Papers by Author: Yan Li

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Authors: Yan Li, Jie Qi, Chuan Xin Zhai, Ran Feng Qiu
Abstract: The Ti-10Nb-5Sn alloy was heated and cooled repeatedly in a heater system located in transmission electron microscope chamber. The phase and morphology transformation was in situ observed to analyze the transformation mechanism from austenite β to martensite phase. The results reveal that he Ti-10Nb-5Sn alloy has round trip shape memory function.
Authors: Yan Li, Xiao Hong Chen, Ping Liu, Lin Hua Gao, Bao Hong Tian
Abstract: The behavior of plastic deformation of Cu-15Cr-0.1Zr in-situ composite under different degree of cold drawing deformation was analyzed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that both Cu and Cr phases are elongated along cold drawn direction and appear a fibrous morphology; However, Cu phase shows a thread-like fibrous morphology and Cr phase shows a band-like fibrous morphology. The two phases have a coherent relationship of (111)Cu //(011)Cr; When the degree of deformation(ε)is equal to 6.43, the relationship shows// [111]Cu // [110]Cr //cold drawn direction. Furthermore, forming two different morphologies of Cu and Cr phases during cold drawing is also analyzed.
Authors: Jing Liu, Yong Feng Dong, Yan Li, Si Yuan Lei, Shu Qun He
Abstract: For composite fault is difficult to diagnose, the characteristics of the large amount of data. This paper presents a method of The Prediction method of Composite Fault Based on data driven to establish intelligence unit Based on a collection of virtual individuals associated with the virtual failure associated collection and virtual behavior associated collection. Composite fault warning engine modeling is proposed, and give the warning value of composite fault finally. This method is fully assessing the future "dominant state" on the basis of the fully aware of current "hidden state". The impact of factors such as disturbance of hidden failures on composite fault prediction are fully considered, to some extent, the long-span composite failure prediction problem is solved, and the experiments show that the method effectively increases the accuracy of composite fault prediction.
Authors: Chuan Xin Zhai, Yan Li, Xin Yang Wang, Liu Jie Xu, Shi Zhong Wei
Abstract: The Fe-Based Al2O3-TiC Ceramic Composite was fabricated by combining the methods of Self-propagating High-temperature Synthesis with casting. The microstructures of ceramic layer and interface were characterized via SEM, EDS and X-ray diffraction. The Results show that the microstructure of ceramic layer is dense, and the in-situ Al2O3 and TiC particles with size of 1-2 μm are distributed on the ferrite matrix. The hardness of compact ceramic layer reaches 48HRC, and it has graded distribution from ceramic layer to the ferrite matrix. The composite interface between ceramic and matrix is compact, and takes on flexuous. The composite material bonds in a metallographic manner, with high bonding strength.
Authors: Yan Li, Shi Zhong Wei, Jian Ping Gao, Wan Hong Zhang, Rui Long
Abstract: Microstructure in anchoring site of TiC cermets/steel explosive cladding plate was analyzed by transmission electron microscope (TEM), scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS). An intermittent micro-crystal layer, with thickness of about 10μm, was observed in anchoring area. The inner crystal size was in range of some nanometer to hundreds of nanometer. The phases of the layer are mainly austenite, ferrite, and some titanium carbide. A flow layer was observed in the area near the steel side. The diffusion of Ti is the most apparent and the diffusion length is about 15μm. The observation of the microstructure in anchoring area revealed the nature of explosive compound in metallurgical anchoring.
Authors: Yan Li, Shi Zhong Wei, Liu Jie Xu, Chun Wei Xu, Rui Long
Abstract: The high-speed steel (HSS) reinforced by in-situ VC /35CrMo compound roll was produced by electromagnetic semicontinuous casting. The element distribution and the structure morphology of the interface were analysed, and the mechanical properties were tested. The results indicate that the thickness of diffusion layer is around 50μm. The microstructure of the diffusion layer is pearlite, and next to the diffusion layer, the microstructures are ferrite and pearlite at the alloyed steel side. There are in-situ VC particles in martensitic matrix. At the high-speed steel side. The microhardness of HSS and 35CrMo is about 700HV and 250HV, respectively, and that of diffusion layer is near 350HV, which is between that of HSS and 35CrMo. The impact toughness is 100 Jcm-2. On the basis of the experiment, the interface of compound roll prepared by electromagnetic semicontinuous casting obtains good microscopic structure and mechanical properties, which are the results of the metallurgically bonded interface.
Authors: Yan Li, Chuan Xin Zhai, Chun Hua Xu
Abstract: The AlMn and AlMnSi foils were fabricated by rapid solidification technology. The phase transformation temperatures, microstructures and distribution of elements were characterized by Differential Scanning Calorimetry (DSC), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD) and Energy Disperse Spectroscopy (EDS) respectively. The result shows that the phases of AlMn7 nanofoil conclude Al, Al6Mn and quasicrystal phase, the crystal size is about 120nm; the phases of AlMn5Si5 nanofoil conclude Al, Al4.01MnSi0.74 and Al9Mn3Si, the crystal size is about 60nm. The phase transformation temperatures of AlMn7 and AlMn5Si5 nanofoils are 543K and over 873K, respectively. The microstructure morphology of AlMn7 nanofoil are rod, block and petal-like, but the microstructure morphology of AlMn5Si5 nanofoil is homogeneous globular.
Authors: Shi Zhong Wei, Yan Li, Jian Ping Gao, Ying Ping Ji, Rui Long
Abstract: WC steel bond hard alloy powders were compacted by explosive compaction on the surface of carbon steel, then the composite layer was prepared by liquid-phase sintering in vacuum. The phases and microstructures of the interface of composite layer were observed by SEM, EDS, TEM. Result showed that the thickness of the interface was about 30μm, and the elements of W, Cr, C were detected in the interface. The structures of the interface were pearlites which were composed of the layered tablets of M23C6 and ferrite. The layered tablets were perpendicular to the interface. The structures were the pearlites and ferrites in the side of the carbon steel near the interface but globular carbides, whose phase is W3Fe3C, and pearlites in side of steel bond hard alloy. During sintering at 1623K, all elements of metal-powder and C, V, which were decomposed by hard-phase, interdiffused in the interface. The multiple carbides were found in the interface and steel bond hard alloy. As a result, the powders formed into compact alloy by itself, and at the same time there was a good metallurgical bonding between the carbon steel and the hard alloy.
Authors: Rui Rui Fan, Yan Li, Liu Jie Xu, Shi Zhong Wei
Abstract: Al2O3 reinforced iron based composite were prepared via in-situ synthesis with aluminum nitrate, citric acid and iron powder as raw materials, a little C and Mo as additive. The influences of the contents of Al2O3, C and Mo on the microstructure and micro-hardness of the Fe based composites were characterized by XRD, SEM, TEM and micro-hardness tester. The results showed that the Fe-based composite materials with high bonding strength between matrix and Al2O3 can be prepared by in situ synthesis method. The best ratio of the nine Al2O3 particles reinforced Fe-based composite materials in three groups is 3vol. % C, 5vol. % or 7vol. % Al2O3, sintering temperature is 1300°C and quenching temperature is 900°C. The microstructure of the matrix without C addition is ferrite before and after quenching; the microstructure of the matrix with C addition is pearlite before quenching, and the microstructure become to martensite after quenching, the α-Al2O3 and FeC3 are reinforced phases. The microstructure of the matrix with Mo addition is ferrite and FeAl2O4 before and after quenching.
Authors: Yan Li, Shi Zhong Wei, Rui Long
Abstract: The morphology and phase structure of Al/Cu explosive compounded interface were observed by scanning electron microscope, high-resolution transmission electron microscope and X-ray energy spectrometer. The results reveal that the interface of Al/Cu appears wave-like structure, with an average wavelength of 1.0mm and crest height of 0.3mm. Every wave has its front-nest. The wavelike interfaces are composed of microcrystal compound layer, non-crystal and nanocrystal. Several kinds of compounds such as Al9Cul2, Al4Cu9, Al2Cu, η-AlCu, β-AlCu3 and unidentified phase structure were found in Al/Cu interface. There are some bent lattice fringes around the front-nest. The research of microstructure in anchoring area revealed the nature of explosive cladding in metallurgical anchoring.
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