检索结果-南通市图书馆

Effect of high magnetic fields on the solidification microstructure of an Al-Mn alloy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2009年第3期28卷 302-308页

作者： LUO Dawei GUO Jin YAN Zhiming li tingju School of Materials Science and Engineering Dalian University of Technology Dalian 116023 China State Key Laboratory of Materials Modification by Laser Ion and Electron Beams Dalian 116023 China

The effect of high magnetic fields on the morphology of Al-Mn phases was investigated. It is found that the tropism and the alignment of Al6Mn precipitated phases become regular under high magnetic fields. The stronger the high magnetic fields, the more regular the alignment of Al6Mn precipitated phases. Al6Mn precipitated phases can generate oriented alignment and aggregation under high magnetic fields through the observation of the quenched microstructure of the Al-Mn alloy at different temperatures. Meanwhile, the number of Al6Mn phases increases continuously along with the increasing function time of high magnetic fields. X-ray diffraction also indicates that Al6Mn phases generate obvious tropism under high magnetic fields. The process of aggregation and growth of Al6Mn precipitated phases under the function of high magnetic fields after orientation were analyzed and discussed.

关键词： high magnetic fields Al-Mn alloy Al-Mn phase orientation

Crystal orientation and corrosion resistance of CuNi10Fe1Mn alloy billet under rotating electromagnetic field

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2012年第6期31卷 552-555页

作者： Fu Yabo Cui Jing li tingju Taizhou Univ Sch Phys & Elect Engn Taizhou 318000 Peoples R China Civil Aviat Univ China Sch Airport Tianjin 300300 Peoples R China Dalian Univ Technol Sch Mat Sci & Engn Dalian 116024 Peoples R China

CuNi10Fe1Mn alloy billet under rotating electromagnetic field (REF) was characterized in this work. The change of the crystal orientation was first explored by X-ray diffraction (XRD) and scanning election microscope (SEM); the corrosion resistance was done by three electrodes system, and the natural sea water was used as corrosion medium. The results demonstrate that the strongest crystal orientation is transformed from crystal plane (200) to (111); moreover, the crystal plane (111) whose intensity is the strongest on the cross section and vertical section with REF causes the tubes be rolled easily, and the corrosion resistance of the billet is increasing with REF. As a result, properties of CuNi10Fe1Mn alloy tubes can be improved by REF.

关键词： rotating electromagnetic field (REF) crystal orientation corrosion resistance

Microstructure and Mechanical Properties of a CoFeNi_2V_(0.5)Nb_(0.75) Eutectic High Entropy Alloy in As-cast and Heat-treated Conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2016年第3期32卷 245-250页

作者： li Jiang Yiping Lu Wei Wu Zhiqiang Cao tingju li School of Materials Science and Engineering Dalian University of Technology State Key Laboratory of Metastable Materials Science and Technology Yanshan University

The eutectic CoFeNi2V0.5Nb0.75 high entropy alloys （HEAs） were heated at 500, 600, 700, 800 and 1000 ℃, respectively for 6 h and subsequently quenched in the water to investigate their thermal stability and phase transformation at high temperature. The microstructure and mechanical properties of the samples were investigated by scanning electron microscopy, X-ray diffraction, compressive and hardness tests. It was found that the as-cast CoFeNi2V0.5Nb0.75 HEAs showed a eutectic microstructure with alternating fcc solid solution phase and Fe2Nb-type Laves phase. The NbNi4-type intermetallic phase appeared when the heat-treated temperature was higher than 600 ℃. With increasing quenching temperature, the volume fraction of the NbNi4-type intermetallic phase increased while that of the eutectic regions decreased. The sample quenched at 800 ℃ showed the most excellent comprehensive mechanical properties; its fracture strength, yield strength and plastic strain were as high as 2586.76 MPa, 2075.18 MPa and 16.73%, respectively. Moreover, the eutectic CoFeNi2V0.5Nb0.75 HEAs exhibited apparent age hardening, especially quenched at 700 ℃, the hardness reached up to the maximum value of HV 727.52.

关键词： High entropy alloy Microstructure Thermal stability Age hardening

Effect of carbon addition on the microstructure and mechanical properties of CoCrFeNi high entropy alloy

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2018年第1期61卷 117-123页

作者： HUANG TianDang JIANG li ZHANG Changliang JIANG Hui LU YiPing li tingju Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University ofTechnologv Dalian 116024 China School of Mechanical Engineering. Dalian University of Technology Dalian 116024 China

The effects of C element on the microstructure and properties of CoCrFeNiC,. high entropy alloys （x denoted the atomic fraction of C element at 0, 0.05, 0.1, 0.2, 0.3, and 0.5） were investigated. The equal molar CoCrFeNi alloy with FCC structure exhibits high ductility but weak strength. With the addition of C element, both the hardness and strength of the CoCrFeNiCx high entropy alloys increase as well as the wear resistance. The solution strengthening and the lbrmation of hard carbide phase are the main thctor for the improved strength, hardness and wear resistance of CoCrFeNiC~ high entropy alloys.

关键词： high entropy alloys carbon mechanical properties wear resistance

Mechanical Properties Improvement of AlCrFeNi_2Ti_(0.5) High Entropy Alloy through Annealing Design and its Relationship with its Particle-reinforced Microstructures

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2015年第4期31卷 397-402页

作者： li Jiang Hui Jiang Yiping Lu Tongmin Wang Zhiqiang Cao tingju li School of Materials Science and Engineering Dalian University of Technology

High entropy alloy has attracted increasing ***,to enhance the alloy strength often leads to impairment of the ductility,or vice *** we reported a heat treatment approach on AlCrFeNi2Ti0.5 high entropy alloy,which can elevate the strength and ductility *** ingot of AlCrFeNi2Ti0.5 weighing 2.5 kg was firstly fabricated by medium frequency induction *** samples from the same height of the bulk ingot were annealed for 6 h at 600,700,800 and 1000 ℃,*** 1000 ℃ annealing,an optimal microstructure was obtained by using our approach which can make some precipitation particles distribute homogeneously in the dendrite interior while keep the interdendrite structure as a single solid solution *** mechanical test on this AlCrFeNi2Ti0.5 alloy sample showed that,the compressive fracture strength σbc was increased by about600 MPa and the plastic strain ep was doubled,compared with those of the as-cast *** approach can be readily adapted to large-scale industrial production of high entropy alloys with high strength and ductility by proper annealing treatment.

关键词： High entropy alloy Heat treatment Microstructure M

A novel as-cast precipitation-strengthened Al_(0.5)V_(0.1)FeCrMnNi_(0.9) high-entropy alloy with high strength and plasticity

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2021年第9期64卷 1920-1926页

作者： li ChunHui WANG Mingliang ZHANG HuanZhi ZHANG GuoJia li TianXin LU YiPing li tingju Key Laboratory of Solidification Control and Digital Preparation Technology(liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China

A novel Al_(0.5)V_(0.1)FeCrMnNi_(0.9) high-entropy alloy was designed to achieve enhanced strength and plasticity. The as-cast Al_(0.5)V_(0.1)FeCrMnNi_(0.9) alloy shows a typical dendritic microstructure consisting of a body-centered cubic-structured matrix phase and a B2-structured nanoprecipitate phase. Nanoprecipitates are homogeneous and dispersed in the matrix. The as-cast Al_(0.5)V_(0.1)FeCrMnNi_(0.9) alloy exhibits a compressive yield strength of 1.104 GPa, a fracture strength of 2.926 GPa, and a fracture strain of 45.7%. The product of strength and plasticity of this alloy is 133.72 GPa%, which is superior to that of most of the reported high-entropy alloys. The strengthening mechanisms were evaluated in detail, which indicates that the coherent precipitation enhancement contributes to the unusually high strength and plasticity.

关键词： high-entropy alloy microstructure mechanical properties precipitation strengthening

Study of ultrahigh-purity copper billets refined by vacuum melting and directional solidification

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2011年第3期30卷 304-309页

作者： FU Yabo CHEN Jie liU Ning LU Yiping li tingju YIN Guomao Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education Dalian University of Technology Dalian 116085 China School of Materials Science and Engineering Dalian University of Technology Dalian 116085 China

The purpose of this paper is to study large-sized copper billets refined with 5N ultrahigh purity after vacuum melting and directional solidifi-cation （VMDS）. The precise impurity analysis of copper billets was carried out with a glow discharge mass spectrometer （GDMS）. The re-sults demonstrate that the total concentration of twenty-two impurities is decreased by 63.1wt.%-66.5 wt.%. Ag, P, S, Na, Mg, Se, Zn, In and Bi are easy to be removed due to lgPimp - lgPCu 1.5, and they can be removed effectively under the vacuum condition of 1650-1700 K for 30 min. The electrical conductivity of 5N copper is higher than that of the raw material as the impurity concentrations decrease. The segrega-tion effect in directional solidification can be remarkable when the equilibrium distribution coefficient （k0） value is less than 0.65 due to the strong affinity of Cu for some metallic and non-metallic impurities.

关键词： copper refining vacuum melting directional solidification electrical conductivity

Effect of Niobium on Microstructure and Properties of the CoCrFeNb_xNi High Entropy Alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第7期33卷 712-717页

作者： Hui Jiang li Jiang Dongxu Qiao Yiping Lu Tongmin Wang Zhiqiang Cao tingju li Key Laboratory of Solidification Control and Digital Preparation Technology （liaoning Province） School of Materials Science and Engineering Dalian University of Technology Dalian 116024. China

A series of CoCrFeNb_xNi（x values in molar ratio, x = 0, 0.25, 0.45, 0.5, 0.75, 1.0 and 1.2） high entropy alloys（HEAs） was prepared to investigate the alloying effect of Nb on the microstructures and mechanical properties. The results indicate that the prepared CoCrFeNb_xNi（x 〉 0） HEAs consist of a simple FCC solid solution phase and a Laves phase. The microstructures of the alloys change from an initial single-phase FCC solid solution structure（x = 0） to a hypoeutectic microstructure（x = 0.25）, then to a full eutectic microstructure（x = 0.45） and finally to a hypereutectic microstructure（0.5 〈 x 〈 1.2）. The compressive test results show that the Nb0.45（x = 0.45） alloy with a full eutectic microstructure possesses the highest compressive fracture strength of 2558 MPa and a fracture strain of 27.9%. The CoCrFeNi alloy exhibits an excellent compressive ductility, which can reach 50% height reduction without fracture. The Nb0.25 alloy with a hypoeutectic structure exhibits a larger plastic strain of 34.8%. With the increase of Nb content, increased hard/brittle Laves phase leads to a decrease of the plasticity and increases of the Vickers hardness and the wear resistance. The wear mass loss, width and depth of wear scar of the Nb1.2（x = 1.2） alloy with a hypereutectic structure are the lowest among all alloy systems, indicating that the wear resistance of the Nb1.2 alloy is the best one.

关键词： Alloy design Microstructure Mechanical properties Wear resistance

Growth mechanism of primary Ti_(5)Si_(3) phases in special brasses and their effect on wear resistance

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第2期61卷 138-146页

作者： Xianlong Wang Jinchuan Jie Shichao liu Zhuangzhuang Dong Guomao Yin tingju li Key Laboratory of Solidification Control and Digital Preparation Technology(liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian116024China

In the present work, in-situ Ti_(5)Si_(3) reinforced special brasses were prepared by melt reaction method. The synthesized Ti_(5)Si_(3) phase shows various morphologies in brasses with different Ti_(5)Si_(3) content, and the3 D morphological evolution of primary Ti_(5)Si_(3)and its growth mechanism were investigated. The Ti_(5)Si_(3) crystal, which bears D8_(8) hexagonal crystal structure, grows along direction and is revealed by{1010} faces during growth. With the increase of Ti_(5)Si_(3) content in the brasses, the morphology of primary Ti_(5)Si_(3)significantly changes from fibers to hexagonal prisms to short-rods with hollow. In addition,the influence of Ti_(5)Si_(3) volume fraction and morphology on the wear behavior of special brass was also revealed. It was substantiated that the wear resistance increases with the increasing volume fraction of Ti_(5)Si_(3), and the corresponding wear mechanism changes from delamination to slight adhesive wear and abrasive wear. However, the friction coefficient shows an abnormal increase when most of the Ti_(5)Si_(3) containing hollows appears in the brass. That is mainly due to the fact that the Ti_(5)Si_(3) is easier to break and fall off resulted by the hollow as a crack source, which makes it unable to resist the plastic deformation of the contact surface during the sliding.

关键词： Ti_(5)Si_(3) Brass Morphology Growth mechanism Wear behavior