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Strengthening mechanism of T8-aged Al-Cu-Li alloy with increased pre-deformation

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Transactions of Nonferrous Metals Society of China 2024年第10期34卷 3151-3169页

作者： San-xi DENG Jin-feng LI Li WANG Yue-yan CHEN Zheng-wu XIANG Peng-cheng MA Yong-lai CHEN Dan-yang LIU School of materials Science and Engineering Central South UniversityChangsha 410083China Southwest Aluminum(Group)Co. Ltd.Chongqing 401326China Aerospace Research Institute of materials and Processing Technology Beijing 100076China

The microstructure evolution and mechanical properties of a T8-aged Al-Cu-Li alloy with increased pre-deformation(0-15%) were investigated,revealing the microstructure-strength relationship and the intrinsic strengthening *** results show that increasing the pre-deformation levels remarkably improves the strength of the alloy but deteriorates its *** introduced by pre-deformation effectively suppress the formation of Guinier-Preston(GP) zones and provide more nucleation sites for T1 *** leads to more intensive and finer T1 precipitates in the samples with higher pre-deformation ***,the enhanced precipitation of T1 precipitates and inhibited formation of GP zones cause the decreases in number and sizes of θ′ *** quantitative descriptions of the strength contributions from different strengthening mechanisms reveal that strengthening contributions from T1 and θ′ precipitates decrease with increasing *** reduced diameters of T1 precipitates are primarily responsible for their weakened strengthening ***,the improved strength of the T8-aged Al-Cu-Li alloy is mainly attributed to the stronger strain hardening from the increased pre-deformation levels.

关键词： Al−Cu−Li alloy pre-deformation precipitation strength strengthening mechanism

Mechanical Properties and Thermal Shock Resistance of SrAl_(2)Si_(2)O_(8) Reinforced BN Ceramic Composites

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无机材料学报 2024年第10期39卷 1182-1188页

作者： WANG Bo CAI Delong ZHU Qishuai LI Daxin YANG Zhihua DUAN Xiaoming LI Yanan WANG Xuan JIA Dechang ZHOU Yu International Joint Laboratory of Advanced Nanomaterials of Heilongjiang Province College of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration materials School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China China Resources Cement Technology R&D Co. LtdGuangzhou 510000China The First Military Representative Office of the Army Equipment Department in Beijing Beijing 100072China The Fourth System Design Department Fourth AcademyChina Aerospace Science and Industry Corporation LimitedBeijing 100048China School of materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Hexagonal boron nitride(h-BN)ceramics have become exceptional materials for heat-resistant components in hypersonic vehicles,owing to their superior thermal stability and excellent dielectric ***,their densification during sintering still poses challenges for researchers,and their mechanical properties are rather *** this study,SrAl_(2)Si_(2)O_(8)(SAS),with low melting point and high strength,was introduced into the h-BN ceramics to facilitate the sintering and reinforce the strength and ***,BN-SAS ceramic composites were fabricated via hot press sintering using h-BN,SrCO_(3),Al_(2)O_(3),and SiO_(2) as raw materials,and effects of sintering pressure on their microstructure,mechanical property,and thermal property were *** thermal shock resistance of BN-SAS ceramic composites was *** show that phases of as-preparedBN-SAS ceramic composites are h-BN and h-SrAl_(2)Si_(2)O_(8).With the increase of sintering pressure,the composites’densities increase,and the mechanical properties shew a rising trend followed by a slight *** a sintering pressure of 20 MPa,their bending strength and fracture toughness are(138±4)MPa and(1.84±0.05)MPa·m^(1/2),*** sintered at 10 MPa exhibit a low coefficient of thermal expansion,with an average of 2.96×10^(-6) K^(-1) in the temperature range from 200 to 1200℃.The BN-SAS ceramic composites prepared at 20 MPa display higher thermal conductivity from 12.42 to 28.42 W·m^(-1)·K^(-1) within the temperature range from room temperature to 1000℃.Notably,BN-SAS composites exhibit remarkable thermal shock resistance,with residual bending strength peaking and subsequently declining sharply under a thermal shock temperature difference ranging from 600 to 1400℃.The maximum residual bending strength is recorded at a temperature difference of 800℃,with a residual strength retention rate of 101%.As the thermal shock temperature difference increase,the degree of oxida

关键词： BN matrix composite hot-press sintering mechanical property thermal shock resistance service reliability

Properties of Self-recoverable Mechanoluminescence Phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) and Its Information Encryption Application

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发光学报 2024年第9期45卷 1445-1455页

作者： ZHANG Ting WANG Zhijun WANG Dawei ZHAO Jinxin YANG Zhiping LI Panlai Hebei Key Laboratory of Optic-electronic Information and materials College of Physics Science&TechnologyHebei UniversityBaoding 071002China Hebei Key Laboratory of Semiconductor Lighting and Display Critical materials Hebei Ledphor Optoelectronics Technology Co.LTD.Baoding 071000China

A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were ***_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good *** mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment *** mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter *** encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption *** results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.

关键词： phosphor mechanoluminescence self-recoverable information encryption

Microenvironment and electronic state modulation of Pd nanoparticles within MOFs for enhancing low-temperature activity towards DCPD hydrogenation

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Chinese Journal of Catalysis 2024年第9期64卷 112-122页

作者： Zhiyuan Liu Changan Wang Ping Yang Wei Wang Hongyi Gao Guoqing An Siqi Liu Juan Chen Tingting Guo Xinmeng Xu Ge Wang Beijing Advanced Innovation Center for materials Genome Engineering Beijing Key Laboratory of Function Materials for Molecule&Structure ConstructionSchool of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China Shunde Innovation School University of Science and Technology BeijingShunde 528399GuangdongChina Sinopec Research Institute of Petroleum Processing Co. LtdSINOPECBeijing 100083China

Precise control of the local environment and electronic state of the guest is an important method of controlling catalytic activity and reaction *** this paper,guest Pd NPs were introduced into a series of host UiO-67 MOFs with different functional ligands and metal nodes,the microenvironment and local electronic structure of Pd is modulated by introducing bipyridine groups and changing metal nodes(Ce6O6 or Zr6O6).The bipyridine groups not only promoted the dispersion Pd NPs,but also facilitated electron transfer between Pd and UiO-67 MOFs through the formation of Pd-N *** with Zr6 clusters,the tunability and orbital hybridisation of the 4f electronic structure in the Ce6 clusters modulate the electronic structure of Pd through the construction of the Ce-O-Pd *** optimal catalyst Pd/UiO-67(Ce)-bpy presented excellent low-temperature activity towards dicyclopentadiene hydrogenation with a conversion of>99%and a selectivity of>99%(50℃,10 bar).The results show that the synergy of Ce-O-Pd and Pd-N promotes the formation of active Pdδ+,which not only enhances the adsorption of H2 and electron-rich C=C bonds,but also contributes to the reduction of proton migration distance and improves proton utilization *** results provide valuable insights for investigating the regulatory role of the host MOFs,the nature of host-guest interactions,and their correlation with catalytic performance.

关键词： Interface regulation Pdδ+ Microenvironment Electronic state Hydrogenation

Effect of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy

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Transactions of Nonferrous Metals Society of China 2024年第8期34卷 2415-2430页

作者： Xian-wen YANG Ling-ying YE Yong ZHANG Quan-shi CHENG School of materials Science and Engineering Central South UniversityChangsha 410083China Aerospace Precision Production Co. Ltd.Tianjin 300300China

The effects of interrupted aging on mechanical properties and corrosion resistance of 7A75 aluminum alloy extruded bar were investigated through various analyses,including electrical conductivity,mechanical properties,local corrosion properties,and slow strain rate tensile stress corrosion *** characterization techniques such as metallographic microscopy,scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were also *** results indicate that the tensile strength of the alloy produced by T6I6 aging is similar to that produced by T6I4 aging,and it even exceeds 700 ***,the yield strength increases by 52.7 MPa,reaching 654.8 MPa after T6I6 aging *** maximum depths of intergranular corrosion(IGC)and exfoliation corrosion(EXCO)decrease from 116.3 and 468.5μm to 89.5 and 324.3μm,*** stress corrosion factor also decreases from 2.1%to 1.6%.These findings suggest that the alloy treated with T6I6 aging exhibits both high strength and excellent stress corrosion cracking ***,when the alloy is treated with T6I4,T6I6 and T6I7 aging,the sizes of grain boundary precipitates(GBPs)are found to be 5.2,18.4,and 32.8 nm,*** sizes of matrix precipitates are 4.8,5.7 and 15.7 nm,*** atomic fractions of Zn in GBPs are 9.92 at.%,8.23 at.%and 6.87 at.%,respectively,while the atomic fractions of Mg are 12.66 at.%,8.43 at.%and 7.00 at.%,***,the atomic fractions of Cu are 1.83 at.%,2.47 at.%and 3.41 at.%,respectively.

关键词： 7A75 aluminum alloy interrupted aging aging precipitation behavior mechanical properties intergranular corrosion exfoliation corrosion stress corrosion cracking

Microstructural evolution and dynamic recrystallization mechanisms of additively manufactured TiAl alloy with heterogeneous microstructure during hot compression

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Transactions of Nonferrous Metals Society of China 2024年第10期34卷 3208-3220页

作者： Hui TAO Hui-zhong LI Jia-hui LI Li WANG Wei-wei HE Xiao-fen TAN Rui ZHOU Xiao-peng LIANG School of materials Science and Engineering Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Key Laboratory of Nonferrous Metal materials Science and Engineering Ministry of EducationCentral South UniversityChangsha 410083China Xi'an Sailong AM technologies Co. Ltd.Xi’an 710016China Department of materials Science and Engineering Hong Kong Institute for Advanced StudyCity University of Hong KongKowloon 999077Hong KongChina

Microstructural evolution and dynamic recrystallization(DRX)mechanisms of a Ti-48Al-2Cr-2Nb(at.%)alloy prepared by selective electron beam melting(SEBM)during hot deformation at 1150℃and 0.1 s^(-1)were investigated by hot compression tests,optical microscope(OM),scanning electron microscope(SEM),electron back-scattered diffraction(EBSD)and transmission electron microscope(TEM).The results show that the initial microstructure of the as-SEBMed alloy exhibits layers of coarseγgrains and fineγ+α_(2)+(α_(2)/γ)lamellar mixture grains alternately along the building *** the early stage of hot deformation,deformation twins tend to form within the coarse grains,facilitating subsequent deformation,and a small number of DRX grains appear in the fine-grained *** the increase of strain,extensive DRX grains are formed through different DRX mechanisms in both coarse and fine-grained regions,involving discontinuous dynamic recrystallization mechanism(DDRX)in the fine-grained regions and a coexistence of DDRX and continuous dynamic recrystallization(CDRX)in the coarsegrained regions.

关键词： TiAl alloy selective electron beam melting heterogeneous microstructure discontinuous dynamic recrystallization(DDRX) continuous dynamic recrystallization(CDRX)

Corrosion Resistance Enhancement of Pure Zirconium in Various Environments via Microstructure Tailoring

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稀有金属材料与工程 2024年第8期53卷 2109-2122页

作者： Xia Chaoqun Li Ke Cui Ziyao Song Tianshuo Wu Xinyu Liu Shuguang ZouXianrui Zhang Shiliang Yang Tai Li Qiang Tianjin Key Laboratory of materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin 300401China Industrial Technology Research Institute Hebei University of TechnologyTianjin 300401China Engineering Research Center for Electrophysical Apparatus and Application Technology Beijing Research Institute of Automation for Machinery Industry Co.LtdBeijing 100120China

The corrosion properties of pure zirconium(Zr)with different grain sizes in acid,alkali,and salt environments were *** microstructures of pure Zr were observed by optical microscope,X-ray diffractometer,and electron backscattered diffraction *** corrosion resistance of pure Zr was analyzed by electrochemical corrosion test and immersion *** show that pure Zr with grain size of 4–32μm can be obtained after annealing at 800°C for different durations,and the relationship between grain size and annealing duration is D^(3)−D_(0)^(3)=*** electrochemical corrosion and immersion corrosion test results show that the pure Zr with grain size of about 24μm(annealing at 800°C for 20 h)possesses the optimal corrosion resistance.

关键词： pure zirconium grain size various environments corrosion resistance

Highly Weak-light Sensitive and Dual-band Switchable Photodetector Based on CuI/Si Unilateral Heterojunction

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无机材料学报 2024年第9期39卷 1063-1069页

作者： YANG Jialin WANG Liangjun RUAN Siyuan JIANG Xiulin YANG Chang Key Laboratory of Polar materials and Devices(MOE) Shanghai Center of Brain-inspired Intelligent Materials and DevicesDepartment of ElectronicsEast China Normal UniversityShanghai 200241China Institute of Intelligent Flexible Mechatronics Jiangsu UniversityZhenjiang 212013China Cell R&D Center JA Solar Holdings Co.LtdYangzhou 225000China

In recent years,copper iodide(CuI)is an emerging p-type wide bandgap semiconductor with high intrinsic Hall mobility,high optical absorption and large exciton binding ***,the spectral response and the photoelectric conversion efficiency are limited for CuI-based heterostructure devices,which is related to the difficulty in fabrication of high-quality CuI thin films on other *** this study,a p-CuI/n-Si photodiode has been fabricated through a facile solid-phase iodination *** the CuI thin film is polycrystalline with obvious structural defects,the CuI/Si diode shows a high weak-light sensitivity and a high rectification ratio of 7.6×10^(4),indicating a good defect *** is because of the unilateral heterojunction behavior of the formation of the p^(+)n *** this work,the mechanism of photocurrent of the p^(+)n diode has been studied *** monochromatic lasers with wavelengths of 400,505,635 and 780 nm have been selected for testing the *** zero-bias voltage,the device is a unilateral heterojunction,and only visible light can be absorbed at the Si *** the other hand,when a bias voltage of-3 V is applied,the photodiode is switched to a broader“UV-visible”band response ***,the detection wavelength range can be switched between the“Visible”and“UV-visible”bands by adjusting the bias ***,the obtained CuI/Si diode was very sensitive to weak light illumination.A very high detectivity of 10^(13)-1014 Jones can be achieved with a power density as low as 0.5μW/cm^(2),which is significantly higher than that of other Cu-based *** findings underscore the high application potential of CuI when integrated with the traditional Si industry.

关键词： er iodide heterojunction photodetector

Irregular initial solidification by mold thermal monitoring in the continuous casting of steels:A review

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International Journal of Minerals,Metallurgy and materials 2024年第5期31卷 1003-1015页

作者： Qiuping Li Guanghua Wen Fuhang Chen Ping Tang Zibing Hou Xinyun Mo College of materials Science and Engineering Chongqing UniversityChongqing 400044China Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New materials Chongqing UniversityChongqing 400044China

Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of *** application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification *** systems are widely applied in numerous steel companies for sticker breakout ***,monitoring the surface defects of strands remains ***,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM *** paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM ***,the influences of mold slag behavior on monitoring these phenomena are ***,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.

关键词： irregular initial solidification mold thermal monitoring continuous casting mold slag thermocouple