检索结果-南通市图书馆

Effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on tensile and bending properties of high-Al-containing Mg alloys

引用

Journal of Magnesium and Alloys 2024年第2期12卷 779-793页

作者： Sumi Jo Gyo Myeong Lee Jong Un Lee young min kim Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Magnesium Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on the uniaxial tensile and three-point bending properties of extruded Mg alloys containing high Al contents.The extruded Mg–9Al–1Zn–0.3Mn(AZ91)alloy contains lamellar-structured Mg_(17)Al_(12)discontinuous precipitates along the grain boundaries,which are formed via static precipitation during natural air cooling.The extruded Mg–11Al–1Zn–0.3Mn(AZ111)alloy contains spherical Mg_(17)Al_(12)precipitates at the grain boundaries and inside the grains,which are formed via dynamic precipitation during extrusion.Due to inhomogeneous distribution of precipitates,the AZ111 alloy consists of two different precipitate regions:precipitate-rich region with numerous precipitates and finer grains and precipitate-scarce region with a few precipitates and coarser grains.The AZ111 alloy exhibits a higher tensile strength than the AZ91 alloy because its smaller grain size and more abundant precipitates result in stronger grain-boundary hardening and precipitation hardening effects,respectively.However,the tensile elongation of the AZ111 alloy is lower than that of the AZ91 alloy because the weak cohesion between the dynamic precipitates and the matrix facilitates the crack initiation and propagation.During bending,a macrocrack initiates on the outer surface of bending specimen in both alloys.The AZ111 alloy exhibits higher bending yield strength and lower failure bending strain than the AZ91 alloy.The bending specimens of the AZ91 alloy have similar bending formability,whereas those of the AZ111 alloy exhibit considerable differences in bending formability and crack propagation behavior,depending on the distribution and number density of precipitates in the specimen.In bending specimens of the AZ111 alloy,it is found that the failure bending strain(ε_(f,bending))is inversely proportional to the area fraction of precipitates in the outer zone of bending specimen(A_(ppt)),with a relationship ofε_(f,bending)=–0.1A_(ppt)+5.86.

关键词： Mg–Al alloy Extrusion Bending Precipitation Microstructure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chemical and mechanical properties of stainless, environment-friendly, and nonflammable Mg alloys (SEN alloys): A review

引用

Journal of Magnesium and Alloys 2024年第3期12卷 841-872页

作者： Jong Un Lee Hyun Ji kim Sang-Cheol Jin Ye Jin kim young min kim Bong Sun You Jun Ho Bae Sung Hyuk Park Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Missile Research Institute Agency for Defense DevelopmentDaejeon 34060Republic of Korea

This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials Science.SEN alloys are produced by adding small amounts of Ca and Y(eachminor amounts of Ca and Y renders excellent mechanical properties due to improved strengthening effects.These enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion.(4)Despite the presence of various types of second-phase particles,the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys.(5)Simultaneous introduction of Ca and Y suppresses the formation of Mg17Al12 discontinuous precipitates during aging,leading to the enhanced elongation of aged SEN alloys.(6)Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in extrudability.Consequently,the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties,which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.

关键词： SEN magnesium alloy Corrosion resistance Ignition resistance Mechanical properties Extrudability.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Microstructural characteristics and low-cycle fatigue properties of AZ91 and AZ91-Ca-Y alloys extruded at different temperatures

引用

Journal of Magnesium and Alloys 2023年第3期11卷 892-902页

作者： Ye Jin kim young min kim Jun Ho Bae Soo-Hyun Joo Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Dankook UniversityCheonan 31116Republic of Korea

The commercial AZ91 alloy and nonflammable SEN9(AZ91-0.3Ca-0.2Y,wt%)alloy are extruded at 300°C and 400°C.Their microstructure,tensile and compressive properties,and low-cycle fatigue(LCF)properties are investigated,with particular focus on the influence of the extrusion temperature.In the AZ91 and SEN9 materials extruded at 300°C(300-materials),numerous fine Mg_(17)Al_(12)particles are inhomogeneously distributed owing to localized dynamic precipitation during extrusion,unlike those extruded at 400°C(400-materials).These fine particles suppress the coarsening of recrystallized grains,decreasing the average grain size of 300-materials.Although the four extruded materials have considerably different microstructures,the difference in their tensile yield strengths is insignificant because strong grain-boundary hardening and precipitation hardening effects in 300-materials are offset almost completely by a strong texture hardening effect in 400-materials.However,owing to their finer grains and weaker texture,300-materials have higher compressive yield strengths than400-materials.During the LCF tests,{10-12}twinning is activated at lower stresses in 400-materials than in 300-materials.Because the fatigue damage accumulated per cycle is smaller in 400-materials,they have longer fatigue lives than those of 300-materials.A fatigue life prediction model for the investigated materials is established on the basis of the relationship between the total strain energy density(ΔW_(t))and the number of cycles to fatigue failure(N_(f)),and it is expressed through a simple equation(ΔW_(t)=10·N_(f)-0.59).This model enables fatigue life prediction of both the investigated alloys regardless of the extrusion temperature and strain amplitude.

关键词： AZ91-Ca-Y Extrusion temperature Microstructure Low-cycle fatigue Fatigue life prediction model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Use of various MgO resources for high-purity Mg metal production through molten salt electrolysis and vacuum distillation

引用

Journal of Magnesium and Alloys 2023年第2期11卷 562-579页

作者： Hyeong-Jun Jeoung Tae-Hyuk Lee youngjae kim Jin-young Lee young min kim Toru HOkabe Kyung-Woo Yi Jungshin Kang Korea Institute of Geoscience and mineral Resources 124 Gwahak-ro Yuseong-guDaejeon 34132South Korea Department of Materials Science and Engineering Seoul National University1 Gwanak-roGwanak-guSeoul 08826South Korea Department of Resources Engineering University of Science and Technology217 Gajeong-ro Yuseong-guDaejeon 34113South Korea Korea Institute of Materials Science 797 Changwondae-roSeongsan-guChangwonGyeongnam 51508South Korea Institute of Industrial Science The University of Tokyo4-6-1 KomabaMeguro-kuTokyo 153-8505Japan School of Materials Science and Engineering Pusan National University2 Busandaehak-roGeumjeong-guBusan 44241South Korea

A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing Mg O as a feedstock. The electrolysis of various Mg O resources was conducted using a Cu cathode in MgF2– LiF – KCl molten salt at 1043 K by applying an average current of 1.44 A for 12.5 h. The electrolysis of calcined North Korean magnesite and seawater Mg O clinker yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 89.6–92.4%. The electrolysis of oxidized Mg O-C refractory brick, aged ferronickel slag, and ferronickel slag yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 59.3–92.3%. The vacuum distillation of Mg alloys obtained was conducted at 1300 K for 10 h to produce high-purity Mg metal. After vacuum distillation, Mg metal with a purity of above 99.994% was obtained. Therefore, this study demonstrates the feasibility of the production of high-purity Mg metal from various Mg O resources using a novel electrolytic process with a Cu cathode, followed by vacuum distillation.

关键词： High-purity magnesium Magnesium oxide resources Electrolytic process Metal cathode Vacuum distillation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Variations in microstructure and bending formability of extruded Mg–Al–Zn–Ca–Y–MM alloy with precompression and subsequent annealing treatment conditions

引用

Journal of Magnesium and Alloys 2022年第9期10卷 2475-2490页

作者： Jong Un Lee Sang-Hoon kim Dong Hee Lee Hyun Ji kim young min kim Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Agency for Defense Development Daejeon 34186Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea

In this study, the bending formability of an extruded Mg–9Al–1Zn–0.3Mn–0.9Ca–0.6Y–0.5 MM(AZXWMM91100, wt%) alloy at room temperature is significantly improved through application of a combined precompression and subsequent annealing(PCA) treatment. As the amount of precompression applied along the extrusion direction(ED)(i.e., the total strain) increases from 4% to 6%, the area fraction of ED-oriented grains of the PCA-treated alloy increases, which consequently causes an improvement in its bending formability because these grains accommodate larger tensile strain along the ED during bending. As the temperature of the subsequent annealing treatment increases from 350 ℃ to 450 ℃, both the area fraction of the ED-oriented grains and the average grain size increase, and the residual dislocation density decreases owing to the promotion of boundary migration and occurrence of the recovery process at higher temperatures.Consequently, the bending formability of both the 4%-precompressed and the 6%-precompressed samples increases with an increase in the annealing temperature. However, when the precompressed samples are annealed at 300 ℃, their bending formability is lower than that of the extruded alloy because the dislocations formed by precompression remain even after the subsequent annealing at this temperature.

关键词： Magnesium Extrusion Bending Formability Texture

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Segmented tomographic evaluation of structural degradation of carbon support in proton exchange membrane fuel cells

引用

Journal of Energy Chemistry 2022年第11期31卷 359-367,I0010页

作者： Jung A.Hong min-Hyoung Jung Sung Yong Cho Eun-Byeol Park Daehee Yang young-Hoon kim Sang-Hyeok Yang Woo-Sung Jang Jae Hyuck Jang Hyo June Lee Sungchul Lee Hu young Jeong young-min kim Department of Energy Science Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Fuel Cell Core Parts Development Cell Hyundai Mobis Co.Ltd.Uiwang 16082Republic of Korea Electron Microscopy&Spectroscopy Team Korea Basic Science Institute(KBSI)Daejeon 34133Republic of Korea Graduate School of Semiconductor Materials and Devices Engineering Ulsan National Institute of Science and Technology(UNIST)Ulsan 44919Republic of Korea

The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the nanoscale.However,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus far.Therefore,a reliable methodology is required for the 3D geometrical evaluation of the carbon structure.Here,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high resolution.This approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D networking.These geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced degradation.This information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes.

关键词： Electron tomography Fuel cell Proton exchange membrane Membrane electrode assembly Carbon corrosion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Injectable polymeric nanoparticle hydrogel system for long-term anti-inflammatory effect to treat osteoarthritis

引用

Bioactive Materials 2022年第1期7卷 14-25页

作者： Bo-Bae Seo youngjoong Kwon Jun kim Ki Hyun Hong Sung-Eun kim Hae-Ryong Song young-min kim Soo-Chang Song Center for Biomaterials Korea Institute of Science&TechnologySeoul02792South Korea Division of Bio-Medical Science and Technology KIST SchoolKorea University of Science and TechnologySeoul02792South Korea Department of Orthopedic Surgery and Rare Diseases Institute Korea University Medical College Guro HospitalSeoul08308South Korea

Treatment of osteoarthritis(OA)by administration of corticosteroids is a commonly used method in clinics using anti-inflammatory medicine.Oral administration or intra-articular injection of corticosteroids can reduce the pain and progress of cartilage degeneration,but they are usually insufficient to show local and long-term anti-inflammatory effects because of their fast clearance in the body.In this study,we suggest an injectable anti-OA drug depot system for sustained drug release that provides long-term effective therapeutic advantages.Amphiphilic poly(organophosphazene),which has temperature-dependent nanoparticle forming and sol-gel transition behaviors when dissolved in aqueous solution,was synthesized for triamcinolone acetonide(TCA)delivery.Because hydrophobic parts of the polymer can interact with hydrophobic parts of the TCA,the TCA was encapsulated into the self-assembled polymeric nanoparticles.The TCA-encapsulated polymeric nanoparticles(TePNs)were well dispersed in an aqueous solution below room temperature so that they can be easily injected as a sol state into an intra-articular region.However,the TePNs solution transforms immediately to a viscose 3D hydrogel like a synovial fluid in the intra-articular region via the conducted body temperature.An in vitro TCA release study showed sustained TCA release for six weeks.One-time injection of the TePN hydrogel system in an early stage of OA-induced rat model showed a great inhibition effect against further OA progression.The OA-induced knees completely recovered as a healthy cartilage without any abnormal symptoms.

关键词： Thermosensitive hydrogel Triamcinolone acetonide Polymer nanoparticle Osteoarthritis Sustained release

来源：

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

Effects of Processing Parameters on Microstructure and Properties of Ultra High Strength Linepipe Steel

引用

Journal of Materials Science & Technology 2012年第10期28卷 889-894页

作者： Xiaodan Wu Hakcheol Lee young min kim Nack J.kim University of Pittsburgh Pittsburghl PA 15213USA Pohang University of Science and Technology Pohang 790-784Korea

To examine the effect of processing parameters on microstructural evolution and to obtain the excellent combination of strength and toughness, simulation of thermo-mechanical processing was conducted using the Gleeble machine. Trial production was then conducted under the conditions obtained by Gleeble tests. Based on the results of microstructure analysis and mechanical property evaluation, the relationship between microstructural features and mechanical properties was elucidated. The result shows that the volume fraction of constituted phases can be controlled through adjusting the cooling rate and finish cooling temperature in order to get different strength levels. As cooling rate increases, the volume fraction of upper bainite increases, which leads to the increase of strength. The upper shelf energy （USE） increases with increasing volume fraction of acicular ferrite in bainite base because of the small effective acicular ferrite grain size. Ductile-brittle transition temperature （DBTT） decreases with increasing acicular ferrite volume fraction. High reduction in the rough stage has great influence on grain refinement.

关键词： Linepipe steel Microstructure Gleeble test TMCP （thermomechanicalcontrol process）

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Microstructural evolution and grain growth mechanism of pre-twinned magnesium alloy during annealing

引用

Journal of Magnesium and Alloys 2021年第4期9卷 1238-1251页

作者： Ye Jin kim Jong Un Lee young min kim Sung Hyuk Par School of Materials Science and Engineering Kyungpook National JJniversityDaegu 41566Republic of Korea Implementation Research Division Korea Institute of Materials ScienceChanson 51508Republic of Korea

The microstructural evolution and underlying grain growth mechanism of a{1012}-twin-containing Mg alloy during annealing are investigated through quasi in situ electron backscatter diffraction measurements of a rolled AZ31 alloy subjected to precompression along the rolling direction(RD).The precompressed material shows a partially twinned structure consisting of a twinned region and a residual matrix region,and this structure changes to an almost twin-free structure consisting of grown grains with serrated grain boundaries in twinand matrix-originated regions after annealing at 250℃ for 1 h.In addition,the average grain size almost doubles and the internal strain energy decreases significantly after annealing.These microstructural variations are induced mainly by grain growth through the strain-induced migration of high-angle grain boundaries without the movement of twin boundaries.The twinned region of the precompressed material has higher stored strain energy than the residual matrix region because the crystallographic orientation of the former region is favorable for basal slip and because of the occurrence of the dislocation transmutation reaction in the twins.For reducing the total strain energy accumulated in the precompressed material,the residual matrix region—having lower stored strain energy—preferentially grows while consuming the twinned regions formed in the surrounding grains during annealing.As a result,the area fraction of grains with a matrix texture increases whereas that of grains with a twin texture decreases after annealing.The twin texture intensity increases significantly and this texture becomes more concentrated along the RD because the highly RD oriented twins tend to grow during annealing on account of their fairly low stored strain energy.

关键词： Magnesium Twin Annealing Grain growth Strain energy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Development of a novel electrolytic process for producing high-purity magnesium metal from magnesium oxide using a liquid tin cathode

引用

Journal of Magnesium and Alloys 2021年第5期9卷 1661-1672页

作者： Tae-Hyuk Lee Toru H.Okabe Jin-young Lee young min kim Jungshin Kang Korea Institute of Geoscience and mineral Resources 124 Gwahak-ro Yuseong-guDaejeon 34132Republic of Korea Institute of Industrial Science The University of Tokyo4-6-1 KomabaMeguro-kuTokyo 153-8505Japan University of Science and Technology 217 Gajeong-ro Yuseong-guDaejeon 34113Republic of Korea Korea Institute of Materials Science 797 Changwondae-roSeongsan-guChangwonGyeongnam51508Republic of Korea

The current electrolytic processes for magnesium(Mg)metal have several disadvantages,such as anhydrous magnesium chloride(MgCl_(2))preparation and generation of harmful chlorine(Cl_(2))gas.To overcome these drawbacks,a novel Mg production process to produce high-purity Mg metal directly from magnesium oxide(MgO)was investigated in this study.The electrolysis of MgO was conducted using a liquid tin(Sn)cathode and a carbon(C)anode in the eutectic composition of a magnesium fluoride(MgF_(2))-lithium fluoride(LiF)molten salt under an applied voltage of 2.5 V at 1053-1113 K.Under certain conditions,the Mg-Sn alloys with Mg_(2)Sn and Mg(Sn)phases were obtained with a current efficiency of 86.6%at 1053 K.To produce high-purity Mg metal from the Mg-Sn alloy,vacuum distillation was conducted at 1200-1300 K for a duration of 5-10 h.Following the vacuum distillation,the concentration of Mg in the Mg-Sn alloy feed decreased from 34.1 to 0.17 mass%,and Mg metal with a purity of 99.999%was obtained at 1200 K.Therefore,the electrolytic process developed here is feasible for the production of high-purity Mg metal from MgO using an efficient method.

关键词： Magnesium Magnesium oxide Electrolytic process Liquid tin cathode Vacuum distillation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：