检索结果-南通市图书馆

Dislocation density-me diate d creep ageing behavior of an Al-Cu-Li alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第7期174卷 204-217页

作者： Chang Zhou Lihua Zhan Chunhui Liu minghui huang College of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of Precision Manufacturing for Extreme Service Performance Central South UniversityChangsha 410083China Light Alloys Research Institute Central South UniversityChangsha 410083China

Creep aging is well-known to be a time-dependent,coupled process of deformation and precipitation strengthening for age-hardening *** existing mechanisms are mainly attributed to those interac-tions between atomic diffusion and dislocation ***,an understanding of the relationship between dislocation density and a special multistage creep behavior,i.e.,double steady creep feature,is still far *** we investigate the effect of various dislocation density levels on such an abnormal multistage creep of an Al-Cu-Li *** find that the increased dislocation densities enable an apparent time decrease(from 6.2 h to 0.8 h)of their first steadyⅡ-*** yield strength of post-aged sam-ples increases from 425.0 MPa to 580.0 MPa while the corresponding elongation decreases from 12.3%to 7.3%for the creep-aged samples#1 to#*** results also reveal that a great difference in dislocation configuration,tailored by various density levels,results in varying creep processes of theⅡ-*** stage is closely related to the nucleation and early growth of T_(1)*** number densities(maximum:2.9×10^(19)m^(-3))and the average length(maximum:21.3 nm)of T_(1)precipitates are much smaller than those of the stable peak-aged T_(1)phases,suggesting that creepⅡ-stage of all three creep-aged samples is dominant by the nucleation and initial growth of those T_(1)*** study provides valuable insights into the dislocation density-mediated creep deformation of an Al-Cu-Li alloy.

关键词： Dislocation density Al-Cu-Li alloy Creep ageing T_(1)precipitation

Approximate-model Based Estimation Method for Dynamic Response of Forging Processes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第3期28卷 565-572页

作者： LEI Jie LU Xinjiang LI Yibo huang minghui ZOU Wei State Key Laboratory of High Performance Complex Manufacturing Central South University

Many high-quality forging productions require the large-sized hydraulic press machine（HPM） to have a desirable dynamic response. Since the forging process is complex under the low velocity, its response is difficult to estimate. And this often causes the desirable low-velocity forging condition difficult to obtain. So far little work has been found to estimate the dynamic response of the forging process under low velocity. In this paper, an approximate-model based estimation method is proposed to estimate the dynamic response of the forging process under low velocity. First, an approximate model is developed to represent the forging process of this complex HPM around the low-velocity working point. Under guaranteeing the modeling performance, the model may greatly ease the complexity of the subsequent estimation of the dynamic response because it has a good linear structure. On this basis, the dynamic response is estimated and the conditions for stability, vibration, and creep are derived according to the solution of the velocity. All these analytical results are further verified by both simulations and experiment. In the simulation verification for modeling, the original movement model and the derived approximate model always have the same dynamic responses with very small approximate error. The simulations and experiment finally demonstrate and test the effectiveness of the derived conditions for stability, vibration, and creep, and these conditions will benefit both the prediction of the dynamic response of the forging process and the design of the controller for the high-quality forging. The proposed method is an effective solution to achieve the desirable low-velocity forging condition.

关键词： performance analysis forging process modeling hydraulic press machine

Formation of a new intermediate phase and its evolution toward θ’ during aging of pre-deformed Al-Cu alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第5期35卷 885-890页

作者： Peipei Ma Chunhui Liu Ziyao Ma Lihua Zhan minghui huang Light Alloy Research Institute of Central South University State Key Laboratory of High-Performance Complex Manufacturing Central South University Changsha 410083 China School of Mechanical and Electrical Engineering Central South University Changsha 410083 China

The frequent occurrence of hitherto unknown phase Pre-θ′-2 and unusual 1.5 cθ′thick θ′precipitate was observed by atomic-resolution scanning transmission electron microscopy in the well-studied Al-Cu alloys. This phenomenon is associated with heterogeneous precipitate nucleation and growth on preexisting dislocations introduced by slight deformation prior to aging. In this study, the precise structure details of Pre-θ′-2 was determined by atomic scale imaging, image simulation based on image forming theories and first principle calculations. Pre-θ′-2 has a well-defined ordered structure sandwiched between two 2 aAl(~1.5 cθ′) spaced Cu layers on {200}Alplanes. The strong structural similarities between Pre-θ′-2 and 1.5 cθ′ thick θ′ in terms of interfacial structure and thickness, coupled with energetic calculations and preliminary in-situ observations, lead us to propose a new precipitation path toward key strengthening phase θ′

关键词： Aluminum alloys Precipitation Deformation Age-harde ning

Improved creep aging response in Al-Cu alloy by applying pre-aging before pre-straining

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第7期36卷 518-530页

作者： Fangpu LYU Chunhui LIU Peipei MA Jianshi YANG Longhui CHEN Lihua ZHAN minghui huang State Key Laboratory of Precision Manufacturing for Extreme Service Performance School of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China Light Alloy Research Institute Central South UniversityChangsha 410083China Advanced Research Center Central South UniversityChangsha 410083China

The improvement of post-form properties without compromising creep formability has been a critical issue in creep age forming of aluminum alloy component. A pretreatment process incorporating artificial pre-aging at 165 °C for 6 h/12 h/24 h followed by pre-strain(3%–9%)has been developed. This method not only evidently improves the strength but also accelerates the creep deformation during creep aging of an Al-Cu alloy. A strength increase of 50 MPa with a slight decrease of ductility relative to the 9% pre-strained alloy is acquired in the alloy artificially pre-aged for 24 h regardless of the pre-strain level(3%–9%). Artificial aging for 24 h prior to 3%pre-strain enables an increase of creep strain by 30%. The creep strain in the alloy artificially preaged for 24 h and pre-strained by 6% is comparable to that in the alloy pre-strained by 9%. The strength and ductility in the alloy artificially pre-aged for 6 h/12 h and pre-strained by 3% are even slightly higher than those in the alloy purely pre-strained by 9%. The characterizations by transmission electron microscopy reveal that pre-aging at 165 °C could promote the accumulation of dislocations during pre-straining due to the pinning effect of pre-existing Guinier-Preston zones(GP zones)/θ’’phases and thus expedite the creep deformation in respect to the pure pre-straining treatment. The enhanced precipitation of θ’phases at these pinned dislocations contributes to the improved strength after creep aging. The results demonstrate applying artificial pre-aging before pre-straining is an efficient strategy to elevate the creep aging response in Al alloys.

关键词： Al-Cu alloy Creep aging Pre-aging Precipitation Pre-strain

Transient and stable electroluminescence properties of alternating-current biased organic light-emitting diodes

在线全文

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2012年第3期5卷 279-283页

作者： Jinzhao huang minghui SHAO Xijin XU School of Physics and Technology University of Jinan Jinan 250022 China

In this work, transient electroluminescence （EL）（brightness-voltage waveform curve） was utilized to investigate the working mechanism of alternating-current biased organic light-emitting diodes （AC-OLEDs）. In lower frequency domain, injection potential barrier was the dominant effect to determine the luminescence intensity; with increased frequency, the influence of capacitance effect becomes dominant, which can be confirmed according to the investigations on stable EL of the AC-OLEDs. The results indicate that transient and stable EL can agree with each other perfectly. Besides, the stable EL reveals that the thinner device can take more effective capacitance effect.

关键词： organic light-emitting diodes (OLEDs) alter-nating-current (AC) transient electroluminescence (EL)

Polystyrene microsphere-immobilized palladium(Ⅱ)porphyrin as mild,reusable,and highly efficient catalyst for Heck reaction

在线全文

学校读者我要写书评

暂无评论

Particuology 2015年第5期13卷 128-133页

作者： Yinbin huang Liangrong Yang minghui huang Jian Wang Lin Xu Wensong Li Huacong Zhou Xitong Sun Huifang Xing Huizhou Liu Key Laboratory of Green Processes and Engineering Institute of Process EngineeringChinese Academy of Sciences Agricultural & Biosystems Engineering South Dakota State University Art College Hubei University of Economics

A novel Heck reaction catalyst consisting of a palladium（ll） complex of meso-tetra（p- hydroxyphenyl）porphyrin （MTP） and cross-linked chloromethylated polystyrene microspheres （PMs） was successfully prepared via covalent ether bonds between the chloride groups in the PMs and the hydroxyl groups in MTP. The catalyst was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma atomic emission spectroscopy （ICP-AES）. This polystyrene-supported palladium-complex was an efficient heterogeneous catalyst for cross-coupling of aryl iodides with ethyl acrylate. The reaction of iodobenzene and ethyl acrylate under N2 at 100 °C and a catalyst concentration of 0.1% gave a gas chromatography product yield of 99.8%, which is much higher than that achieved using a free palladium（II） complex of MTP as the catalyst （41.3%）. The catalyst was recycled up to six times without significant loss of catalytic activity. These results suggest that the immobilized palladium（II） MTP catalyst has potential applications in synthetic and industrial chemistry.

关键词： Heterogeneous catalyst Palladium-porphyrin Polystyrene microspheres Heck reaction

Dislocation reconfiguration during creep deformation of an Al-Cu-Li alloy via electropulsing

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第35期130卷 27-34页

作者： Chang Zhou Lihua Zhan He Li Chunhui Liu Yongqian Xu Bolin Ma Youliang Yang minghui huang College of Mechanical and Electrical Engineering Central South UniversityChangsha410083China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha410083China Light Alloys Research Institute Central South UniversityChangsha410083China

Creep mechanism was well-known to be mainly dominated by the dislocation sliding and climbing during creep deformation. Here we study the creep deformation of an Al-Cu-Li alloy with the assistance of electropulsing and subsequent microstructural observations. We find that creep strain increased drastically under electropulsing and was almost twelve times as much as that of the non-pulsed sample. Microstructural observations confirmed that dislocation reconfiguration happens via electropulsing, namely helical dislocations being opened rapidly. This opened dislocation structure can possess a much higher mobility than the initial helical dislocation, which mostly responsible for the greatly increased creep strain. Our results revealed a new mechanism accountable for the distinctly electroplastic creep deformation.

关键词： Dislocation reconfiguration Electroplasticity Al-Cu-Li alloy Creep deformation

Hd1,Ghd7,and DTH8 synergistically determine the rice heading date and yield-related agronomic traits

在线全文

学校读者我要写书评

暂无评论

Journal of Genetics and Genomics 2022年第5期49卷 437-447页

作者： Kangli Sun minghui huang Wubei Zong Dongdong Xiao Chen Lei Yanqiu Luo Yingang Song Shengting Li Yu Hao Wanni Luo Bingqun Xu Xiaotong Guo Guangliang Wei Letian Chen Yao-Guang Liu Jingxin Guo State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources College of Life SciencesSouth China Agricultural UniversitySCAUGuangzhouGuangdong 510642China Guangdong Laboratory for Lingnan Modern Agriculture GuangzhouGuangdong 510642China

Heading date determines the seasonal and regional adaptation of rice(Oryza sativa L.)varieties and is mainly controlled by photoperiod sensitivity(PS).The core heading date genes Hd1,Ghd7,DTH8,and PRR37 act synergistically in regulating the *** this study,we systematically analyze the heading date,PS,and agronomic traits of eight homozygous lines with various combinations of Hd1,Ghd7,and DTH8 alleles in the prr37 background under long-day(LD)and short-day(SD)conditions,*** find that Hd1 alone promotes heading,regardless of the day ***,under LDs,Hd1 suppresses flowering,in coordination with functional Ghd7 or with Ghd7 and *** loci cooperate to negatively regulate the Ehd1-Hd3 a/RFT1 pathway and delay *** SDs,Hd1 competes with various heading suppressors to promote ***,the dual function of Hd1 is vital for *** lines carrying Hd1 alone show reduced plant height with fewer primary and secondary branches in *** carrying Ghd7 and DTH8(with hd1)show delayed heading and improve agronomic ***,our results reveal the regulation of rice PS flowering by the core heading date genes and their effects on agronomic traits,providing valuable information for the selection of rice varieties for adaptation to different light and temperature conditions.

关键词： Rice Photoperiod sensitivity Heading date Hd1 Agronomic traits

文化的解释——圣愚研究范式的分歧及其之于区辩异常的省思

在线全文

学校读者我要写书评

暂无评论

世界宗教文化 2023年第2期 33-42页

作者：黄明慧集美大学海洋文化与法律学院

在西里尔语的词源学中,圣愚的字义是指生来便带有印记的人,并将致力于神圣的志业。普遍认为,圣愚的概念源自拜占庭文化;而在东正教的文献中,圣愚则是对特定圣徒的称谓。圣愚的古怪行径,经常被视为关乎基督神性的道德意义及宗教目的。圣... 详细信息

在西里尔语的词源学中,圣愚的字义是指生来便带有印记的人,并将致力于神圣的志业。普遍认为,圣愚的概念源自拜占庭文化;而在东正教的文献中,圣愚则是对特定圣徒的称谓。圣愚的古怪行径,经常被视为关乎基督神性的道德意义及宗教目的。圣愚作为一类特殊的人物,学者研究的视角不尽相同。本文以圣愚为例,检视俄罗斯与西方学者针对这种文化现象的当代分析,并进一步思考区辩法则的标准,及因排斥异常人事所导致的人际疏离。

关键词：圣愚拜占庭萨满自闭症异常