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Simultaneously improving the strength and ductility of AZ91/GNPs composites through decorating graphene nanoplatelets with MgO

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Journal of Materials Science & Technology 2024年第16期183卷 133-151页

作者： Pingbo Wang Jun Shen Tijun Chen Jiqiang Ma qinglin li Shaokai Zheng State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050China

Magnesium matrix composites(MgMCs)have always suffered low strengthening efficiency and poor ductility due to the difficulties in pursuing the well-bonded ***,graphene nanoplatelets(GNPs)were decorated with magnesium oxide nanoparticles(MgO NPs)through chemical co-precipitation and then incorporated into AZ91 alloy to fabricate MgMCs via powder *** effect of MgO on the interface of the Mg/graphene system was investigated based on the first-principles calculations,and the result indicated that modifying GNPs with MgO NPs was helpful in improving the Mg-GNP interface *** interface structural analysis revealed that the MgO NPs were firmly bonded with both GNPs andα-Mg through the distortion area bonding and semi-coherent interfacial bonding,severing as a bridge to fasten the interface bonding of *** addition,the MgO NPs on GNPs acted as a barrier to prevent GNPs from seriously reacting with the AZ91 *** a result,the AZ91/MgO@GNPs composite was endowed with enhancements of 31%and 10%in the yield strength,and increments of 71%and 61%in elongation compared with the AZ91 alloy and AZ91/GNPs composite,respectively,exhibiting a more significant potential in optimizing the strength-toughness tradeoffcompared with the AZ91/***,the possible strengthening and toughening mechanisms were also discussed in *** work offers a relatively novel surface modification strategy to modulate the Mg-GNP interface for a simultane-ous improvement of strength and ductility.

关键词： Graphene nanoplatelets Magnesium oxide First-principles calculations Magnesium matrix composites Powder thixoforging

Preparation and luminescence characteristics of Sr_3SiO_5:Eu^(2+) phosphor for white LED

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Chinese Science Bulletin 2008年第7期53卷 974-977页

作者： li PanLai YANG ZhiPing WANG ZhiJun GUO qinglin li Xu College of Physics Science and Technology Hebei University Baoding 071002 China

The Sr3SiO5:Eu2+ phosphor was synthesized by high temperature solid-state reaction. The emission spectrum of Sr3SiO5:Eu2+ shows two bands centered at 487 and 575 nm, which well agree with the theoretic values of emission spectrum. The excitation spectrum for 575 nm emission center has several excitation bands at 365, 418, 458 and 473 nm. And the results show that the emission spectrum of Sr3SiO5:Eu2+ is influenced by the Eu2+ concentration. The relative emission spectra of the white-emitting InGaN-based YAG:Ce3+ LED and Sr3SiO5:Eu2+ LED were investigated. The results show that the color development of InGaN-based Sr3SiO5:Eu2+ is better than that of InGaN-based YAG:Ce3+, and the CIE chromaticity of InGaN-based Sr3SiO5:Eu2+ is (x=0.348, y=0.326).

关键词：发光性无机发光材料白光二极管性状

Fabrication of graphene nanoplatelets reinforced Mg matrix composites via powder thixoforging

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Journal of Magnesium and Alloys 2022年第11期10卷 3113-3132页

作者： Pingbo Wang Jun Shen Tijun Chen qinglin li Xiao’an Yue lingyun Wang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou730050China

A powder thixoforging route combined with slurry based mixing process was proposed to fabricate graphene nanoplatelets(GNPs) reinforced magnesium matrix composites(MgMCs). The originally spherical and ball-milled ZK60 powders were used as matrices, *** mixing of 0.05 wt.% GNPs with the spherical powder led to GNPs clusters and degraded the mechanical properties of the *** contrast, with the addition of an optimal content(0.1 wt.%) of GNPs, the composite fabricated from ball-milled powder achieved a joint enhancement in tensile yield strength(52%) and fracture toughness(19%), demonstrating a pronounced strengthening efficiency of 650% and a good balance between strength and toughness. The ball-milled powder endowed the composite with a homogenous distribution of GNPs and a denser microstructure with reduced Mg-Zn eutectics, and the thixoforging process offered a well-bonded Mg/GNP interface, making full use of the strengthening and toughening potential of GNPs. Theoretical predication based on a modified shear-lag model suggested that load transfer dominated the strengthening mechanisms. In-situ tensile tests verified that crack deflection, secondary cracks and GNPs bridging mainly accounted for the toughening mechanisms. A numerical model with consideration of GNPs orientations was also established to understand the toughening effect from GNPs bridging.

关键词： Graphene nanoplatelets(GNPS) Magnesium Powder thixoforging Strengthening Toughening

Piezoelectric film promotes skin wound healing with enhanced collagen deposition and vessels regeneration via upregulation of PI3K/AKT

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Nano Research 2024年第8期17卷 7461-7478页

作者： Qi Xu Wufei Dai Peizhe li qinglin li Zhen Gao Xiaoli Wu Wei liu Wenbo Wang Department of Plastic and Reconstructive Surgery Shanghai Key Laboratory of Tissue EngineeringShanghai Ninth People’s HospitalShanghai Jiao Tong University School of MedicineShanghai 200011China Research Institute of Plastic Surgery Shandong Second Medical UniversityWeifang 261000China Department of Surgery Air Force Medical CenterPLABeijing 100142China

Skin wounds are common in accidental injuries,and the intricacies of wound repair are closely linked to endogenous electric *** stimulation plays a pivotal role in the restorative processes of skin injuries,encompassing collagen deposition,angiogenesis,inflammation,and *** electrical stimulation therapy replicates and enhances the effects of endogenous wound electric fields by applying an external electric field to the wound site,thereby promoting skin wound *** this study,we developed a self-powered repetitive mechanical impacts-electrical stimulation(RMI-ES)system utilizing a BaTiO_(3)/polydimethylsiloxane(PDMS)piezoelectric composite *** to conventional electrical stimulation devices,the fabricated piezoelectric composite film efficiently harvests energy from the pressure applied by the stimulation device and the tensile force occurring during natural rat *** results demonstrated that piezoelectric stimulation generated by the composite membrane expedited the cell cycle,promoting fibroblast ***,piezoelectric stimulation induced favorable changes in fibroblast gene expression,including increased expression of transforming growth factor-β1(TGF-β1),connective tissue growth factor(CTGF),collagen 1,collagen 3,vascular endothelial growth factor(VEGF),and alpha-smooth muscle actin(α-SMA),while reducing interleukin-6(IL-6)*** analysis revealed that piezoelectric stimulation may induce fibroblast migration,proliferation,and collagen expression by influencing PI3K/AKT serine/threonine kinase(AKT)*** confirmation through the addition of the PI3K inhibitor LY294002 validated that piezoelectric stimulation can regulate the repair process after skin injury through the ***,in vivo results demonstrated that the electric field at the wound site effectively promoted wound healing,reduced inflammation,and stimulated collagen deposition and ne

关键词： BaTiO3/polydimethylsiloxane(PDMS)nano-composite membrane piezoelectrical stimulation skin wound healing collagen deposition PI3K/AKT serine/threonine kinase(AKT)signaling pathway

Contribution of plant traits to the explanation of temporal variations in carbon and water fluxes in semiarid grassland patches

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Journal of Plant Ecology 2020年第6期13卷 773-784页

作者： Mengyu Wang Nan Lu qinglin li Weiwei Fang Bojie Fu State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China College of Forestry and Biotechnology Zhejiang Agriculture and Forestry UniversityHangzhou 311300China Key Research Institute of Yellow River Civilization and Sustainable Development Henan UniversityKaifeng 475001China School of Natural Resources Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China

Aims Accurate prediction of spatiotemporal variations in carbon and water fluxes of heterogeneous landscape is critical to comprehensively address the effects of climate change and vegetation dynamics on landscape and regional carbon and water *** A field study was conducted to characterize the seasonal variations in gas fluxes and explore their relationships with abiotic and biotic factors in a small grassland *** carbon and water fluxes including net ecosystem exchange,gross ecosystem productivity,ecosystem respiration and evapotranspiration(ET)were measured for three types of grassland patches over a growing season using the closed chamber *** key plant trait variables were measured,based on which community weighted mean(CWM)and functional variance(FDvar)were *** Findings The results showed that the temporal variations in the carbon and water fluxes were regulated by meteorological,soil and community functional *** of the CWM and FDvar of plant trait measures greatly improved the degree of explanation of the predict *** leaf area and leafδ^(13)C content(Lδ^(13)C)were the most important trait variables in affecting the variations of the gas *** indices had greater importance than FDvar indices in predicting the variation of the C fluxes but FDvar indices were more important for ET than C *** findings demonstrated that mass ratio hypothesis and the complementary effects hypothesis are not mutually exclusive but have different relative importance for different ecosystem *** functional traits played important roles in predicting the spatiotemporal variations of carbon and water fluxes in semiarid grassland.

关键词： plant functional trait functional diversity carbon and water fluxes semiarid area Loess Plateau

Effect of aging on the mechanical properties and corrosion susceptibility of an Al-Cu-li-Zr alloy containing Sc

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Rare Metals 2008年第2期27卷 146-152页

作者： liANG Wenjie PAN qinglin HE Yunbin li Yunchun ZHOU Yingchun LU Congge School of Materials Science and Engineering Central South University Changsha 410083 China

The effects of aging on the microstructure, mechanical properties, intergranular corrosion, and exfoliation corrosion of an Al-3.5Cu-1.5li-0.22（Sc ＋ Zr） alloy have been investigated. The results show that the alloy has the character of age hardening, and the major phase of precipitation and strengthening is the T1 phase. The aging temperature and aging time have a significant effect on the amount and distribution of the T1 phase. The proper artificial single-aging treatment of the alloy is at 160℃ for 40 h. The intergranular corrosion and exfoliation corrosion of the alloy are caused by the anodic dissolution of the T1 phase and the precipitate-free zone （PFZ）. With increasing the aging time to overaged, the T1 phase coarsens, and the PFZ widens, leading to an increase in the susceptibility to intergranular corrosion and exfoliation corrosion.

关键词： Al-li alloys aging microstructure T1 phase corrosion

Visible-light responsive organic nano-heterostructured photocatalysts for environmental remediation and H2 generation

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Journal of Materials Science & Technology 2020年第3期38卷 93-106页

作者： Yingzhi Chen Dongjian Jiang Zhengqi Gong qinglin li Ranran Shi Zexi Yang Ziyi Lei Jingyuan li Lu-Ning Wang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

The ease of molecular design and functionalization make organic semiconductors(OSCs)unit the electronic,chemical and mechanical benefits with a material *** easily tunable optoelectronic properties of OSCs also make it promising building blocks and thereby provide more possibilities in photocatalytic *** far,organic nanostructures have gained great impetus and found wide applications in photocatalytic organic synthesis,remediation of water and air,as well as water splitting into *** they still suffer from low charge separation and sunlight absorption ***,many strategies have been explored to address these issues,and one of the most effective solutions is to develop *** give an impulse for the developments of this field,this review attempts to make a systematic introduction on the recent progress over the rational design and fabrication of organic nano-heterostructured photocatalysts,including the types of organic semiconductor/semiconductor(OSC/SC),organic semiconductor/metal(OSC/M),organic semiconductor/carbon(OSC/C),and OSC-based multinary *** emphasis is placed on the structure/property relationships,and their photocatalytic purposes in environmental and energy *** last,future challenges and perspectives for the ongoing development of OSC materials and their use in high-quality optoelectronic devices are also covered.

关键词： Organic semiconductor Nanostructure Heterostructure Photocatalyst

Effects of AlCoCrFeNiTi high-entropy alloy on microstructure and mechanical properties of pure aluminum

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Journal of Materials Science & Technology 2020年第17期52卷 1-11页

作者： qinglin li Shang Zhao Xuepeng Bao Yushi Zhang Yuqian Zhu Chuangzao Wang Yefeng Lan Yuxin Zhang Tiandong Xia School of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050China State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China

A new kind of AlCoCrFeNiTi high-entropy alloy(HEA)as a grain refiner was prepared by vacuum arc *** this work,the effects of HEA(1.0 wt.%,2.0 wt.%and 3.0 wt.%)on the microstructure and mechanical properties of pure aluminum were *** microstructure was characterized and examined by scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),electron probe micro-analyzer(EPMA)and transmission electron microscopy(TEM)to indicate the refining abilities and mechanism of HEA on pure *** show that the addition of HEA refined both the macrostructure and microstructure of pure *** 1.0 wt.%HEA was added,most coarse columnar grains were refined into equiaxed crystals,and as the amount of HEA increased to 2.0 wt.%and3.0 wt.%,aluminum grains were further refined,and the grain boundaries were nearly ***,the morphology ofα-Al transformed from coarse columnar crystals to equiaxed grains,and the mean size ofα-Al grains decreased from 374μm to 27μ*** Al3Ti,Al3Ni,and nano-phase precipitated from the aluminum alloy with HEA in the *** typical rod-like nano-phases distributed interdendritic regions ofα-*** average length of nano-phases is 2568 nm,4372 nm,and 6907 nm and the average diameter is 112 nm,103 nm,and 92 nm when 1.0 wt.%,2.0 wt.%and 3.0 wt.%HEA were added to the pure aluminum,*** ultimate tensile strength(UTS)and yield strength(YS)were improved in all samples,whereas the elongation(El)was decreased with increasing HEA *** 3.0 wt.%HEA was added into the aluminum melt,the UTS was improved by 145.2%from62 MPa to 152 MPa,the YS was increased by 173.8%from 42 MPa to 115 MPa,and the El was decreased by 33.3%from 39%to 26%.

关键词： Pure aluminum High-entropy alloy α-Al phases Nano-phases Mechanical properties

Phase Transformation Strengthening of Hot Extruded Inconel 625 under High-temperature Load Environment

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Journal of Wuhan University of Technology(Materials Science) 2019年第6期34卷 1297-1308页

作者： liU Dexue CUI Maomao WANG Wenxu NAN Hongqiang CAI Haopeng XUE Hongdi JIA Zhi li qinglin State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of TechnologyLanzhou 730050China School of Material Science and Engineering Lanzhou University of TechnologyLanzhou 730050China Jinchuan Nickel-Metropolis Industrial Company Jinchang 737100China Jinchuan Group Nickel Alloy Co. Lanzhou 730100China

Microstructure evolution and properties of hot-extruded Inconel 625 alloy were investigated at different creep temperatures, aging time and strain rates. The experimental results indicate that the Inconel 625 alloy exhibits an excellent creep resistance at 700 ℃ and below. When the creep temperature rises to 750 ℃, the creep resistance falls drastically due to the failure of phase transformation strengthening and the precipitation of a large amount of δ phase and σ phase at the grain boundary. The special temperature-sensitive characteristics of Inconel 625 alloy play a very important role in its fracture. When the strain rate is 8.33×10^-3s^-1, the strength of the specimen is higher than that of other parameters attributed to the effect of phase transformation strengthening. With the increase of Ni3(Al, Ti), the phase transformation strengthening inhibits thickening of the stacking faults into twins and improves the overall mechanical properties of the alloy. With the increase of the aging time, the granular Cr-rich M23C6 carbides continue to precipitate at the grain boundary, which hinders the movement of the dislocations and obviously increases the strength of the samples. Especially, the yield strength increases several times.

关键词： hot-extruded Inconel 625 alloy phase transformation strengthening temperature sensitivity characteristics Cr-rich M23C6 carbides δphase