O3 dispersion copper alloy powder was prepared by intemal oxidation, and three consolidation methods--high-velocity compaction (HVC), hot pressing (HP), and hot extrusion (HE)--were used to prepare Al2O3 dispersion-strengthened copper (Cu-Al2O3) alloys. The microstructures and properties of these alloys were investigated and compared. The results show that the alloys prepared by the HP and HE methods exhibited the coarsest and finest grain sizes, respectively. The alloy prepared by the HVC method exhibited the lowest relative density (98.3% vs. 99.5% for HP and 100% for HE), which resulted in the lowest electrical conductivity (81% IACS vs. 86% IACS for HP and 87% IACS for HE). However, this alloy also exhibited the highest hardness (77 HRB vs. 69 HRB for HP and 70 HRB for HE), the highest compressive strength (443 MPa vs. 386 MPa for I/P and 378 MPa for HE), and the best hardness retention among the investigated alloys. The results illustrate that the alloy prepared by the HVC method exhibits high softening temperature and good mechanical properties at high temperatures, which imply long service life when used as spot-welding electrodes. 展开更多
关键词 dispersion-strengthened alloys copper alloys ALUMINA preparation methods microstructure properties
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Effect of melt holding on morphological evolution and sedimentation behavior of iron-rich intermetallic phases in Al-Si-Fe-Mn-Mg alloy 被引量:7
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作者 Dong-fu SONG Shun-cheng WANG +5 位作者 Yu-liang ZHAO Shu-hong LIU Yong DU Yue-hua KANG Zhi WANG Wei-wen ZHANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第1期1-13,共13页
The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,sc... The effect of the melt holding temperature on the morphological evolution and sedimentation behavior of iron-rich intermetallics in Al-7.0 Si-1.0 Fe-1.2 Mn-0.25 Mg alloy was investigated using an optical microscope,scanning electron microscope and differential thermal analyzer.The results show that as the holding temperature decreases,the morphologies of the primary iron-rich phase in matrix change from star-like to polygonal,and the number of the primary phases gradually decreases and disappears at 615°C.Finally,the Chinese script phases with small size,high compact and uniform distribution are obtained.In contrast,the primary iron-rich phases in slag transform into a coarser polygonal shape with lower roundness,and some of them have hollow structures.Furthermore,the area fraction of intermetallics and Fe content in the matrix decrease gradually due to the formation and growth of sludge and subsequent natural sedimentation during melt holding.With the decrease of holding temperature,the main factors hindering the settlement of the primary phases are morphology,size,and density in turn. 展开更多
关键词 Al-Si alloy melt holding iron-rich intermetallic phases morphological evolution sedimentation behaviour
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Microstructure and properties of 7A52 Al alloy welded joint 被引量:9
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作者 黄继武 尹志民 雷学锋 《中国有色金属学会会刊:英文版》 CSCD 2008年第4期804-808,共5页
7A52 Al alloy plate aged at 105 ℃ for 8 h and then at 130 ℃ for 24 h was welded by means of TIG using Al- 6.3Mg-0.35Sc-0.1Zr-0.1Cr solder wire. Mechanical properties and microstructures of welded joint were studied.... 7A52 Al alloy plate aged at 105 ℃ for 8 h and then at 130 ℃ for 24 h was welded by means of TIG using Al- 6.3Mg-0.35Sc-0.1Zr-0.1Cr solder wire. Mechanical properties and microstructures of welded joint were studied. There are two obviously soft areas in the welded joint, welding seam and over-aging zone. The mechanical properties of welded joint are that σb is 358 MPa, σ0.2 is 238 MPa and δ5 is 6.6%. 75.6% of welding coefficient can be achieved. The addition of scandium leads to very significant grain refinement in the fusion zone, which results in a reduction in solidification cracking tendency. The solidification cracking isn’t observed. 展开更多
关键词 微合金 铝合金 焊接节点 微观结构 力学性能
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Design and calculation of low infrared transmittance and low emissivity coatings for heat radiative applications 被引量:4
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作者 Cruang-hai Wang Yue Zhang +1 位作者 Da-hai Zhang Jin-peng Fan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2012年第2期179-184,共6页
The infrared transmittance and emissivity of heat-insulating coatings pigmented with various structural particles were studied using Kubelka-Munk theory and Mie theory. The primary design purpose was to obtain the low... The infrared transmittance and emissivity of heat-insulating coatings pigmented with various structural particles were studied using Kubelka-Munk theory and Mie theory. The primary design purpose was to obtain the low transmittance and low emissivity coatings to reduce the heat transfer by thermal radiation for high-temperature applications. In the case of silica coating layers constituted with various structural titania particles (solid, hollow, and core-shell spherical), the dependence of transmittance and emissivity of the coating layer on the particle structure and the layer thickness was investigated and optimized. The results indicate that the coating pigmented with core-shell titania particles exhibits a lower infrared transmittance and a lower emissivity value than that with other structural particles and is suitable to radiative heat-insulating applications. 展开更多
关键词 scattering PIGMENTS COATINGS TRANSMITTANCE EMISSIVITY
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Microstructure, Texture, and Hardness Evolutions of Al-Mg-Si-Cu Alloy during Annealing Treatment 被引量:3
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作者 WANG Xiaofeng MA Cunqian +2 位作者 MA Pengcheng ZHOU Songze WANG Yonggang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2019年第6期1288-1296,共9页
Microstructure, texture and hardness evolutions of Al-Mg-Si-Cu alloy during annealing treatment were studied by microstructure, texture and hardness characterization in the present study. The experimental results show... Microstructure, texture and hardness evolutions of Al-Mg-Si-Cu alloy during annealing treatment were studied by microstructure, texture and hardness characterization in the present study. The experimental results show that microstructure, texture and hardness will change to some extent with the increase of annealing temperature. The microstructure transforms from the elongated bands to elongated grains first, and then the grains grow continuously. The texture transforms from the initial deformation texture b fiber to recrystallization texture mainly consisting of CubeND {001}<310> and P {011}<122> orientations first, and then the recrystallization texture may be enhanced continuously as a result of the grain growth. Hardness decreases slowly at first, and then decreases sharply and increases significantly finally. Besides, the particle distributions also have great changes. As the annealing temperature increases, they increase firstly as a result of precipitation, and then gradually disappear as a result of dissolution. Finally, the effect of annealing temperature on microstructure, texture and hardness evolutions is discussed. 展开更多
关键词 Al-Mg-Si-Cu alloy HARDNESS MICROSTRUCTURE TEXTURE RECRYSTALLIZATION
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Effect of Ti and Al on microstructure and partitioning behavior of alloying elements in Ni-based powder metallurgy superalloys 被引量:2
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作者 Yin-long Shao Jing Xu +8 位作者 Hao Wang Yi-wen Zhang Jian Jia Jian-tao Liu Hai-liang Huang Ming Zhang Zhi-cheng Wang Hong-fei Zhang Ben-fu Hu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2019年第4期500-506,共7页
The microstructure and partitioning behaviors of alloying elements in the γ and γ′ phases in Ni-based powder metallurgy superalloys with different Ti and Al contents were investigated. The results showed that Ti an... The microstructure and partitioning behaviors of alloying elements in the γ and γ′ phases in Ni-based powder metallurgy superalloys with different Ti and Al contents were investigated. The results showed that Ti and Al were mainly enriched in the γ′ phase, partially partitioned in the γ matrix, and slightly distributed in the carbides. Different Ti and Al contents in various alloys influenced the composition and amount of MC carbides but did not influence the MC carbides' morphology. With increasing Ti and Al contents, γ + γ′ fan-type structures formed at the grain boundary, eventually resulting in a coarsened γ′ phase. In addition, the morphology of the secondary γ′ phase transformed from nearly spherical to cuboidal. The saturation degrees of Cr, Co, and Mo in the γ matrix were substantially improved with increasing Ti and Al contents. 展开更多
关键词 SUPERALLOY AL TI MICROSTRUCTURE partitioning
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Metallurgical modeling of microcrack repairment during welding nonferrous materials: non-equilibrium solidification behavior of weld pool (Ⅰ) 被引量:2
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作者 Gao Zhiguo 《China Welding》 EI CAS 2017年第2期32-42,共11页
Metallurgical modeling of synergistic microcrack self-repairmen during welding single crystal and polycrystalline superalloys of high-temperature aerospace materials has been properly established. The idea of improvem... Metallurgical modeling of synergistic microcrack self-repairmen during welding single crystal and polycrystalline superalloys of high-temperature aerospace materials has been properly established. The idea of improvement of nickel-based superalloys weldability through non-equilibrium solidification behavior of backfill to self-repair arterial crack network is usefully proposed. Crystallographic control strategy of crack self-repairmen of fusion zone interdendritic solidification cracking and heat-affected zone (HAZ) intergranular liquation cracking is technically achievable, indicating that optimal niobium alloying beneficially refines weld microstructure, stabilizes the primary solidification path, increases the solidification temperature and concomitantly decreases the weld pool geometry. High-carbon grain boundary is more thermal stable and less contributes to incipient intergranular liquid film than that of low-carbon grain boundary. The theoretical predictions of cracking susceptibility are indirectly verified in a rather satisfactory manner. Additionally, the metallurgical modeling enhances predicative capabilities and thereby is readily applicable for other alloy systems. 展开更多
关键词 metallurgical modeling nickel alloys solidification behavior cracking repairmen
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Metallurgical modeling of microcrack repairment during welding nonferrous materials: non-equilibrium grain boundary segregation(Ⅱ) 被引量:1
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作者 Gao Zhiguo 《China Welding》 EI CAS 2017年第3期39-50,共12页
Metallurgical modeling of microalloying boron behavior in nickel-based superalloys during pre-weld heat treatment and welding has been systematically established. Non-equilibrium grain boundary resegregation is physic... Metallurgical modeling of microalloying boron behavior in nickel-based superalloys during pre-weld heat treatment and welding has been systematically established. Non-equilibrium grain boundary resegregation is physically coupled with non-equilibrium solidification of the weld pool for improved quantitative understanding of the imminent detriment of boron near the as-transformed grain boundary of the mushy zone and weldability. A strategic priority of the reduction in boron through low heat input and pre-weld heat treatment to suppress massive boride nucleation and grain boundary liquation are introduced.Both factors are capable of reducing the material response to boron-assisted intergranular liquation cracking at the high-energy sites of the grain-coarsened heat-affected zone( HAZ) beneath the surface and are of practical importance to provide robust integrity of joints. The synergistic self-repairment arterial crack network with the crystallographic substructure of the backfill enables amelioration of the HAZ crack resistance. The theoretical predictions are in satisfactory agreement with the phenomenological microanalysis, indirectly. This metallurgical modeling is also applicable to other high-temperature aerospace materials with similar metallurgical properties. 展开更多
关键词 BORON SEGREGATION solution heat treatment WELDABILITY INTERGRANULAR CRACKING
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A New Method for Detecting Internal Defects in Composite Materials Based on Time of Flight 被引量:1
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作者 ZHI Fan ZHANG Ying +2 位作者 SUN Jianbo LUO Ming LU Wu 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2022年第3期314-325,共12页
Carbon-fiber reinforced polymer composites have been widely used to achieve the light-weighted design and high performance due to superior performance. Internal defects in the composite materials are the main factors ... Carbon-fiber reinforced polymer composites have been widely used to achieve the light-weighted design and high performance due to superior performance. Internal defects in the composite materials are the main factors that determine their performance,which makes reliable and effective detection methods of internal defects essential. Nondestructive testing(NDT)methods are the most widely-used way due to their tremendous advantages. Though the theoretical background is found,experimental results could be quite complicated and confusing,especially for composite materials with complex defects characteristics. In this paper,experimental study on internal defects in composite materials based on the time of flight(ToF)are investigated. The Gaussian echo model and the parameter estimation methods are established to build a theoretical model for measurements. Then,the distance amplitude correction(DAC)method is proposed to effectively improve the signal-to-noise ratio(SNR)and to reduce distortion of the signal during measurements. Finally,the ToF is adopted to determine depth of internal defects. Experiment study is conducted to investigate the porosity defects and the anti-impact performance of composite materials,as well as defects in objects with various thicknesses. Experimental results show that the proposed method is quite helpful for obtaining the intuition and deep understanding of internal defects,thus contributing to the determination of product performance and its improvement. 展开更多
关键词 ultrasonic non-destructive testing time of flight porosity defects anti-impact performance distance amplitude correction(DAC)method
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Hot deformation behavior of Al-Cu-Li-Mg-Zr alloy containing Zn and Mn 被引量:1
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作者 陈永来 李劲风 +4 位作者 吕宏军 李世晨 郑子樵 张宇伟 张绪虎 《中国有色金属学会会刊:英文版》 CSCD 2007年第A01期271-275,共5页
The hot deformation behavior of a new Al-Cu-Li-Mg-Zr alloy was studied,and its microstructure and true stress were characterized as function of the deformation temperature and the strain rate using Gleeble-1500 therma... The hot deformation behavior of a new Al-Cu-Li-Mg-Zr alloy was studied,and its microstructure and true stress were characterized as function of the deformation temperature and the strain rate using Gleeble-1500 thermal mechanical simulator. The results show that,with the increase of the strain rate from 0.001 s-1 to 10 s-1,the peak value of true stress is elevated at the same deformation temperature,and at the same strain rate the peak value of the true stress decreases with the increase of the deformation temperature from 360 ℃ to 520 ℃. Dynamic recrystallization easily occurs in the new Al-Cu-Li-Mg-Zr alloy under the lower strain rate and the higher deformation temperature,and dynamic recovery can usually be seen in this alloy under the higher strain rate of 10 s-1 and the lower deformation temperature. 展开更多
关键词 合金 热成型技术 压力 流体
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HIP diffusion bonding of P/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti 被引量:1
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作者 郎泽保 王亮 张绪虎 《中国有色金属学会会刊:英文版》 CSCD 2007年第A01期79-83,共5页
The HIP diffusion bonding of P/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti using pure Ni as intermediate layer was studied. Bonding joint with complex bonding interface was obtained by HIPing pre-alloyed... The HIP diffusion bonding of P/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti using pure Ni as intermediate layer was studied. Bonding joint with complex bonding interface was obtained by HIPing pre-alloyed Ti-6Al-4V powders and stainless steel 1Cr18Ni9Ti in a vacuum canning. The joint strengths were examined and the characteristics of bonding joint were observed. The result shows that the maximized strength of HIP diffusion bonding between P/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti can be up to 388 MPa and the microstructure of bonding joint is acceptable. 展开更多
关键词 合金 连接强度 不锈钢
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Superplasticity and Superplastic Bulging Behavior of ZrO_2/Ni Nanocomposite
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作者 丁水 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第1期56-60,共5页
ZrO2/Ni nanocomposite was produced by pulse electrodeposition and its superplastic properties were investigated by the tensile and bulging tests. The as-deposited nickel matrix has a narrow grain size distribution wit... ZrO2/Ni nanocomposite was produced by pulse electrodeposition and its superplastic properties were investigated by the tensile and bulging tests. The as-deposited nickel matrix has a narrow grain size distribution with a mean grain size of 45 nm. A maximum elongation of 605% was observed at 723 K and a strain rate of 1.67×10-3s-1 by tensile test. Superplastic bulging tests were subsequently performed using dies with diameters of 1 mm and 5 mm respectively based on the optimal superplastic forming temperature. The effects of forming temperature and gas pressure on bulging process were experimentally investigated. The results indicated that ZrO2/Ni nanocomposite samples can be readily bulged at 723 K with H/d value (defined as dome apex height over the die diameter) larger than 0.5, indicating that the nanocomposite has good bulging ability. SEM and TEM were used to examine the microstructure of the as-deposited and bulged samples. The observations showed that significant grain coarsening occurs during superplastic bulging, and the microstructure is found to depend on the forming temperature. 展开更多
关键词 SUPERPLASTICITY BULGING MICROSTRUCTURE ZrO2/Ni nanocomposite
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High-temperature diffusion behavior of ZrC in C matrix and its promotion on graphitization
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作者 Zhong-wei ZHANG Qiang ZHEN +4 位作者 Feng ZHENG Fei LU Ce-wen NAN Rong LI Jun-shan WANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第8期2257-2262,共6页
C/C composite material is widely used in aerospace field and others, however, it is easy to be oxidized at high temperature.In order to improve the oxidation resistance, ZrC is introduced as an oxidation inhibitor use... C/C composite material is widely used in aerospace field and others, however, it is easy to be oxidized at high temperature.In order to improve the oxidation resistance, ZrC is introduced as an oxidation inhibitor used in matrix modification of C/C composite material. Flat plate samples of ZrC/C composite materials were prepared by hot-pressing sintering. The degree of graphitization increases with rising sintering temperature, and layer structure of carbon matrix is observed clearly in the sample treated at 2273 K. Diffusion behavior of Zr in C matrix at high temperature is studied, which can be generally expressed as D=3.382×10?11 exp[2.029×105/(RT)]. The diffusion of Zr in C matrix leads to the over-saturation of C in the micro area and the oversaturated C precipitates as graphite. This continuous process promotes the transformation of carbon to graphite. 展开更多
关键词 ZRC carbon material DIFFUSION GRAPHITIZATION
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Simulation on Pyrolysis Products of Thermoset Phenolic Resin with Different Chemical Structure and Experimental Validation
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作者 Honglin Hu Lu Zhang +5 位作者 Liang Liu Liqin Jiang Na Huang Zhiyu Chen Ruilian Yu Zhizhong Meng 《材料科学与工程(中英文A版)》 2019年第4期162-168,共7页
The simulation on pyrolysis products of pure PF resin with different chemical structure was investigated and validated by pyrolysis gas-chromatography mass spectrometry(Py-GC/MS).The simulation of pyrolysis products o... The simulation on pyrolysis products of pure PF resin with different chemical structure was investigated and validated by pyrolysis gas-chromatography mass spectrometry(Py-GC/MS).The simulation of pyrolysis products of phenolic resin with different chemical structure was investigated by AMBER(Assisted Model Building with Energy Refinement)force field.The content of pyrolysis products phenol and cresol decreases with the increase of F/P(formaldehyde/phenol)value.The content of pyrolysis products dimethylphenol and trimethylphenol increases with the enhancement of F/P value.The crosslink density of phenolic mixture can be measured by the content of pyrolysis products dimethylphenol and trimethylphenol.Consequently,the results of simulation were validated by the Py-GC/MS experiment. 展开更多
关键词 SIMULATION pyrolysis products phenolic resin crosslink density
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Effect of Deposition Time on Microstructures and Growth Behavior of ZrC Coatings Prepared by Low Pressure Chemical Vapor Deposition with the Br2-Zr-C3H6-H2-Ar System
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作者 马新 LI Yong +4 位作者 MEI Min 胡海峰 HE Xinbo QU Xuanhui CHEN Si'an 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第2期284-288,共5页
ZrC coatings were deposited on graphite substrates by low pressure chemical vapor deposition(LPCVD) with the Br2-Zr-C3H6-H2-Ar system. The effects of deposition time on the microstructures and growth behavior of ZrC... ZrC coatings were deposited on graphite substrates by low pressure chemical vapor deposition(LPCVD) with the Br2-Zr-C3H6-H2-Ar system. The effects of deposition time on the microstructures and growth behavior of ZrC coatings were investigated. ZrC coating grew in an island-layer mode. The formation of coating was dominated by the nucleation of ZrC in the initial 20 minutes, and the rapid nucleation generated a fine-grained structure of ZrC coating. When the deposition time was over 30 min, the growth of coating was dominated by that of crystals, giving a column-arranged structure. Energy dispersive X-ray spectroscopy showed that the molar ratio of carbon to zirconium was near 1:1 in ZrC coating, and X-ray photoelectron spectroscopy showed that ZrC was the main phase in coatings, accompanied by about 2.5mol% ZrO2 minor phase. 展开更多
关键词 ZrC ultra-high temperature ceramic microstructures growth behaviors chemical vapor deposition
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Observation and verification of surface electrical explosion driven by radial-distributed pulsed current in laboratory lightning strike test
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作者 Ruoyu Han Yuchen Cao +4 位作者 Yakun Liu Xi Chen Ting Li Chen Li Pengfei Li 《High Voltage》 SCIE EI CSCD 2024年第1期137-149,共13页
The laboratory lightning test is essential for assessing the effectiveness of lightning strike protection(LSP).Particularly,direct lightning strike damage can be performed with pulsed current injection into the specim... The laboratory lightning test is essential for assessing the effectiveness of lightning strike protection(LSP).Particularly,direct lightning strike damage can be performed with pulsed current injection into the specimen.This paper focuses on the dynamic process of arc plasma and shock wave behaviour in the vicinity of the‘strike’point.A rod-plate discharge load is built for testing aluminium and coated plate under 40-kA-level pulsed current.The visualisation of the luminous discharge plasma and its flow field via high-speed photography(from different angles)is meticulously designed and implemented,synchronised with electro-physical diagnostics.The results indicate some new mechanisms for lightning strike damage,apart from the impulse heat loading from the thermal arc.The transient current injection through the arc root concentrates on a thin skin layer(skin-depth effect),with the radial-attenuated current density,driving asynchronously electrical explosions on the plate surface.The inhomogeneous Joule heating of the plate leads to outwardly propagating phase transition and shock wave along the conductive surface.In addition,the electro-thermal instability is observed and regarded as the seed of irregular erosion region.Spectroscopic information reveals two different plasma states of main discharge arc channel and adjacent surface electrical explosion.The correspondence of the physical mechanism of electrical explosion and optical radiation is established.Microscopic images for different regions depict erosion characteristics and summarise influencing factors,further confirming the mechanism above.The research clarifies the role of skin-depth effect in transaction arc erosion for electrode,complements the electrical explosion theory with unevenly distributed current and helps optimise strategies of LSP. 展开更多
关键词 electrical LIGHTNING RADIAL
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Matching Performance among Visible and near Infrared Coating,Low Infrared Emitting Coating and Microwave Absorbing Coating 被引量:11
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作者 谢国华 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2005年第4期55-59,共5页
The matching performance among the visible and near infrared coating.the low infrared emitting coating and the microwave absorbing coating was investigated.Experimental results show that the resulting malerial is char... The matching performance among the visible and near infrared coating.the low infrared emitting coating and the microwave absorbing coating was investigated.Experimental results show that the resulting malerial is characteristic of wideband effect ranging from the visible,near infrared and 3-5μm,8-14μm infrared protion of the spectrum,as well as the radar region from 8 to 18GHz when these three materials form αlayerstructure material system.The microwave absorbing ability of material is hardly changed.The resonance peak moves towards lower frequency as the thickness of the visible,near infrared coating and the low infrared emitting coating increases.This problem can be resolved by controlling the thickness of the matrial.On the other hand, the infrared emissivity εof the material system increases as the thickness of the visible,near infrared coating increases.This can be resolved by increasing infrared transparency of the visible and near infrared topcoating or controlling its thickness.The experimental resulting material system has spectral reflection characteristics in visible and near infrared regions that are similar to those of the natural background. 展开更多
关键词 VISIBLE near infrared INFRARED MICROWAVE camouflage coating
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