期刊文献+
共找到11,268篇文章
< 1 2 250 >
每页显示 20 50 100
基于CTA颅内动脉瘤形态联合PHASES评分对破裂出血预测研究
1
作者 王金泉 黄吉淮 谢颖 《影像研究与医学应用》 2024年第4期31-34,共4页
目的:分析头颈部计算机断层扫描血管成像(CTA)联合PHASES评分对颅内动脉瘤(IA)破裂出血的预测价值。方法:回顾性分析2021年10月—2023年9月东莞市长安医院诊治的IA患者临床资料,根据IA破裂出血与否分为IA破裂组(n=46)和IA未破裂组(n=44)... 目的:分析头颈部计算机断层扫描血管成像(CTA)联合PHASES评分对颅内动脉瘤(IA)破裂出血的预测价值。方法:回顾性分析2021年10月—2023年9月东莞市长安医院诊治的IA患者临床资料,根据IA破裂出血与否分为IA破裂组(n=46)和IA未破裂组(n=44),收集两组临床资料,对比两组患者CTA影像瘤体特征参数和PHASES评分结果。采用受试者工作特征(ROC)曲线分析两者联合预测动脉瘤破裂的效能。结果:IA破裂组高血压、糖尿病发生率及PHASES评分均高于IA未破裂组,差异有统计学意义(P <0.05)。两组病灶位置以颈内动脉(ICA)和大脑中动脉(MCA)为主,但IA破裂组病灶位置在MCA的占比为41.30%,高于IA未破裂组的20.45%,瘤体>7 mm的最多(瘤体7~9.9 mm占65.22%),瘤体形态不规则占58.7%,未破裂组病灶位置在ICA最多(68.18%),瘤体<7 mm的居多(75.00%),瘤体形态规则囊状动脉瘤占93.18%,差异有统计学意义(P <0.05)。CTA瘤体特征参数比较,IA破裂组患者瘤颈宽度、瘤体高度、瘤体长度、动脉瘤最大直径、入射夹角、动脉瘤体颈比等参数均高于IA未破裂组,差异有统计学意义(P <0.05)。CTA瘤体特征参数+PHASES评分联合预测曲线下面积为0.916,高于CTA瘤体特征参数(0.901)和PHASES评分(0.731)。结论:CTA瘤体特征参数+PHASES评分联合预测IA患者破裂出血效能最佳。 展开更多
关键词 颅内动脉瘤 破裂出血 CTA phases评分
下载PDF
Effect of ultrasonic and mechanical vibration treatments on evolution of Mn-rich phases and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys
2
作者 Bo LIN Xiang-xiang HE +3 位作者 Song-chao XIA Hua-qiang XIAO Yu-liang ZHAO Khashayar KHANLARI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2024年第8期2393-2414,共22页
Effects of ultrasonic vibration(UV)and mechanical vibration(MV)on the Mn-rich phase modification and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys were investigated.The results show that the UV and UV... Effects of ultrasonic vibration(UV)and mechanical vibration(MV)on the Mn-rich phase modification and mechanical properties of Al−12Si−4Cu−1Ni−1Mg−2Mn piston alloys were investigated.The results show that the UV and UV+MV treatments can significantly refine and fragmentize the microstructures.In addition,UV treatment can significantly passivate the primary Mn-rich Al15Mn3Si2 intermetallics.The formation mechanisms of refinement and passivation of the grains and non-dendrite particles were discussed.Compared with the gravity die-cast alloys,the UV and UV+MV treated alloys exhibit improved tensile and creep resistance at room and elevated temperatures.These results can be attributed to the refinement of theα(Al)grains and the secondary intermetallics,the increased proportion of refined heat-resistant precipitates,and the formation of nano-sized Si particles.The ultimate tensile strength of the UV treated alloys at 350℃ exceeds that of commercial piston alloys.This indicates the high application potential of the developed piston alloys in density diesel engines. 展开更多
关键词 Al−Si piston alloys Mn-rich phases mechanical properties ultrasonic vibration mechanical vibration
下载PDF
Effect of thermo-mechanical conditions during constrained friction processing on the particle refinement of AM50 Mg-alloy phases
3
作者 Camila Caroline de Castro AndréMartins Neves Benjamin Klusemann 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第6期2298-2311,共14页
Constrained Friction Processing(CFP)is a novel solid-state processing technique suitable for lightweight materials,such Mg-and Al-alloys.The technique enables grain size refinement to fine or even ultrafine scale.In t... Constrained Friction Processing(CFP)is a novel solid-state processing technique suitable for lightweight materials,such Mg-and Al-alloys.The technique enables grain size refinement to fine or even ultrafine scale.In this study,the effect of CFP on the microstructural refinement of AM50 rods is investigated in terms of particle size and morphology of the eutectic and secondary phases originally present in the base material,in particular the eutecticβ-Mg_(17)Al_(12)and Al-Mn phases.For that purpose,as-cast and solution heat-treated base material and processed samples were analyzed.The Al_(8)Mn_(5) intermetallic phase was identified as the main secondary phase present in all samples before and after the processing.A notorious refinement of these particles was observed,starting from particles with an average equivalent length of a few micrometers to around 560 nm after the processing.The refinement of the secondary phase refinement is attributed to a mechanism analogous to the attrition comminution,where the combination of temperature increase and shearing of the material enables the continuous breaking of the brittle intermetallic particles into smaller pieces.As for the eutectic phase,the results indicate the presence of the partially divorcedβ-Mg_(17)Al_(12)particles exclusively in the as-cast base material,indicating that no further phase transformations regarding the eutectic phase,such as dynamic precipitation,occurred after the CFP.In the case of the processed as-cast material analyzed after the CFP,the thermal energy generated during the processing led to temperature values above the solvus limit of the eutectic phase,which associated with the mechanical breakage of the particles,enabled the complete dissolution of this phase.Therefore,CFP was successfully demonstrated to promote an extensive microstructure refinement in multiple aspects,in terms of grain sizes of theα-Mg phase and presence and morphology of the Al-Mn and eutecticβ-Mg_(17)Al_(12). 展开更多
关键词 Constrained friction processing AM50 Refill friction stir spot welding Extrusion β-Mg_(17)Al_(12) Al-Mn phases
下载PDF
The effect of Laves phases and nano-precipitates on the electrochemical corrosion resistance of Mg-Al-Ca alloys under alkaline conditions
4
作者 Markus Felten Veronika Chaineux +12 位作者 Siyuan Zhang Ali Tehranchi Tilmann Hickel Christina Scheu Joshua Spille Marta Lipińska-Chwałek Joachim Mayer Benjamin Berkels Marcus Hans Imke Greving Silja Flenner Sandra Sefa Daniela Zander 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第6期2447-2461,共15页
The electrochemical corrosion mechanisms of Mg alloys were extensively studied in previous investigations of different chemical com-positions,modified surface states and various electrolyte conditions.However,recent r... The electrochemical corrosion mechanisms of Mg alloys were extensively studied in previous investigations of different chemical com-positions,modified surface states and various electrolyte conditions.However,recent research focused on the active state of Mg dissolution,leading to unresolved effects of secondary phases adjacent to a stableα-solid solution passive layer.The present study investigates the fundamental electrochemical corrosion mechanisms of three different Laves phases with varying phase morphologies and phase fractions in the passive state of Mg-Al-Ca alloys.The microstructure was characterized by(transmission-)electron microscopy and synchrotron-based transmission X-ray microscopy.The electrochemical corrosion resistance was determined with a standard three-electrode setup and advanced in-situ flow cell measurements.A new electrochemical activity sequence(C15>C36>α-Mg>C14)was obtained,as a result of a stable passive layer formation on theα-solid solution.Furthermore,nm-scale Mg-rich precipitates were identified within the Laves phases,which tend to inhibit the corrosion kinetics. 展开更多
关键词 Laves phase STEM MAGNESIUM Corrosion Passive layer
下载PDF
The occurrence phases and enrichment mechanism of rare earth elements in cobalt-rich crusts from Marcus-Wake Seamounts
5
作者 Jingjing Gao Jihua Liu +3 位作者 Hui Zhang Shijuan Yan Xiangwen Ren Quanshu Yan 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第8期58-68,共11页
To explore the occurrence phases and enrichment mechanism of rare earth elements(REEs)in cobalt-rich crusts,this study analyzes the mineral composition and REE contents of the samples from Marcus-Wake Seamounts by XRD... To explore the occurrence phases and enrichment mechanism of rare earth elements(REEs)in cobalt-rich crusts,this study analyzes the mineral composition and REE contents of the samples from Marcus-Wake Seamounts by XRD,ICP-OES and ICP-MS.The results show that,(1)the cobalt-rich crusts contain the major crystalline mineral(vernadite),the secondary minerals(quartz,plagioclase and carbonate fluorapatite),and a large amount of amorphous ferric oxyhydroxides(FeOOH).(2)The cobalt-rich crusts contains higher Mn(10.83%to 28.76%)and Fe(6.14%to 18.86%)relative to other elements,and are enriched in REEs,with total REE contents of 1563−3238μg/g and Ce contents of 790−1722μg/g.Rare earth element contents of the old crusts are higher than those of the new crusts.Moreover,the non-phosphatized crusts have positive Ce and negative Y anomalies,and yet the phosphatized crusts have positive Ce and positive Y anomalies,indicating that cobalt-rich crusts is hydrogenetic and REEs mainly come from seawater.(3)Analytical data also show that the occurrence phases of elements in cobalt-rich crusts are closely related to their mineral phases.In the non-phosphatized crusts,REEs are adsorbed by colloidal particles into the crusts(about 67%of REEs in the Fe oxide phase,and about 17%of REEs in the Mn oxide phase).In contrast,in the phosphatized crusts(affected by the phosphatization),REEs may combine with phosphate to form rare earth phosphate minerals,and about 64%of REEs are enriched in the residual phase containing carbonate fluorapatite,but correspondingly the influence of Fe and Mn oxide phases on REEs enrichment is greatly reduced.In addition,the oxidizing environment of seawater,high marine productivity,phosphatization,and slow growth rate can promote the REE enrichment.This study provides a reference for the metallogenesis of cobalt-rich crusts in the Pacific. 展开更多
关键词 cobalt-rich crusts REEs occurrence phase enrichment mechanism Marcus-Wake Seamounts
下载PDF
Topological phases and edge modes of an uneven ladder
6
作者 商文创 韩熠宁 +1 位作者 Shimpei Endo 高超 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期154-168,共15页
We investigate the topological properties of a two-chain quantum ladder with uneven legs,i.e.,the two chains differ in their periods by a factor of 2.Such an uneven ladder presents rich band structures classified by t... We investigate the topological properties of a two-chain quantum ladder with uneven legs,i.e.,the two chains differ in their periods by a factor of 2.Such an uneven ladder presents rich band structures classified by the closure of either direct or indirect bandgaps.It also provides opportunities to explore fundamental concepts concerning band topology and edge modes,including the difference of intracellular and intercellular Zak phases,and the role of the inversion symmetry(IS).We calculate the Zak phases of the two kinds and find excellent agreement with the dipole moment and extra charge accumulation.We also find that configurations with IS feature a pair of degenerate two-side edge modes emerging as the closure of the direct bandgap,while configurations without IS feature one-side edge modes emerging as not only the closure of both direct and indirect bandgaps but also within the band continuum.Furthermore,by projecting to the two sublattices,we find that the effective Bloch Hamiltonian corresponds to that of a generalized Su–Schrieffer–Heeger model or the Rice–Mele model whose hopping amplitudes depend on the quasimomentum.In this way,the topological phases can be efficiently extracted through winding numbers.We propose that uneven ladders can be realized by spin-dependent optical lattices and their rich topological characteristics can be examined by near future experiments. 展开更多
关键词 ladder model symmetry-protected topological phase topological invariant bulk-boundary correspondence
下载PDF
Stress-corrosion coupled damage localization induced by secondary phases in bio-degradable Mg alloys:phase-field modeling
7
作者 Chao Xie Shijie Bai +2 位作者 Xiao Liu Minghua Zhang Jianke Du 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2024年第1期361-383,共23页
In this study,a phase-field scheme that rigorously obeys conservation laws and irreversible thermodynamics is developed for modeling stress-corrosion coupled damage(SCCD).The coupling constitutive relationships of the... In this study,a phase-field scheme that rigorously obeys conservation laws and irreversible thermodynamics is developed for modeling stress-corrosion coupled damage(SCCD).The coupling constitutive relationships of the deformation,phase-field damage,mass transfer,and electrostatic field are derived from the entropy inequality.The SCCD localization induced by secondary phases in Mg is numerically simulated using the implicit iterative algorithm of the self-defined finite elements.The quantitative evaluation of the SCCD of a C-ring is in good agreement with the experimental results.To capture the damage localization,a micro-galvanic corrosion domain is defined,and the buffering effect on charge migration is explored.Three cases are investigated to reveal the effect of localization on corrosion acceleration and provide guidance for the design for resistance to SCCD at the crystal scale. 展开更多
关键词 Phase field Mg alloys Stress-corrosion coupled damage Damage localization Finite element method
下载PDF
The Spatiotemporal Distribution Characteristics of Cloud Types and Phases in the Arctic Based on CloudSat and CALIPSO Cloud Classification Products
8
作者 Yue SUN Huiling YANG +5 位作者 Hui XIAO Liang FENG Wei CHENG Libo ZHOU Weixi SHU Jingzhe SUN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2024年第2期310-324,共15页
The cloud type product 2B-CLDCLASS-LIDAR based on CloudSat and CALIPSO from June 2006 to May 2017 is used to examine the temporal and spatial distribution characteristics and interannual variability of eight cloud typ... The cloud type product 2B-CLDCLASS-LIDAR based on CloudSat and CALIPSO from June 2006 to May 2017 is used to examine the temporal and spatial distribution characteristics and interannual variability of eight cloud types(high cloud, altostratus, altocumulus, stratus, stratocumulus, cumulus, nimbostratus, and deep convection) and three phases(ice,mixed, and water) in the Arctic. Possible reasons for the observed interannual variability are also discussed. The main conclusions are as follows:(1) More water clouds occur on the Atlantic side, and more ice clouds occur over continents.(2)The average spatial and seasonal distributions of cloud types show three patterns: high clouds and most cumuliform clouds are concentrated in low-latitude locations and peak in summer;altostratus and nimbostratus are concentrated over and around continents and are less abundant in summer;stratocumulus and stratus are concentrated near the inner Arctic and peak during spring and autumn.(3) Regional averaged interannual frequencies of ice clouds and altostratus clouds significantly decrease, while those of water clouds, altocumulus, and cumulus clouds increase significantly.(4) Significant features of the linear trends of cloud frequencies are mainly located over ocean areas.(5) The monthly water cloud frequency anomalies are positively correlated with air temperature in most of the troposphere, while those for ice clouds are negatively correlated.(6) The decrease in altostratus clouds is associated with the weakening of the Arctic front due to Arctic warming, while increased water vapor transport into the Arctic and higher atmospheric instability lead to more cumulus and altocumulus clouds. 展开更多
关键词 CloudSat and CALIPSO cloud type cloud phase temporal and spatial distribution interannual variation
下载PDF
Solid-state NMR studies of proteins in condensed phases
9
作者 Jiani Xiang Xialian Wu +1 位作者 Angelo L.Chu Junxia Lu 《Magnetic Resonance Letters》 2024年第3期1-10,共10页
Some proteins perform their biological functions by changing their material states through liquid-liquid phase separation.Upon phase separation,the protein condenses into a concentrated liquid phase and sometimes into... Some proteins perform their biological functions by changing their material states through liquid-liquid phase separation.Upon phase separation,the protein condenses into a concentrated liquid phase and sometimes into a gel phase,changing its dynamic properties and intermolecular interactions,thereby regulating cellular functions.Although the biological significance of this phenomenon has been widely recognized by researchers,there is still a lack of a comprehensive understanding of the structural and dynamic properties of the protein in the condensed phase.In this phase,molecules usually contain domains with varied dynamic properties and undergo intermediate exchanges.Magic angle spinning(MAS)solid-state NMR(SSNMR)experiments are very powerful in studying rigid protein polymers such as amyloid.The incorporation of solution-like experiments into SSNMR and the development of J-coupling based MAS SSNMR techniques extend its ability to study partially mobile segments of proteins in a condensed liquid or gel phase which are not visible by solution NMR or dipolar-coupling based SSNMR.Therefore,it has been applied in studying protein condensation and has provided very important information that is hard to obtain by other techniques. 展开更多
关键词 Magic angle spinning(MAS)solid-state NMR(SSNMR) Protein condenses J-coupling based MAS SSNMR Liquid-liquid phase separation
下载PDF
Commensurate and incommensurate Haldane phases for a spin-1 bilinear-biquadratic model
10
作者 代艳伟 陈爱民 +1 位作者 刘希婧 苏耀恒 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第9期157-162,共6页
Commensurate and incommensurate Haldane phases for a spin-1 bilinear-biquadratic model are investigated using an infinite matrix product state algorithm.The bipartite entanglement entropy can detect a transition point... Commensurate and incommensurate Haldane phases for a spin-1 bilinear-biquadratic model are investigated using an infinite matrix product state algorithm.The bipartite entanglement entropy can detect a transition point between the two phases.In both phases,the entanglement spectrum shows double degeneracy.We calculate the nonlocal order parameter of the bond-centered inversion in both phases,which rapidly approaches a saturation value of-1 as the segment length increases.The nonlocal order parameter of the bond-centered inversion with a saturation value-1 and the nonzero value string order indicate that the Haldane phase is a symmetry-protected topological phase.To distinguish the commensurate and incommensurate Haldane phases,the transversal spin correlation and corresponding momentum distribution of the structure factor are analyzed.As a result,the transversal spin correlations exhibit different decay forms in both phases. 展开更多
关键词 commensurate and incommensurate phases symmetry-protected topological phase transversal spin correlation
下载PDF
Appraisal of Engineering Phases of a Mineral Asset: From Exploration to Mine Approval
11
作者 Edmundo Tulcanaza 《Journal of Minerals and Materials Characterization and Engineering》 CAS 2023年第3期69-79,共11页
It is well known that the most common methodology for evaluating a mineral asset is the NPV. Most of the mining companies employ this technique for evaluating the expected economic benefits provided by the exploration... It is well known that the most common methodology for evaluating a mineral asset is the NPV. Most of the mining companies employ this technique for evaluating the expected economic benefits provided by the exploration and exploitation of a mineral deposit. However, companies also wish to know how their assets are creating value through the several exploration and development phases. The purpose being to assess the progressive value of the mineral asset in agreement with the information and data cumulated through the different steps from exploration to project approval. This paper establishes the value of a copper mineral deposit through their successive phases from exploration to feasibility and approval using the options’ binomial nodes framework. Results are applied to two copper negotiations for method validation. 展开更多
关键词 Mine Value Exploration phases Binomial Nodes Copper Deposits Method Validation
下载PDF
Variable precipitation behaviors of Laves phases in an ultralight Mg-Li-Zn alloy 被引量:2
12
作者 Weixin Lou Hongbo Xie +7 位作者 Xiaobo Zhao Junyuan Bai Hehang Zhang Yi Wang Xinze Li Hucheng Pan Yuping Ren Gaowu Qin 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第6期2018-2026,共9页
Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a... Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a specific habit plane owing to the constraint of free-energy minimization of the system.Herein,in an aged ultralight Mg-Li-Zn alloy,we confirmed that the precipitates dominated by C15 Laves structure could form in a variety of habit planes,to generate three forms of strengthening-phases,i.e.,precipitate-rod,precipitate-lath,and precipitate-plate.Among which,the precipitate-plates are on basal plane as usually but precipitate-rods/laths are on non-basal plane,and such non-basal precipitates would transform into the basal(Mg,Li)Zn_(2)Laves structure with prolonged aging.These findings are interesting to understand the precipitation behaviors of multi-domain Laves structures in hexagonal close-packed crystals,and expected to provide a guidance for designing ultralight high-strength Mg-Li based alloys via precipitation hardening on the non-basal planes. 展开更多
关键词 Laves phase PRECIPITATION Habit plane ORIENTATION Magnesium alloys
下载PDF
Recent applications and chiral separation development based on stationary phases in open tubular capillary electrochromatography(2019–2022) 被引量:1
13
作者 Xinyu Li Qianjie Ma +2 位作者 Xiangtai Zheng Qin Chen Xiaodong Sun 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2023年第4期323-339,共17页
Capillary electrochromatography(CEC)plays a significant role in chiral separation via the double separation principle,partition coefficient difference between the two phases,and electroosmotic flow-driven separation.G... Capillary electrochromatography(CEC)plays a significant role in chiral separation via the double separation principle,partition coefficient difference between the two phases,and electroosmotic flow-driven separation.Given the distinct properties of the inner wall stationary phase(SP),the separation ability of each SP differs from one another.Particularly,it provides large room for promising applications of open tubular capillary electrochromatography(OT-CEC).We divided the OT-CEC SPs developed over the past four years into six types:ionic liquids,nanoparticle materials,microporous materials,biomaterials,non-nanopolymers,and others,to mainly introduce their characteristics in chiral drug separation.There also added a few classic SPs that occurred within ten years as supplements to enrich the features of each SP.Additionally,we discuss their applications in metabolomics,food,cosmetics,environment,and biology as analytes in addition to chiral drugs.OT-CEC plays an increasingly significant role in chiral separation and may promote the development of capillary electrophoresis(CE)combined with other instruments in recent years,such as CE with mass spectrometry(CE/MS)and CE with ultraviolet light detector(CE/UV). 展开更多
关键词 Capillary electrochromatography Open tubular capillary Chiral separation Stationary phase Capillary electrophoresis with mass spectrometry(CE/MS)
下载PDF
High-pressure new phases of V–N compounds
14
作者 时旭含 李志慧 +4 位作者 刘媛媛 王元元 刘冉 胡阔 姚震 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第5期560-565,共6页
The high-pressure diagram of V–N compounds is enriched by proposed seven new stable high-pressure phases.The P-1-VN_4with the armchair N-rich structure may be quenched to ambient conditions.The formed N–N covalent b... The high-pressure diagram of V–N compounds is enriched by proposed seven new stable high-pressure phases.The P-1-VN_4with the armchair N-rich structure may be quenched to ambient conditions.The formed N–N covalent bond plays an important role for the structural stability of N-chain.The charge transfer results in a V–N ionic bond interaction,which further improves the stability of N-chain structure.The P-1-VN_4,P4mnc-VN_8,and Immm-VN_(10)with the outstanding detonation properties have potential application in explosive field. 展开更多
关键词 high-pressure N-rich V–N compounds phase diagram STABILITY DFT calculation
下载PDF
Mechanical properties and electronic structures of MgCu_2, Mg_2Ca and MgZn_2 Laves phases by first principles calculations 被引量:6
15
作者 毛萍莉 于波 +2 位作者 刘正 王峰 鞠阳 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第9期2920-2929,共10页
Mechanical properties and electronic structure of MgCu2, Mg2 Ca and MgZn2 phases were investigated by means of first principles calculations from CASTEP program based on density functional theory(DFT). The calculate... Mechanical properties and electronic structure of MgCu2, Mg2 Ca and MgZn2 phases were investigated by means of first principles calculations from CASTEP program based on density functional theory(DFT). The calculated lattice parameters are in good agreement with the experimental and literature values. The calculated heat of formation and cohesive energies showed that MgCu2 has the strongest alloying ability and structural stability. Elastic constants of MgCu2, Mg2 Ca and MgZn2 were calculated, and the bulk moduli, shear moduli, elastic moduli and Poisson ratio were derived. The calculated results show that MgCu2, Mg2 Ca and MgZn2 are all ductile phases. Among the three phases, MgCu2 has the strongest stiffness and the plasticity of MgZn2 phase is the best. Melting points of the three phases were predicted using cohesive energy and elastic constants. Density of states(DOS), Mulliken population, electron occupation number and charge density difference were discussed. Finally, Debye temperature was calculated and discussed. 展开更多
关键词 magnesium alloy MgCu2 Mg2Ca MgZn2 Laves phases electronic structure mechanical property Debye temperature
下载PDF
Study on Fruit Quality, Phenological Phases and Shoot Histomorphology of a New Bud Mutant Line, ‘Chuanzao Loquat’ 被引量:5
16
作者 梅洛银 廖明安 +4 位作者 任雅君 刘雨 程籍 刘娟 罗丽 《Agricultural Science & Technology》 CAS 2012年第9期1881-1884,共4页
[Objective] This study was to explore the growth characteristics and fruit quality of a new bud mutant line, 'Chuanzao Loquat'. [Method] Paraffin section technique combined with field investigation method were adopt... [Objective] This study was to explore the growth characteristics and fruit quality of a new bud mutant line, 'Chuanzao Loquat'. [Method] Paraffin section technique combined with field investigation method were adopted to conduct com- parative analysis of shoot histomorphology and phenological phases between two Io- quat varieties, 'Chuanzao Loquat' and 'Zaozhong 6'. [Result] 'Chuanzao Loquat' branched out and unfolded leaves about half to a month earlier than 'Zaozhong 6'; both the flowering and fruiting phases of 'Chuanzao Loquat' were three months earlier than a precocious variety, 'Zaozhong 6'; the proportions of epidermis, cortex parenchyma, vascular tissue and medulla were 3.7%, 14.5%, 15.9% and 65.9%, re- spectively, in spdng shoots of 'Chuanzao Loquat', and 3.1%, 42.5%, 6.9% and 47.5%, respectively, in 'Zaozhong 6'. [Conclusion] In terms of phenological phases, 'Chuanzao Loqua' is earlier than 'Zaozhong 6', a currently widely planted precocious variety, and thus is an important germplasm resource of Ioquats. 展开更多
关键词 'Chuanzao Loquat' 'Zaozhong 6' Phenological phases HISTOMORPHOLOGY
下载PDF
Morphology development of elongated α phases in hot working of large-scale titanium alloy plate 被引量:3
17
作者 樊晓光 杨合 +1 位作者 高鹏飞 严思梁 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第12期3508-3516,共9页
The role of subtransus hot working on microstructure morphology of TA15 titanium alloy plate with elongatedαphases was studied by quantitative metallography on different sections. The results show that the microstruc... The role of subtransus hot working on microstructure morphology of TA15 titanium alloy plate with elongatedαphases was studied by quantitative metallography on different sections. The results show that the microstructure morphology is mainly affected by loading direction. When the sample is compressed along normal direction, microstructure on the section vertical to normal direction has equiaxed primaryαphase but microstructure on the section vertical to rolling direction has strip primaryαphase with long axis along tangential direction. When the sample is compressed along rolling direction, microstructure on the section vertical to normal direction has strip primaryαphase elongated along tangential direction but microstructure on the section vertical to rolling direction consists of strip and irregular broad-band primaryαphase. The strip primaryαphase aspect ratio is smaller at lower temperature due to the dynamic break-down ofαphase. The difference on primaryαphase aspect ratio between different sections decreases after compression along distinct directions in two loading passes, suggesting the improvement of equiaxity of primaryαphase. 展开更多
关键词 microstructure morphology TA15 titanium alloy elongatedαphases subtransus hot working
下载PDF
Modification Behavior of Trace Rare Earth on Impurity Phases in Commercial Purity Aluminum 被引量:27
18
作者 傅高升 孙锋山 +2 位作者 任立英 陈文哲 钱匡武 《Journal of Rare Earths》 SCIE EI CAS CSCD 2002年第1期61-66,共6页
Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an... Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction). 展开更多
关键词 rare earths commercial purity aluminum Fe rich impurity phases modification of impurity phases
下载PDF
Precipitation of metastable phases and its effect on electrical resistivity of Al-0.96Mg_2Si alloy during aging 被引量:3
19
作者 崔立新 刘振兴 +4 位作者 赵晓光 唐建国 刘科 刘星兴 钱晨 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第7期2266-2274,共9页
The precipitation behavior and its influence on the electrical resistivity of the Al-0.96Mg2Si alloy during aging were investigated with in-situ resistivity measurement and transmission electron microscopy (TEM). Th... The precipitation behavior and its influence on the electrical resistivity of the Al-0.96Mg2Si alloy during aging were investigated with in-situ resistivity measurement and transmission electron microscopy (TEM). The precipitates of the peak aged alloy include both β" and if, but the amount ratio of β" to β" varies with the aging temperature and time increasing. The precipitates during aging at 175 ℃ are dominated by needle-like β" phases (including pre-β" phase), the size of which increases with the time prolonging, but does not increase substantially after further aging. The evolution of electrical conductivity is directly related to such microstructural evolution. However, the hardness of the alloy stays at the peak value for a long term. When the alloy is aged at 195 ℃, the ratio of β" to β' becomes the main factor to influence relative resistivity (Ap) value. The higher the temperature is, the smaller the ratio is, and the faster the Ap value decreases. Moreover, the hardness peak drops with the decrease of the ratio. With the size and distribution parameters measured from TEM images, a semi-quantitative relationship between precipitates and the electrical resistivity was established. 展开更多
关键词 Al-Mg-Si alloy metastable phases electrical resistivity AGING PRECIPITATE
下载PDF
As-cast microstructure and Sr-containing phases of AZ31 magnesium alloys with high Sr contents 被引量:5
20
作者 吴璐 潘复生 +2 位作者 杨明波 吴菊英 刘婷婷 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第4期784-789,共6页
The as-cast microstructure and Sr-containing phases in the AZ31 magnesium alloys with different Sr contents (0%, 0.3%, 2.5% and 5.0%, mass fraction) were investigated. The results indicate that after adding Sr to th... The as-cast microstructure and Sr-containing phases in the AZ31 magnesium alloys with different Sr contents (0%, 0.3%, 2.5% and 5.0%, mass fraction) were investigated. The results indicate that after adding Sr to the AZ31 magnesium alloy, the dendrite/grain size is decreased, and with the Sr content increasing from 0 to 5.0%, the dendrite becomes finer, the dendrite morphology becomes more passive and the distribution of alloying phases at dendrite/grain boundary is dispersed. Furthermore, the morphology of the β-Mg 17 Al 12 phase in the alloy with addition of 0.3%Sr changes from continuously irregular strip-like shape to discontinuously irregular strip-like shape and/or fine granule-like shape. At the same time, some lamella-like eutectic phases are found in the alloys with additions of 2.5% Sr and 5.0% Sr, and the lamella spacing in the alloy with addition of 5.0% Sr is finer. Adding high Sr content to the AZ31 alloy can bring the new ternary eutectic and/or divorced eutectic phase of Mg 11 Al 5 Zn 4 in the alloy, and the Mg 17 Sr 2 and Mg 2 Sr phases are formed in the alloys with additions of 2.5% Sr and 5.0% Sr. 展开更多
关键词 magnesium alloy AZ31 magnesium alloy Sr-containing phase SR
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部