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Microstructure Evolution of Semi-solid Processed Hyper-eutectic Al-30%Si Alloy

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International Journal of Minerals,Metallurgy and materials 1999年第4期13卷 259-261页

作者： Yanjun li weimin {2. Xueyou Zhong(Material science and engineering school, university of science and technology Beijing, Beijing 100083, china) Material science and engineering {2. University of Science and Technology Beijing Beijing 100083 China

An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.

关键词： semi-solid state process solidification structure mechanical stirring hyper-eutectic Al-Si alloy

Acceptor-planarized typeⅠphotosensitizer for lipid droplet-targeted two-photon photodynamic therapy by ferroptosis

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science china Chemistry 2024年第7期67卷 2392-2402页

作者： Jie sha weimin {2.u Jiasheng Wu Yanping Wang Xuewei {2. Haohui Ren Zhi Pang Wenjun Zhang Chun-Sing Lee Pengfei Wang Key Laboratory of Photochemical Conversion and Optoelectronic materials CityU-CAS Joint Laboratory of Functional Materials and DevicesTechnical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China school of Future technology University of Chinese Academy of SciencesBeijing 100049China Center of Super-Diamond and Advanced Films&Department of materials science and {2. City University of Hong KongHong KongChina

Two-photon photodynamic therapy(TP-PDT)has garnered significant attention because of its excellent depth of tissue penetration and high spatiotemporal ***,the limited targeting ability and oxygen dependency of photosensitizers(PSs)significantly hinder the effectiveness of photodynamic therapy in hypoxic tumor ***,we designed and synthesized two lipid droplet(LD)-targeted two-photon PSs(TBPCP and TBCP)by reducing benzene rings to achieve“acceptor planarization”.Notably,acceptor planarization not only enhanced the intramolecular charge transfer but also transferred the photochemical reaction from typeⅡ(TBPCP)to typeⅠ(TBCP).Under the irradiation of 940 nm femtosecond pulsed laser,TBPCP and TBCP showed bright two-photon-excited fluorescence and excellent LD targeting in living *** TBPCP(typeⅡPS),the outstanding TP-PDT efficacy of TBCP(typeⅠPS)under hypoxic conditions could be obtained in both cellular experiments and multicellular tumor spheroids(MCTS)***,both TBPCP and TBCP could induce the lipid peroxidation in the typeⅠor typeⅡPDT due to the location of LD,depleting GSH and inactivating GPX4 to induce nonprogrammed ferroptosis in cells.

关键词： two-photon photodynamic therapy lipid droplet targeting acceptor planarization hypoxia tumor ferroptosis

Temperature Field and Microstructural Formation of Semi-Solid AlSi_7Mg Alloy

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International Journal of Minerals,Metallurgy and materials 2000年第2期14卷 99-102页

作者： weimin mao Aimin Zhao Yan jun {2. Cheng{2.n Cui Feng Sun Xuryou Zhong(Material science and engineering school, university of science and technology Beijing, Beijing 100083, china) Material science and engineering {2. University of Science and Technology Beijing Beijing 100083 China

The microstructural formation of the semi-solid AlSi7Mg alloy stirred by electromagnetic field is investigated together withthe tempeatre field of the stirred melt at continuously cooling. A impoat kinetic factor for primny a-Al nucleation is proposed. It isfound that a low temperatUre gradient exists in the electromagnetic stirred melt. This is why the first dendritic arms and secondary de-ndritic arms are refmed. Experimefltal results also show that the root remelting of secontw dendritic arms is an twortat mechanismfor the primary α-Al refmement. Strong electromagnetic stirring greatly reduces the composition supercooling in the melt and eliminatesprefedrig growth of the first dendritic arms. Therefore, many rosettes or spherical Primary α-Al phase particles form finally.

关键词： AlSi_7Mg alloy semi-solid electromagnetic stirring

半固态改性6061铝合金流变压铸试样组织及力学性能

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特种铸造及有色合金 2024年第4期44卷 516-520页

作者：张荣晟毛卫民李乃拥北京科技大学材料科学与工程学院北京100083

采用石墨质蛇形通道浇注复合流变压铸工艺进行半固态改性6061铝合金流变压铸成形。对比分析了传统液态压铸和流变压铸的改性6061铝合金试样的显微组织;研究了Si含量对半固态改性6061铝合金流变压铸试样组织及力学性能的影响。结果表明,... 详细信息

采用石墨质蛇形通道浇注复合流变压铸工艺进行半固态改性6061铝合金流变压铸成形。对比分析了传统液态压铸和流变压铸的改性6061铝合金试样的显微组织;研究了Si含量对半固态改性6061铝合金流变压铸试样组织及力学性能的影响。结果表明,相比于传统液态压铸,半固态改性6061铝合金流变压铸试样组织中的初生α-Al晶粒明显细化和球化,由粗大的枝晶演变为细小的球状晶或近球状晶。增加Si含量可以有效细化试样组织中的初生α-Al晶粒,并提升流变压铸试样的力学性能,当Si含量由0.6%增加至2.6%时,初生α-Al的平均晶粒直径由58μm左右逐渐减小至31μm左右,抗拉强度由(107±4)MPa逐渐增加至(2.9±14)MPa,伸长率由2.2.±0.3%逐渐增加至5.5%±0.5%。

关键词： 6061铝合金半固态流变压铸显微组织力学性能

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Analysis of the Transformation-induced Plasticity Effect during the Dynamic Deformation of High-manganese Steel

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Journal of materials science & {2. 2015年第2期31卷 191-198页

作者： Huizhen Wang Xiurong Sun Ping Yang weimin mao {2. Meng school of materials {2. and engineering University of Science and Technology Beijing

The transformation-induced plasticity(TRIP) effect and resistance characteristics to adiabatic shear failure at high strain rates of high-manganese steel were investigated by using scanning electron microscopy and electron backscattering diffraction. Results showed that the high-manganese steel exhibited excellent strain hardening effect and resistance to adiabatic shear failure because of the TRIP effect. The TRIP effect occurred during dynamic deformation and showed two distinct stages,namely,the smooth TRIP process before the formation of adiabatic shear band(ASB) and the inhibited TRIP process during further deformation. In the first stage,the martensitic transformation showed slight orientation dependence and weak variant selection,which promoted the TRIP effect. In the second stage,reverse martensitic transformation occurred. Adiabatic shear bands(ASBs) developed typical shear microtextures {111}. In microtextures,two groups of fine grains are in a twin relationship and uniform distribution,which restrained the formation of holes and cracks within the ASBs and enhanced damage resistance after ASB formation.

关键词： High-manganese steel Martensitic transformation Ad

Preparation of semisolid AlSi7Mg alloy slurry through weak traveling-wave electromagnetic stirring

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International Journal of Minerals,Metallurgy and materials 2009年第5期16卷 554-558页

作者： Zhen-duo Zhao Wei-min mao sha {2. Rong-mao Zhong school of materials {2. and engineering University of Science and Technology Beijing Beijing 100083 China

The semisolid AlSi7Mg alloy slurry with large capacity was prepared by low superheat pouring and week traveling-wave electromagnetic stirring. The effects of electromagnetic stirring power and frequency on the {2.pe and distribution of primary α-A1 grains in the AlSi7Mg alloy slurry were discussed. The experimental results show that the AlSi7Mg alloy slurry with fine and spherical primary α-A1 grains distributed homogeneously can be obtained. Under the condition of low superheat pouring and week traveling-wave electromagnetic stirring, when the pouring temperature is 630℃, raising the stirring power or frequency appropriately can gain a better {2.pe of primary α-Al grains; but if the stirring power or frequency is increased to a certain value （1.72.kW or10 Hz）, the {2.pe of primary α-A1 grains cannot be obviously improved and spherical primary α-Al grains distributed homogeneously can be still obtained.

关键词： semisolid AlSi7Mg alloy slurry electromagnetic stirring primary a-A1

Early-stage nucleation of manganese sulfide particle and its processing evolution in Fe-3wt.%Si alloys

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Frontiers of materials science 2016年第1期10卷 66-72页

作者： Wei GUO li MENG Hongcai WANG Guochun YAN weimin {2. Department of Microstructures and Alloy Design Max-Planck Institute for Eisenforschung Desseldorf 40237 Germany 2.school of materials {2. and engineering University of Science and Technology Beijing Beijing 100083 China Department of Beijing Research and Development East China Branch of Central Iron and Steel Research Institute Beijing 100081 China Institute fur Werkstoffe Ruhr-Universitat Bochum Bochum 44801 Germany

Manganese sulfide is often referred to as one of important inhibitors in grain-oriented electrical steels, which is of great importance to yield strong Goss texture. However, the early stage of nucleation for such inhibitors and their evolution during the processing has not been well understood. In present work we selected a Fe-3.12.t.%Si- 0.11wt.%Mn-0.02.wt.%S model system and used FE-SEM and atom probe tomography （APT） to investigate the precipitation behavior of MnS inhibitors at near atomic scale. It was found that the Si-S enriched clusters with sizes of 5-15 nm were formed close to the MnS particles. The density of inhibitors decreased after large pseudo-plane-strain compression because of the effect of dislocation motion, and then slightly increased again when sample was aged at 2.0℃ for 48 h. The dislocations and grain boundaries can act as fast diffusion paths and assist the reemergence of Si-S enriched clusters.

关键词： manganese sulfide (MnS) inhibitor nucleation precipitation grainoriented electrical steels

KH-560和玻璃粉对硅树脂涂层热防护性能的影响

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材料保护 2024年第8期57卷 198-205页

作者：罗屹峰廖桓毅蒋耀年戴翠英李沙吴志远左劲旅张伟毛卫国长沙理工大学材料科学与工程学院湖南长沙410014 高端装备先进涂层技术湖南省重点实验室湖南长沙410014 湖南博云新材料股份有限公司湖南长沙410205

为进一步提高硅树脂涂层的力学性能与服役温度,研究了硅烷偶联剂KH-560和低熔点玻璃粉对硅树脂涂层热防护性能的影响。采用高温型固体材料动态弹性性能测试仪、万能电子拉伸机、膨胀仪、燃气热冲击实验系统表征涂层的弹性模量、结合强... 详细信息

为进一步提高硅树脂涂层的力学性能与服役温度,研究了硅烷偶联剂KH-560和低熔点玻璃粉对硅树脂涂层热防护性能的影响。采用高温型固体材料动态弹性性能测试仪、万能电子拉伸机、膨胀仪、燃气热冲击实验系统表征涂层的弹性模量、结合强度、热膨胀系数、烧蚀、隔热、热冲击性能;采用红外光谱仪、发射扫描电子显微镜及其附带的能谱分析涂层组成、表面微观形貌、元素含量。结果表明:随着KH-560含量的增加(0~3%),硅树脂涂层的弹性模量和结合强度先增加后减少。当加入2.0%KH-560时,在常温下涂层的弹性模量和结合强度达到最大值,分别为2..10 GPa、4.40 MPa,这主要是因为KH-560使得硅树脂和金属基底之间的键合以及填料与硅树脂之间的键合增强。掺入110%的玻璃粉时,能够有效改善硅树脂涂层在800℃的热稳定性和抗热震性能,这是由于熔化的玻璃粉可填补硅树脂分解所产生的孔隙,从而阻止硅树脂进一步氧化分解。此外,玻璃粉含量为110%的硅树脂涂层具有良好的隔热和烧蚀性能。

关键词：耐高温硅树脂涂层硅烷偶联剂低熔点玻璃粉力学性能热学性能

Highway constructions on the Qinghai-Tibet Plateau:Challenge,research and practice

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Journal of Road engineering 2022年第1期2卷 1-60页

作者： Aimin sha Biao Ma Hainian Wang liqun Hu Xuesong {2. Xilan Zhi Huaxin Chen Yu liu Feng Ma Zhuangzhuang liu Rui He Wei Si Xuhao Wang Cheng li Key Laboratory of Special Area Highway engineering of Ministry of Education Chang'an UniversityXi'an 710064China school of Highway Chang'an UniversityXi'an 710064China Chang'an-Dublin International College of Transportation Chang'an UniversityXi'an 710064China school of materials {2. and engineering Chang'an UniversityXi'an 710064China

Highway constructions on the Qinghai-Tibet Plateau(QTP)face great challenges induced by the unique local environmental,geological,and engineering *** large area of permafrost,great temperature variability,strong UV rays,and complex geological conditions are the major factors that adversely influence the longterm performance of pavement *** 1960s,Chinese engineers and researchers have started conducting research on the QTP to enhance the performance and durability of pavement *** present paper provide a comprehensive review of challenge,research and practice of highway constructions on the QTP including the special environmental and geological conditions,history of highway constructions on the QTP,major challenges and the state-of-the-art technology of subgrade constructions on permafrost,developments of the pavement structures and materials,performance prediction and maintenance methods of pavement surfaces,and applications of the research achievements on the first expressway on the QTP(i.e.,Gongyu Expressway).Based on the comprehensive literature review,it can be found that(1)frost heave and thaw weakening induced subgrade disease and longitudinal cracks on the pavement surface are complex coupled water-thermal-load *** solutions are focusing on active cooling and thermal insulation methods,which can help to reduce temperature variations in the subgrade and thus improving its stability,(2.the harsh environmental and construction conditions may reduce the early strength and induce premature damage of cement-treated base *** field validations showed that geocell-reinforced or asphalt-treated flexible base materials can provide better long-term performance,(3)the large temperature variability and strong UV rays can significantly accelerate aging of asphalt binders and greatly reduce the service life of asphalt *** binder modification methods were developed for improving their viscoelasticity and enh

关键词： Qinghai-Tibet Plateau Permafrost subgrade Asphalt pavement Gongyu Expressway