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Superplastic behavior of an ultrafine-grained Mg-13Zn-1.55Y alloy with a high volume fraction of icosahedral phases prepared by high-ratio differential speed rolling

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journal of Materials Science & technology 2017年第9期33卷 919-925页

作者： t.Y.kwak W.j.Kim Rare Metal R&BD Group Korea Institute of Industrial Technology Department of Materials Science and Engineering Hongik University

An ultrafine-grained（UFG） Mg-13Zn-1.55 Y alloy（ZW132） with a high volume fraction（7.4%） of icosahedral phase（I-phase, Mg;Zn;Y） particles was prepared by applying high-ratio differential speed rolling（HRDSR） on the cast microstructure following homogenization. the alloy exhibited excellent superplasticity at low temperatures(tensile elongations of 455% and 1021% 473 K-10;s;and 523 K-10;s;,respectively). Compared with UFG Mg-9.25Zn-1.66 Y alloy（ZW92） with a lower volume fraction of I-phase particles（4.1%）, which was prepared using the same processing routes, the UFG ZW132 alloy exhibited a higher thermal stability of grain size. Rapid grain coarsening, however, occurred at temperatures beyond523 K, leading to a loss of superplasticity. the high-temperature deformation behavior of the HRDSRprocessed ZW132 alloy could be well described assuming that the mechanisms of grain boundary sliding and dislocation climb creep competed with each other and considering that the grain-size was largely increased by accelerated grain growth at the temperatures beyond 523 K.

关键词： Magnesium alloy Superplastic deformation Ultrafine grain Icosahedral quasicrystal Grain growth

Study of residual stresses in tailor rolled blanked Al5j32-t4 sheets

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Rare Metals 2006年第Z2期25卷 111-117页

作者： KIM Dongok KIM jinpyeong LEE Yong kwak Heeman RYU Yongmun HAN Beomsuck Materials & Processing Research Center Korea Automotive Technology Institute (KATECH) 74 Yongjung Ri PungseMyun Chonan Chungnam 330-912 Korea

Several automotive parts such as door panels have been manufactured by using load-adapted blanks for crash optimization and weight minimization. Recently, tailor Rolled Blanks (tRB) has been introduced to remove the disadvantages of a welding process which was used in joining panel components. tRB offers better structural design capabilities due to the seamless transitions on the panels with different thicknesses. In spite of the advantages of the process, tRB leaves internal stresses in the panel. this residual stresses lower the formability of tailor Rolled Blanked (tRBed) parts and cause cracks near severe curvature during subsequent forming processes. In this research, the residual stresses of tRBed Al5j32-t4 sheets were studied by X-ray stress analysis, and also microstructure was observed along the rolling direction. In addition, heat treatment was done after tRB process in order to compare the residual stresses to that of the tRBed sheets before the heat treatment.

关键词： tailor rolled blanks residual stresses deformation microstructure

Portable System for CWA Detection Using Micro Array Gas Sensor

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稀有金属材料与工程 2006年第A3期35卷 124-128页

作者： j.H.kwak Y.t.Lim G.H.Kim N.j.Choi H.D.Park G.H.Rue j.S.Huh j.C.Kim D.D.Lee School of Electrical Engineering and Computer Science Kyungpook National UniversityDaegu 1370Korea Electronics and telecommunications Research Institute Future Technology Research Division New Functional Information Devices TeamGajeongYuseong-GuDaejeon 161 Korea Korea Electronics technology Institute Yatap-DongBundang-GuSeongnam-SiGyeonggi-Do #68Korea Department of Materials Science and Metallurgy Kyungpook National UniversityDaegu 1370Korea Department of Chemical Engineering Kyungpook National UniversityDaegu 1370Korea

Biochemistry weapon is raising new tools of war and *** research is an experiment about portable system for CWAs (chemical warfare agents) detection using micro array gas *** were divided into four types such as blood, nerve,vesicant,and choking *** detect various CWAs,semiconductor thick film sensor array based on tin oxide was fabricated and their gas responses were *** temperature was range of 250℃to 350℃and gas concentration was range of 0.1μg/g to 10μg/*** array was measured as operating temperatures,concentrations for four simulant agents of *** parameters from results were carried out classification among CWAs through the principal component analysis (PCA).Also,classification of gases is studied using adaptive resonance theory (ARt) that is one of neural network *** displayed using PDA system.

关键词： SnO2 chemical warfare agents(CWAs) portable system ARt array PCA

Generation of brain vascular heterogeneity:recent advances from the perspective of angiogenesis

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Neural Regeneration Research 2025年第7期20卷 2013-2014页

作者： Nathanael j.Lee Ryota L.Matsuoka Department of Neurosciences Lerner Research InstituteCleveland ClinicClevelandOHUSA Department of Molecular Medicine Cleveland Clinic Lerner College of MedicineCase Western Reserve UniversityClevelandOHUSA

Heterogeneous proper t i es of vascular endothelial cells in the brain:the brain displays large energy dynamics and consumption,and this high level of metabolic demands is fulfilled by a continuous supply of glucose and oxygen through its vascular *** vasculature consists of highly divergent blood vessel branches,giving rise to a dense network of capillaries that supply blood to all cells across the *** elaborated vascular network is thought to develop via angiogenesis,a process in which new blood vessels grow from pre-existing *** capillaries exhibit organotypic features distinct from other tissues and are formed primarily by two major endothelial cell(EC)types:those that form the semi-permeable blood-brain barrier(BBB)and those that develop highly permeable pores known as fenestrae(Matsuoka et al.,2022).the structural and functional differences between BBB and fenestrated vascular ECs represent a fundamental feature of brain vasculature and form the foundation for both brain function and homeostasis.

关键词： angiogenesis homeostasis network

the mean value concept in mono-linear regression of multi-variables and its application to trace studies in geosciences

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Science China Earth Sciences 2007年第12期50卷 1828-1834页

作者： A j t jULL NSF-AMS laboratory University of Arizona

the "mean value concept" in a mono-linear regression of multi-variables is *** applications to reconstruction of the past 90-year salinity of the sea surface water in Xisha Islands and to tracing the past 80 ka paleo-geomagnetic events from the Luochuan loess 10Be record are introduced in detail,which show the significance and the potential of the "mean value concept" in geoscience research.

关键词： mean value concept, linear regression, trace, reconstruction

Effect of surface layer softening from previous electrochemical corrosion on electrochemical cold drawing of Q235 steel bar

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journal of Iron and Steel Research International 2022年第5期29卷 819-835页

作者： j.L.Guo t.j.Chen State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou730050GansuChina

the effects of H_(2)SO_(4)concentration and current in electrochemical corrosion on surface layer softening or plasticizing of Q235 steel bar and their effects on subsequent electrochemical cold drawing(ECD)were *** results indicate that the electrochemical corrosion can soften or plasticize the surface layer of Q235 steel bar and then make the subsequent ECD be conducted more *** softening degree and thickness of the surface layer are continuously enhanced with increasing corrosion rate,i.e.,increasing H_(2)SO_(4)concentration or current,due to the generation of more vacancy clusters in deeper regions of surface *** vacancy clusters then relax dislocations through being absorbed during ECD,and the formation and movement of additional dislocation flux are thereby enhanced,resulting in the further obvious decrease in the drawing *** is also due to the enhanced formation and movement of additional dislocation flux that the dislocation density and thus the hardness of the surface layer are decreased,as well as that the texture structure is *** behaviors are enhanced as the corrosion rate increases.

关键词： Electrochemical corrosion Electrochemical cold drawing Surface layer softening Vacancy Additional dislocation flux

Microstructure and Mechanical Properties of tiB-Containing Al–Zn Binary Alloys

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journal of Materials Science & technology 2016年第7期32卷 653-659页

作者： Sang-Soo Shin Gil-Yong Yeom tae-Yang kwak Ik-Min Park Department of Materials Science and Engineering Pusan National University Busan 609-735 Republic of Korea Liquid Processing & Casting technology R&BD Group Korea Institute of Industrial Technology Incheon 21999 Republic of Korea

the microstructure and mechanical properties of newly developed Al-35Zn cast alloys with tiB refiner addition were evaluated by X-ray diffractometry, optical microscopy, and scanning electron microscopy coupled with energy dispersive spectrometry. the microstructure of these alloys featured α-Al den- drites surrounded by AI-Zn （α ＋ rI） eutectic structures. After the addition of tiB refiner, the alloy grain sizes decreased, and its morphology abruptly changed from dendritic to equiaxed grains. Such an im- proved microstructure of the modified alloys was accompanied by a significant increase in the tensile strength and elongation percentage compared to those of the AI-Zn or Zn-Al-based alloys. the results showed that with the increase of tiB content up to 0.05%, the morphology of α-Al dendrites and α ＋ t1 phases changed from coarse dendrite and lamellar structures into independent and fine ones. Based on these results, the effect of tiB refiner addition on the microstructure and mechanical properties of the AI-35Zn binary alloys was investigated.

关键词： Al-Zn(-Cu) alloyEutectic structureHigh strengthtiB2