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Alloying effects of V on stability,elastic and electronic properties of TiFe2 via first-principles calculations

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Journal of Central South University 2017年第7期24卷 1551-1559页

作者： NONG Zhi-sheng CUI Pu-chang ZHU Jing-chuan ZHAO Rong-da School of Materials Science and Engineering Shenyang Aerospace UniversityShenyang 110136China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Liaoning University of TechnologyJinzhou 121001China

The alloying effects of V on structural,elastic and electronic properties of TiFe_2 phase were investigated by the first-principles calculations based on the density functional *** calculated energy properties including cohesive energy and formation enthalpy indicate V atom would preferentially substitute on 6h sites of Fe atoms in the lattice of TiFe_2 to form the intermetallic Ti_4Fe_7(V).The calculated results of polycrystalline elastic parameters confirm that the plasticity of TiFe_2 would be improved with the addition of *** discussing the percentage of elastic anisotropy,anisotropy in linear bulk modulus and directional dependence of elastic modulus,it is revealed that the anisotropy of TiFe_2 and Ti_4Fe_7(V) is ***,the density of states,charge density distribution and Mulliken population for TiFe_2 and Ti_4Fe_7(V) were calculated,suggesting there is a mixed bonding with metallic,covalent and ionic nature in TiFe_2 and Ti_4Fe_7(V) *** results also clarify that the reason for the improvement of plasticity with the addition of V in TiFe_2 is the weakened bonding of covalent feature between Ti and V atoms.

关键词： first-principles elastic properties alloying effect TiFe2 phase

New HB-weighted time delay estimation algorithm under impulsive noise environment

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Journal of Systems Engineering and Electronics 2008年第6期19卷 1102-1108页

作者： Sun Yongmei Qiu Tianshuang School of Electronic and Information Engineering Dalian Univ. of Technology Dalian 116024 P. R. China School of Electric and Information Engineering Dalian Jiaotong Univ. Dalian 116028 P. R. China

The traditional HB-weighted time-delay estimation （TDE） method degenerates under the impulsive noise environment. Two new time-delay estimation methods are proposed based on fractional lower order statistics （FLOS） according to the impulsive characteristics of fractional lower order α-stable noises. Theoretic analysis and computer simulations indicate that the proposed covariation based HB weighted （COV-HB） algorithm can suppress impulsive noises in one received signal for 1 ≤α≤ 2, whereas the other proposed fractional lower order eovariancebased HB weighted （FLOC-HB） algorithm has robust performance under arbitrary impulsive noise conditions for the whole range of 0 〈α≤ 2.

关键词： HB weighted time delay covariation fractional lower order covariance.

Time-delay Compensation Method for Networked Control System Based on Time-delay Prediction and Implicit PIGPC

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International Journal of Automation and computing 2015年第6期12卷 648-656页

作者： Zhong-Da Tian Xian-Wen Gao Bi-Lian Gong Tong Shi School of Information Science and Engineering Shenyang University of Technology School of Information Science and Engineering Northeastern University Department of Humanities Liaoning Forestry Vocation-Technical College

A network time-delay compensation method based on time-delay prediction and implicit proportional-integral-based generalized predictive controller(PIGPC) is proposed. The least squares support vector machine(LSSVM) is used to predict the current time-delay, the parameters of the least squares support vector machine are optimized by particle swarm optimization(PSO) algorithm,and the predicted time-delay is used instead of the actual time-delay as the parameters of the network time-delay compensation controller. In order to improve the compensation effect of implicit generalized predictive controller(GPC), this paper puts forward an implicit generalized predictive control algorithm with proportional-integral-based(PI) structure and designs the controller based on implicit PIGPC. Through the simulation results, the effectiveness of this design in the paper is verified.

关键词： Networked control system time-delay compensation p

A One-Dimensional Hybrid Simulation of DC/RF Combined Driven Capacitive Plasma

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Plasma Science and Technology 2012年第1期14卷 32-36页

作者： WANG Shuai XU Xiang WANG Younian Department of Physics College of SciencesNortheastern UniversityShenyang 110891China School of Physics and Optoelectronic Engineering Dalian University of TechnologyDalian 116024China

We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions （IEDs） and ion angle distributions （IADs） on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.

关键词： capacitively coupled plasmas DC/RF combined driven hybrid model IEDs IADs

Computer Model of Phase Transformation From Hot-Deformed Austenite in Niobium Microalloyed Steels

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Journal of Iron and Steel Research International 2007年第2期14卷 66-69页

作者： XU Yun-bo YU Yong-mei LIU Xiang-hua WANG Guo-dong State Key Lab of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

Based on thermodynamics and kinetics, a new mathematical model was developed to calculate the CCT diagrams and the transformation kinetics in low carbon niobium steels, in which the effect of deformation on the degree of supercooling was taken into account. The undercooling caused by deformation is the major reason for the increase of the starting transition temperature during continuous cooling. The critical cooling rate of bainite formation is within 2--5 ℃s for the studied niobium steels and deformation is suitable for the occurrence of pearlite. The ferrite volume fraction increases with the increase of the austenite boundary area, and decreases with the increase of the cooling rate. The calculated CCT diagrams and the volume fraction of each phase are in good agreement with the measurements.

关键词： low carbon niobium steel thermodynamics supercooling degree continuous cooling transformation computer model

Static Recrystallization and Precipitation Behavior of a Weathering Steel Microalloyed with Vanadium

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Journal of Materials Science & Technology 2013年第12期29卷 1197-1203页

作者： Hongyan Wu Linxiu Du Zhengrong Ai Xianghua Liu State Key Laboratory of Rolling and Automation Northeastern University

The static recrystallization （SRX） and precipitation behavior of a weathering steel microalloyed with vanadium were investigated through double-pass compression tests under controfled conditions using the MMS-300 thermal-mechanical simulator. The deformation temperatures ranged from 800 °C to 1000 °C, and the inter- pass time from 1 s to 500 s. The simulation results showed that SRX occurred after 5-10 s at the first compression deformation. The softening fraction of SRX was found to increase with increasing the deformation temperature and the pre-strain. However, the softening fraction scarcely changed during the process of strain-induced precipitation. In addition, the kinetics of SRX was described by the Avrami equation, and the Avrami exponent appeared to be closely associated with the deformation temperature. The microstructure evolution was investigated at the initiation and completion of recrystallization. The amount and distribution of the precipitates were analyzed. The relationship between the driving force of SRX and the pinning force of precipitation was discussed. Besides, the recrystallization inhibition was detected at the early stage of precipitation, and the pinning forces were found to be of a magnitude comparable to the driving force. Moreover, the pinning forces were found to increase with the degree of precipitation and reach a peak at the intermediate stage of precipitation, and finally reduce as the particles coarsened.

关键词： Vanadium-microalloyed weathering steel Static recrystallization Kinetics of SRX Microstructural evolution Precipitation

Tailoring electronic properties of two-dimensional antimonene with isoelectronic counterparts

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Chinese Physics B 2020年第3期29卷 41-49页

作者： Ye Zhang Huai-Hong Guo Bao-Juan Dong Zhen Zhu Teng Yang Ji-Zhang Wang Zhi-Dong Zhang College of Sciences Liaoning Shihua UniversityFushun 113001China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Materials Department University of CaliforniaSanta BarbaraCA 93106USA State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterparts SnTe and InI. We find that the band gap increases monotonically from Sb to SnTe to InI along with an increase in ionicity, independent of the structural phases. The band gaps of this material family cover the entire visible-light energy spectrum, ranging from 0.26 eV to 3.37 eV, rendering them promising candidates for optoelectronic applications. Meanwhile, band-edge positions of these materials are explored and all three types of band alignments can be achieved through properly combining antimonene with its isoelectronic counterparts to form heterostructures. The richness in electronic properties for this isoelectronic material family sheds light on possibilities to tailor the fundamental band gap of antimonene via lateral alloying or forming vertical heterostructures.

关键词： tailoring electronic properties two-dimensional antimonene isoelectronic counterparts

Influence of Hot Press Forming Techniques on Properties of Vehicle High Strength Steels

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Journal of Iron and Steel Research International 2011年第5期18卷 59-63页

作者： CHANG Ying MENG Zhao-huan YING Liang LI Xiao-dong MA Ning HU Ping School of Automotive Engineering State Key Laboratory of Structural Analysis for Industrial EquipmentDalian University of TechnologyDalian 116024LiaoningChina

Based on the combination of materials science and mechanical engineering,hot press forming process of the vehicle high strength steels was analyzed. The hot forming process included：heating alloys rapidly to austenite microstructures,stamping and cooling timely,maintaining pressure and quenching. The results showed that most of austenite microstructure was changed into uniform martensite by the hot press forming while the samples were heated at 900 ℃ and quenched. The optimal tensile strength and yield strength were up to 1530 MPa and 1000 MPa,respectively,and the shape deformation reached about 23%. And springback defect did not happen in the samples.

关键词： high strength steel lightweight hot forming martensite

Structural and electronic properties of transition-metal chalcogenides Mo5S4 nanowires

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Chinese Physics B 2019年第10期28卷 204-209页

作者： Ming-Shuai Qiu Huai-Hong Guo Ye Zhang Bao-Juan Dong Sajjad Ali Teng Yang College of Sciences Liaoning Shihua UniversityFushun 113001China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Transition-metal chalcogenide nanowires(TMCN) as a viable candidate for nanoscale applications have been attracting much attention for the last few decades. Starting from the rigid building block of M6 octahedra(M = transition metal),depending on the way of connection between M6 and decoration by chalcogenide atoms, multiple types of extended TMCN nanowires can be constructed based on some basic rules of backbone construction proposed here. Note that the well-known Chevrel-phase based M6X6 and M6X9(X = chalcogenide atom) nanowires, which are among our proposed structures, have been successfully synthesized by experiment and well studied. More interestingly, based on the construction principles, we predict three new structural phases(the cap, edge, and C&E phases) of Mo5S4, one of which(the edge phase) has been obtained by top-down electron beam lithography on two-dimensional MoS2, and the C&E phase is yet to be synthesized but appears more stable than the edge phase. The stability of the new phases of Mo5S4 is further substantiated by crystal orbital overlapping population(COOP), phonon dispersion relation, and thermodynamic calculation. The barrier of the structural transition between different phases of Mo5S4 shows that it is very likely to realize an conversion from the experimentally achieved structure to the most stable C&E phase. The calculated electronic structure shows an interesting band nesting between valence and conduction bands of the C&E Mo5S4 phase, suggesting that such a nanowire structure can be well suitable for optoelectronic sensor applications.

关键词： transition-metal chalcogenide nanowire