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Zircon U-Pb-Hf constraints from Gongga Shan granites on young crustal melting in eastern Tibet 预览
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作者 Nick M.W. Roberts Michael P. Searle 《地学前缘:英文版》 CAS CSCD 2019年第3期885-894,共10页
The Gongga Shan batholith is a complex granitoid batholith on the eastern margin of the Tibetan Plateau with a long history of magmatism spanning from the Triassic to the Pliocene. Late MioceneePliocene units are the ... The Gongga Shan batholith is a complex granitoid batholith on the eastern margin of the Tibetan Plateau with a long history of magmatism spanning from the Triassic to the Pliocene. Late MioceneePliocene units are the youngest exposed crustal melts within the entire Asian plate of the Tibetan Plateau. Here, we present in-situ zircon Hf isotope constraints on their magmatic source, to aid the understanding of how these young melts were formed and how they were exhumed to the surface. Hf isotope signatures of Eocene to Pliocene zircon rims ( 3 Hf(t)=-4 to t4), interpreted to have grown during localised crustal melting, are indicative of melting of a Neoproterozoic source region, equivalent to the nearby exposed Kangding Complex. Therefore, we suggest that Neoproterozoic crust underlies this region of the Songpan eGanze terrane, and sourced the intrusive granites that form the Gongga Shan batholith. Localised young melting of Neoproterozoic lower or middle crust requires localised melt-fertile lithologies. We suggest that such melts may be equivalent to seismic and magnetotelluric low-velocity and high-conductivity zones or “bright spots” imaged across much of the Tibetan Plateau. The lack of widespread exposed melts this age is due either to the lack of melt-fertile rocks in the middle crust, the very low erosion level of the Tibetan plateau, or to a lack of mechanism for exhuming such melts. For Gongga Shan, where some melting is younger than nearby thermochronological ages of low temperature cooling, the exact process and timing of exhumation remains enigmatic, but their location away from the Xianshuihe fault precludes the fault acting as a conduit for the young melts. We suggest that underthrusting of dry granulites of the lower Indian crust (Archaean shield) this far northeast is a plausible mechanism to explain the uplift and exhumation of the eastern Tibetan Plateau. 展开更多
关键词 Tibet HIMALAYA HF ISOTOPES ZIRCON CRUSTAL melting
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Influence of Al/Cu content on grain boundary diffusion in Nd-Fe-B magnet via in-situ observation
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作者 Xinghua Cheng Jian Li +3 位作者 Lei Zhou Tao Liu Xiaojun Yu Bo Li 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第4期398-403,共6页
The influence of aluminum and copper content in the starting Nd-Fe-B magnet on grain boundary diffusion process(GBDP) was studied by observing the phase transformation behaviors of the magnets in-situ at high temperat... The influence of aluminum and copper content in the starting Nd-Fe-B magnet on grain boundary diffusion process(GBDP) was studied by observing the phase transformation behaviors of the magnets in-situ at high temperature. A higher coercivity increment is discovered in the sample with higher AI/Cu despite the fact that its Dy diffusion amount is the same as the other. DSC analysis shows an evident melting behavior in the higher Al/Cu sample. Laser scanning confocal microscopy(LSCM) in-situ characterization shows a large amount of melted intergranular phase spills out to the surface simultaneously at around 600 ℃ in the high Al/Cu sample, while the phase spills out gradually one after another in the range between 623 and680 ℃ in the other sample, which indicates that the intergranular phase can be more easily melted in the sample containing more AI/Cu. The area fraction of matrix phase remarkably shrinks while that of intergranular phase enlarges after LSCM heating, which demonstrates the outer region of the Nd2 Fe14B grains melt at the temperature of 900 ℃. Electron probe microanalyzer result(EPMA) shows that the Nd and Dy concentrate in edge regions and subsequently mix into the intergranular phase with the melting of the grain edge, while a large amount of AI and Cu in the intergranular phase spill out. Nevertheless, the sample with higher starting AI/Cu still remains higher residual contents after LSCM experiments, and that could probably be the main reason why the high AI/Cu magnet shows smaller coercivity decrement after LSCM experiment. Overall, the increase of AI/Cu in the starting magnet optimizes the Dy distribution and the wettability of intergranular phase, enhancing coercivity increment effect further. 展开更多
关键词 ND-FE-B sintered MAGNET Grain boundary diffusion process IN-SITU LSCM MELTING behavior Copper Aluminum
Phosphorus migration mechanism between iron and high phosphorus gangue phase at high temperatures
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作者 Lei Guo Jin-tao Gao +1 位作者 Sheng-ping Zhong Zhan-cheng Guo 《钢铁研究学报:英文版》 SCIE EI CAS CSCD 2019年第2期113-122,共10页
The phosphorus migration mechanism during melting separation of non-carbon-reduced high phosphorus iron ore was investigated.Firstly,the equilibrium compositions of hydrogen-reduced high phosphorus iron ore at differe... The phosphorus migration mechanism during melting separation of non-carbon-reduced high phosphorus iron ore was investigated.Firstly,the equilibrium compositions of hydrogen-reduced high phosphorus iron ore at different temperatures were simulated by the use of equilibrium composition module of HSC Chemistry software.Then,thermodynamic calculation was verified by the real heat treatment of simulated hydrogen-reduced high phosphorus iron ore with several pure reagents including self-made pure fluorapatite.The iron particles in the simulated samples gathered and grew up during heat treatment.Meanwhile,the hypoeutectic structure of Fe-P with grid shape of high phosphorus phase and circular shape of low phosphorus phase emerged within those iron particles.With the penetration of phosphorus from the periphery into the iron particles,the grid structure became denser and denser.It proves that the elemenlal phosphorus can be reduced from the gangue phase by metallic iron without solid carbon at high temperatures. 展开更多
关键词 MELTING separation FLUORAPATITE THERMODYNAMICS PHOSPHORUS migration High PHOSPHORUS IRON ore
飞秒激光制瓣LASIK增效术后上皮植入伴有角膜融解一例
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作者 张媛 韩浩 +2 位作者 贾冰冰 张岩 庞玉珍 《中华眼外伤职业眼病杂志》 2019年第3期237-238,共2页
飞秒激光制瓣LASIK术因具有较高的安全性,较好的预测性和较少的并发症,已经成为主流手术方式之一。飞秒激光制瓣LASIK术减少了角膜板层刀所带来的弥漫性层间角膜炎、角膜上皮植入和角膜融解等并发症。我院自2010年7月至2018年7月,共手术... 飞秒激光制瓣LASIK术因具有较高的安全性,较好的预测性和较少的并发症,已经成为主流手术方式之一。飞秒激光制瓣LASIK术减少了角膜板层刀所带来的弥漫性层间角膜炎、角膜上皮植入和角膜融解等并发症。我院自2010年7月至2018年7月,共手术近2万例,增效手术43例,只有1例发生上皮植入伴有角膜融解,经治疗,患者病情稳定,报告如下。 展开更多
关键词 LASIK 增效 上皮植入 角膜融解
抗冲共聚聚丙烯的结构与性能 预览
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作者 王帆 刘小燕 +2 位作者 周玲 朱博超 王晶晶 《合成树脂及塑料》 CAS 北大核心 2019年第1期58-62,68共6页
研究了5种熔体流动速率为28 g/10 min,乙烯质量分数为10%左右的车用抗冲共聚聚丙烯(IPC)的力学性能、相态结构、熔融结晶行为、橡胶相尺寸及分布、加工性能。结果表明:IPC-4整体力学性能最优,拉伸强度为24.60 MPa,弯曲模量为1 401.71 M... 研究了5种熔体流动速率为28 g/10 min,乙烯质量分数为10%左右的车用抗冲共聚聚丙烯(IPC)的力学性能、相态结构、熔融结晶行为、橡胶相尺寸及分布、加工性能。结果表明:IPC-4整体力学性能最优,拉伸强度为24.60 MPa,弯曲模量为1 401.71 MPa,冲击强度为10.02 kJ/m2;IPC是由无规共聚物、嵌段共聚物和均聚聚丙烯三部分组成;IPC-4具有最高的熔融焓和结晶焓,即材料有高的结晶度和刚性;IPC-4的孔洞分布更均匀、孔洞直径相差不大,平均值为1μm;5种试样的加工性能较为接近,最适宜的注塑温度为200℃。 展开更多
关键词 抗冲共聚聚丙烯 无规共聚物 熔融 结晶 流变性能 非等温动力学
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石墨烯增强钛基复合材料制备工艺与性能研究 预览
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作者 孙峰 王凯旋 +3 位作者 杨辉 史一功 杨晶 楼美琪 《钛工业进展》 CAS 北大核心 2019年第1期8-12,共5页
以多层石墨烯为增强体,通过熔炼锻造(MF)和粉末冶金(PM) 2种工艺分别制备出规格为Φ10 mm的石墨烯增强钛基复合材料棒材。石墨烯在凝固过程中以TiC枝晶形态析出,变形后呈细小颗粒,其中Ti和C原子比约为2∶1。石墨烯和球形钛粉经过机械合... 以多层石墨烯为增强体,通过熔炼锻造(MF)和粉末冶金(PM) 2种工艺分别制备出规格为Φ10 mm的石墨烯增强钛基复合材料棒材。石墨烯在凝固过程中以TiC枝晶形态析出,变形后呈细小颗粒,其中Ti和C原子比约为2∶1。石墨烯和球形钛粉经过机械合金化和变形加工,在基体中反应形成薄片层。MF工艺对应的棒材拉伸强度可达476 MPa,延伸率保持在28%;PM工艺对应的棒材拉伸强度可达487 MPa,延伸率保持在30%。PM工艺可形成尺寸较小的薄片状石墨烯增强体,强化作用提升,同时塑性没有显著下降。 展开更多
关键词 钛基复合材料 熔炼 粉末冶金 TIC 石墨烯
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Factors influencing power consumption and power-saving measures in ESR process
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作者 Yun-Long Xiong Zhao-Wei Song +1 位作者 An-Guo Wang Yan-Chun Lou 《中国铸造:英文版》 SCIE 2019年第1期1-7,共7页
Since the USA patent of electroslag remelting(ESR)metallurgy was held by P.K.Hopkins in 1940,the ESR technology has now entered a relatively mature stage after a 70-year history of development.At present,the annual ca... Since the USA patent of electroslag remelting(ESR)metallurgy was held by P.K.Hopkins in 1940,the ESR technology has now entered a relatively mature stage after a 70-year history of development.At present,the annual capacity of ESR steels around the world is approximately 2 million tonnes.ESR metallurgy emerged in China in 1958.Since then,electroslag furnaces were gradually installed in Chinese special steel plants.At present,there are more than 200 electroslag remelting furnaces in the metallurgical workshops of these steel plants with an annual production capacity of about 500,000 tonnes of ingots and components made of about 200 varieties of steels,including high quality steels and superalloys.This ESR technology is used as a special remelting and refining method for producing high quality steels and superalloys.However,traditional ESR technology has the disadvantages of environmental pollution and extremely high specific power consumption.High power consumption restricts,to a certain degree,the competitiveness of ESR steels in the marketplace.The measures of power saving in ESR have been researched in recent years.In this paper,some factors influencing power consumption,such as filling ratio,slag system,slag amount,melting rate and furnace structure are reviewed,and several new ESR technologies for power saving are proposed. 展开更多
关键词 ESR power SAVING FILL ratio SLAG system SLAG AMOUNT MELTING rate
YBCO高温超导带材熔融行为研究 预览
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作者 徐一鲡 赵睿鹏 +1 位作者 苟继涛 陶伯万 《电子元件与材料》 CAS CSCD 北大核心 2019年第6期50-55,共6页
对于第二代高温超导带材,超导接头的实现与超导层的直接熔融互连有关。为了研究YBa2Cu3O7-x(YBCO)高温超导带材在热处理时的熔融行为,在真空下对一段梯形的YBCO带材通电使其形成不同的温区,通过不同的测试手段研究薄膜经过热处理后成分... 对于第二代高温超导带材,超导接头的实现与超导层的直接熔融互连有关。为了研究YBa2Cu3O7-x(YBCO)高温超导带材在热处理时的熔融行为,在真空下对一段梯形的YBCO带材通电使其形成不同的温区,通过不同的测试手段研究薄膜经过热处理后成分、结构以及超导性能的变化。结果表明YBCO超导层在经过一个合适的温度和4h的氧气退火处理后,能够恢复或部分恢复其超导性能。经分析认为此过程中超导薄膜能够恢复超导性能的原因是Y123相没有分解。但是,如果热处理温度过高会导致Y123相分解为Y211相和钡铜氧化物,这种相变会导致超导性能无法恢复。 展开更多
关键词 YBCO 高温超导带材 热处理 熔融
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A novel polymer critical re-melting treatment for improving corrosion resistance of magnesium alloy stent
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作者 Shanshan Chen Peng Wan +3 位作者 Bingchun Zhang Deniz Eren Erisen Hui Yang Ke Yang 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第1期19-22,共4页
Polymer coating was widely used as a protective coating on Mg alloy stent due to its excellent deformability. However, the polymer coating with lots of macro-and micro-holes after solvent evaporation during forming pr... Polymer coating was widely used as a protective coating on Mg alloy stent due to its excellent deformability. However, the polymer coating with lots of macro-and micro-holes after solvent evaporation during forming process would make corrosion medium permeate easier and decrease the corrosion resistance of Mg alloy stent. In this study, a novel critical re-melting method was adopted to improve the polymer coating densification, which was evaluated by the surface morphology of coating. The corrosion resistance of Mg alloy stent after critical re-melting treatment was examined by the electrochemical and immersion tests. The results indicated that the corrosion resistance of Mg alloy stent with polymer coating was improved significantly by polymer critical re-melting treatment. 展开更多
关键词 Mg alloy STENT POLYMER coating CRITICAL re-melting treatment Corrosion resistance
高锌压铸ADC12ZS合金性能的研究
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作者 杨兴国 《特种铸造及有色合金》 CAS 北大核心 2019年第1期38-41,共4页
针对目前的再生铝行业需求,旨在研究一种Zn含量不高于2.5%的ADC12ZS铝合金。通过分析,相比于ADC12合金,ADC12ZS高温热脆性趋势增加,热裂倾向更大;熔炼过程中烧损严重,铝液耗损率大。铝锭制备时通过控制Zn元素的组织形式可以避免压铸的... 针对目前的再生铝行业需求,旨在研究一种Zn含量不高于2.5%的ADC12ZS铝合金。通过分析,相比于ADC12合金,ADC12ZS高温热脆性趋势增加,热裂倾向更大;熔炼过程中烧损严重,铝液耗损率大。铝锭制备时通过控制Zn元素的组织形式可以避免压铸的高温热脆性。严格控制炉料清洁度、比面积和除渣剂用量,适当提高加热速度,缩短熔炼时间,控制好炉内O2浓度,有利于降低铝液烧损率以及含渣量。 展开更多
关键词 铝合金 热脆性 烧损 含渣量 熔炼
镁合金压铸生产过程中的质量控制 预览
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作者 张艺钟 《世界有色金属》 2019年第9期168-169,共2页
镁合金的应用范围非常广,为了提升镁合金的质量,需要在对压铸质量进行严格控制。本文首先介绍了镁合金锭融化前的准备,随后阐述了镁合金压铸生产过程中的质量控制,以期对提升镁合金压铸质量有一定参考作用。
关键词 镁合金压铸 融化 质量控制
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相对分子质量对聚丙烯结晶和熔融行为的影响 预览
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作者 邹发生 宋文波 +1 位作者 张晓萌 刘振杰 《石油化工》 CAS CSCD 北大核心 2019年第4期357-361,共5页
在中试装置上合成了一系列相对分子质量不同但相对分子质量分布相似的均聚聚丙烯。利用 GPC,MFR,SAXS,DSC 等方法考察了相对分子质量对聚丙烯晶体结构、结晶和熔融行为的影响。表征结果显示,相对分子质量越大,聚丙烯注塑样条的片晶越容... 在中试装置上合成了一系列相对分子质量不同但相对分子质量分布相似的均聚聚丙烯。利用 GPC,MFR,SAXS,DSC 等方法考察了相对分子质量对聚丙烯晶体结构、结晶和熔融行为的影响。表征结果显示,相对分子质量越大,聚丙烯注塑样条的片晶越容易沿剪切方向取向,且其片晶厚度和非晶层厚度也越大。随着相对分子质量下降,聚丙烯的结晶温度和熔融温度降低,而结晶度增大。等规聚丙烯的平衡熔点为 188.2 ℃。 展开更多
关键词 相对分子质量 聚丙烯 结晶 熔融
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Strategies for creating living, add lively manufactured, open-cellular metal and alloy implants by promoting osseointegration, osteoinduction and vascularization;An overview
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作者 Lawrence E. Murr 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期231-241,共11页
Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assur... Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assuring elastic (Young's) modulus matching of proximate bone, along with corresponding pore sizes assuring osseointegration and vasculature development and migration.In addition, associated, requisite compressive and fatigue strengths for such implants are described. Strategies for optimizing osteoblast (bone cell) development and osteoinduction as well as vascularization of tissue in 3D scaffolds and tissue engineering constructs for bone repair are reviewed in relation to the biology of osteogenesis and neovascularization in bone, and the role of associated growth factors, bone morphogenic proteins, signaling molecules and the like. Prospects for infusing hydrogel/collagen matrices containing these cellular and protein components or surgically extracted intramedullary (bone marrow) concentrate/aspirate containing these biological and cell components into porous implants are discussed, as strategies for creating living implants, which over the long term would act as metal or alloy scaffolds. 展开更多
关键词 Additive manufacturing Open cellular metal and alloy IMPLANTS Electron beam melting LIVING implant STRATEGIES VASCULARIZATION OSSEOINTEGRATION OSTEOINDUCTION
Progress in additive manufacturing on new materials;A review
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作者 Neng Li Shuai Huang +5 位作者 Guodong Zhang Renyao Qin Wei Liu Huaping Xiong Gongqi Shi Jon Blackburn 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期242-269,共28页
Recent efforts and advances in additive manufacturing (AM) on different types of new materials are presented and reviewed. Special attention is paid to the material design of cladding layers, the choice of feedstock m... Recent efforts and advances in additive manufacturing (AM) on different types of new materials are presented and reviewed. Special attention is paid to the material design of cladding layers, the choice of feedstock materials, the metallurgical behavior and synthesis principle during the AM process, and the resulted microstructures and properties, as well as the relationship between these factors. Thereafter, the trend of development in the future is forecasted, including: Effects of the particles size and size distribution of powders;Approaches for producing fine microstructures;Opportunities for creating new materials by AM;Wide applications in reconditioning of damaged components;Challenges for deep understanding and applications of the AMed new materials. The idea of "Develop Materials" or "Create Materials" by AM is highlighted, but a series of scientific, technological and engineering problems remain to be solved in future. 展开更多
关键词 ADDITIVE MANUFACTURING FEEDSTOCK material Laser and electron BEAM MELTING Microstructure Property
A review of selective laser melting of aluminum alloys;Processing,microstructure, property and developing trends
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作者 Jinliang Zhang Bo Song +2 位作者 Qingsong Wei Dave Bourell Yusheng Shi 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期270-284,共15页
Selective laser melting(SLM) is an attractive rapid prototyping technology for the fabrication of metallic components with complex structure and high performance. Aluminum alloy, one of the most pervasive structural m... Selective laser melting(SLM) is an attractive rapid prototyping technology for the fabrication of metallic components with complex structure and high performance. Aluminum alloy, one of the most pervasive structural materials, is well known for high specific strength and good corrosion resistance. But the poor laser formability of aluminum alloy restricts its application. There are problems such as limited processable materials, immature process conditions and metallurgical defects on SLM processing aluminum alloys. Some efforts have been made to solve the above problems. This paper discusses the current research status both related to the scientific understanding and technology applications. The paper begins with a brief introduction of basic concepts of aluminum alloys and technology characterization of laser selective melting. In addition, solidification theory of SLM process and formation mechanism of metallurgical defects are discussed. Then, the current research status of microstructure, properties and heat treatment of SLM processing aluminum alloys is systematically reviewed respectively. Lastly, a future outlook is given at the end of this review paper. 展开更多
关键词 SELECTIVE laser MELTING Aluminum alloy Metallurgical DEFECTS Mechanical properties Heat treatment DEVELOPING TREND
Effect of ultrasonic vibration-assisted laser surface melting and texturing of Ti-6Al-4V ELI alloy on surface properties
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作者 Sourabh Biswas S. Habib Alavi +2 位作者 Bhishma Sedai Frank D. Blum Sandip P. Harimkar 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期295-302,共8页
Ultrasonic vibration-assisted laser surface processing that involves application of vertical ultrasonic vibrations to the Ti-6 Al-4 V alloy substrates while being irradiated with a CO2 laser was performed for the deve... Ultrasonic vibration-assisted laser surface processing that involves application of vertical ultrasonic vibrations to the Ti-6 Al-4 V alloy substrates while being irradiated with a CO2 laser was performed for the development of laser melted and textured surfaces with potential applications in biomedical implants.The laser processing resulted in very consistent repeating undulating grooved surfaces, and the undulations were significantly more pronounced in the samples processed with higher ultrasonic power outputs.The phase evolution, studied by x-ray diffraction, confirmed that the laser processing triggered transformation of globular α→ acicular α and martensitic α’ as well as increased amounts of retained α phases,which were also reflected in the microscopic analysis. The surface texture developed by laser processing resulted in increased surface wettability with increasing ultrasonic power output. The textured surfaces exhibited marked decrease in coefficients of friction during sliding wear testing performed under simulated body fluid due to lubricant entrainment within the textured grooves. The texturing also resulted in significant reduction in surface contact area during the wear process, which considerably reduced the overall wear rates due to abrasive wear. 展开更多
关键词 LASER TEXTURING LASER MELTING ULTRASONIC vibrations WEAR
Hierarchical microstructures with high spatial frequency laser induced periodic surface structures possessing different orientations created by femtosecond laser ablation of silicon in liquids 预览
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作者 Dongshi Zhang Koji Sugioka 《光电进展(英文)》 2019年第3期1-18,共18页
High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or micro... High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles. 展开更多
关键词 HIGH spatial frequency LASER induced periodic SURFACE structures SILICON LASER ablation in liquids HIERARCHICAL MICROSTRUCTURES femtosecond LASER HIGH fluence formation mechanism SURFACE melting nanocapillary wave SURFACE plasmon polaritons second-harmonic generation
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Recycled oceanic crust as a source for tonalite intrusions in the mantle section of the Khor Fakkan block, Semail ophiolite (UAE) 预览
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作者 Hosung Joun Sotirios Kokkalas Stylianos Tombros 《地学前缘:英文版》 CAS CSCD 2019年第3期1187-1210,共24页
Several types of felsic granitoid rocks have been recognized, intrusive in both the mantle and the crustal sequence of the Semail ophiolite. Several models have been proposed for the source of this suite of tonalites,... Several types of felsic granitoid rocks have been recognized, intrusive in both the mantle and the crustal sequence of the Semail ophiolite. Several models have been proposed for the source of this suite of tonalites, granodiorites, trondhjemites intrusions, however their genesis is still not clearly understood. The sampled Dadnah tonalites that intruded in the mantle section of the Semail ophiolite display arctype geochemical characteristics, are high siliceous, low-potassic, metaluminous to weakly peraluminous, enriched in LILE, show positive peaks for Ba, Pb, Eu, negative troughs for U, Ti and occur with low δ^18OH2O, moderate εSr and negative εNd values. They have crystallized at temperatures that range from ~550 ℃ to ~720 ℃ and pressure ranging from 4.4 kbar to 6.5 kbar. The isotopic ages from our tonalite samples range between 98.6 Ma and 94.9 Ma, slightly older and overlapping with the age of the metamorphic sole. Our field observations, mineralogical, petrological, geochemical, isotopic and melt inclusion data suggest that the Dadnah tonalites formed by partial melting (~10%-15% continuous or ~12% batch partial melting), accumulation of plagioclase, fractional crystallization (~55%-57%), and interaction with their host harzburgites. These tonalites were the end result of partial melting and subsequent contamination and mixing of w4% oceanic sediments with ~96% oceanic lithosphere from the subducted slab. This MORB-type slab melt composed from ~97% recycled oceanic crust and ~3% of the overlying mantle. We suggest that a possible protolith for these tonalites was the basaltic lavas from the subducted oceanic slab that melted during the initial stages of the supra-subduction zone (SSZ), which was forming synchronously to the spreading ridge axis. The tonalite melts mildly modified due to low degree of mixing and interaction with the overlying lithospheric mantle. Subsequently, the Dadnah tonalites emplaced at the upper part of the mantle sequence of the Semail ophiolite and are geochemically distinct 展开更多
关键词 Tonalites Felsic GRANITOIDS Recycled oceanic crust SOURCE contribution Partial melting Melt inclusions
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-60℃水平圆管表面结霜特性的实验研究 预览
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作者 任政 张兴群 +4 位作者 张蓓乐 薛绒 陈小砖 赖天伟 侯予 《西安交通大学学报》 EI CAS CSCD 北大核心 2019年第7期78-83,135共7页
为了探索在-60℃以下较低温区冷表面的结霜特性,设计并搭建了基于复叠制冷系统的-60℃水平圆管表面结霜特性可视化实验台,并对套管形式换热器内水平圆管外表面上湿空气顺掠管的结霜特性进行了实验研究,着重分析了结霜过程中霜层厚度及... 为了探索在-60℃以下较低温区冷表面的结霜特性,设计并搭建了基于复叠制冷系统的-60℃水平圆管表面结霜特性可视化实验台,并对套管形式换热器内水平圆管外表面上湿空气顺掠管的结霜特性进行了实验研究,着重分析了结霜过程中霜层厚度及其增长速率的特性。实验结果表明:-60℃水平圆管表面霜层厚度生长速率比常温区冷表面更快,约为-15℃冷表面的两倍,同时又保持了与-15℃以上冷表面相似的生长趋势,即前期生长速率较快,然后逐渐降低。此外,还发现并分析了呈周期性出现的融霜现象和大幅突降的霜层崩塌回融两种不同特征的融霜过程。初步探索了受限通道内-60℃水平圆管表面的结霜特性,丰富了霜层特性研究数据,可为今后更加全面系统的实验研究奠定基础。 展开更多
关键词 通道结霜 水平圆管 增长速率 霜层回融
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Impact of residual zircon on Nd-Hf isotope decoupling during sediment recycling in subduction zone 预览
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作者 Chen Zhang M.Santosh +3 位作者 Qun Luo Shu Jiang Luofu Liu Dongdong Liu 《地学前缘:英文版》 CAS CSCD 2019年第1期241-251,共11页
The subduction factories in convergent plate margins exert crucial control on recycling terrestrial components and returning to the overlying crust.The Nd and Hf isotopic systems provide potential tracers to evaluate ... The subduction factories in convergent plate margins exert crucial control on recycling terrestrial components and returning to the overlying crust.The Nd and Hf isotopic systems provide potential tracers to evaluate these processes.Here we present a case where these isotopic systems are decoupled in a suite of granites from the Chinese Altai,showing a wide range ofεHf(t)values(from-4.7 to+10.8)in contrast to a limited range ofεNd(t)values(from-5.8 to-1.9).The zircon xenocrysts occurring frequently in these rocks show markedly negativeεHf(t)values(from-34.3 to-6.5)and positiveδ^7Li values(from+12.5 to+18.2).We propose a model to explain the observed relationship between residual zircon and Nd-Hf isotope decoupling.We suggest that the Altai granites originated from partial melting of subducted slab components under relatively low temperature conditions which aided the residual zircon from oceanic sediments to inherit and retain a significant amount of 177Hf in the source,thereby elevating the 176Hf/177Hf ratio of the melt,and decoupling from the 143Nd/144Nd ratio during the subsequent magmatic processes.Our study illustrates a case where sediment recycling in subduction zone contributes to decoupling of Nd and Hf isotopic systems,with former providing a more reliable estimate of the source characteristics of granitic magmas. 展开更多
关键词 ND and Hf isotope SYSTEMATICS SUBDUCTION tectonics Oceanic SEDIMENT melting Geochemical RECYCLING Chinese ALTAI
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