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Structural, electronic, and optical properties of ZnO_(1-x)Se_x alloys using first-principles calculations

Chinese Physics B 2013年第8期22卷 581-588页

作者： Muhammad Rashid Fayyaz Hussain Muhammad Imran S A Ahmad N A Noor M U Sohaib S M Alay-e-Abbas Department of Physics Simulation Laboratory the Islamia University of Bahawalpur63100 Pakistan Department of Physics University of the Punjab Quaid-e-Azam Campus54590 Lahore Pakistan Lahore Development Authority 54590 Lahore Pakistan Department of Physics GC University FaisalabadAllama Iqbal Road Faisalabad 38000 Pakistan

The structural, electronic, and optical properties of binary ZnO, ZnSe compounds, and their ternary ZnOl_xSex alloys are computed using the accurate full potential linearized augmented plane wave plus local orbital （FP-LAPW ＋ lo） method in the rocksalt （B 1） and zincblende （B3） crystallographic phases. The electronic band structures, fundamental energy band gaps, and densities of states for ZnO1_xSex are evaluated in the range 0 〈 x 〈 1 using Wu-Cohen （WC） generalized gradient approximation （GGA） for the exchange-correlation potential. Our calculated results of lattice parameters and bulk modulus reveal a nonlinear variation for pseudo-binary and their ternary alloys in both phases and show a considerable deviation from Vegard＇s law. It is observed that the predicted lattice parameter and bulk modulus are in good agreement with the available experimental and theoretical data. We establish that the composition dependence of band gap is semi-metallic in B1 phase, while a direct band gap is observed in B3 phase. The calculated density of states is described by taking into account the contribution of Zn 3d, O 2p, and Se 4s, and the optical properties are studied in terms of dielectric functions, refractive index, reflectivity, and energy loss function for the B3 phase and are compared with the available experimental data.

关键词： density functional theory alloys structural electronic optical properties

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Magnesium and its alloys for better future——The 10th anniversary of journal of magnesium and alloys

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Journal of Magnesium and alloys 2023年第10期11卷 3395-3398页

作者： Fusheng Pan National Engineering Research Center for Magnesium alloys Chongqing UniversityChongqing 400044China National Key Laboratory of Advanced Casting TechnologiesChina

Fifteen years ago, when I first discussed the establishment of Journal of Magnesium and alloys (JMA) with Prof. Karl Ulrich Kainer from Germany, the establishment of JMA was just a dream. In a flash, fifteen years have passed, and it has been ten years since the establishment of the Magnesium Alloy Journal. The dream has not only become a reality, but the impact on the Mg academic research and industry has exceeded our imagination.

关键词： alloys magnesium journal

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Correlation between the Local Atomic Structure of Melts and Glass Forming Ability in Zr-Cu-Ni-Al alloys

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Chinese Physics Letters 2013年第10期30卷 128-131页

作者：吴臣黄永江沈军 School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001

The correlation between the atomic structure of melts and glass forming ability(GFA)in Zr_(53)Cu_(18.7)Ni_(12)Al_(16.3) and Zr_(50.7)Cu_(28)Ni_(9)Al_(12.3)(abbreviated as Zr53 and Zr507,respectively)alloys are studied by first principle simulations.The topological structure can be described by the Al-centered Kasper polyhedra and other distorted clusters with extrinsic disclinations.Due to the lower Al content in the Zr507 melts,its number of icosahedra is larger than that of the Zr53 melts.Also,the icosahedra in the Zr507 melts possess smaller distortion than those of the Zr_(53) melts,making the icosahedra more stable in the Zr507 melts.These two structural differences contribute to the slow dynamics and further enhance the GFA in the Zr507 alloy.

关键词： alloys structure distortion

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Material properties of friction stir spot welded joints of dissimilar aluminum alloys

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中国有色金属学会会刊：英文版 2012年第S3期22卷 605-613页

作者： Chi-Sung JEON Sung-Tae HONG Yong-Jai KWON Hoon-Hwe CHO Heung Nam HAN Technical Research Center Hyundai Steel Company School of Mechanical Engineering University of Ulsan Department of Materials Science and Engineering University of Ulsan Department of Materials Science and Engineering Seoul National University

Mechanical properties and material mixing patterns of friction stir spot welded (FSSW) joints of dissimilar aluminum alloys were investigated.Two aluminum alloys typically used in automotive applications,5052-H32 and 6061-T6,were selected.During the experiment,the process parameters including the z-axis force and torque histories were measured as a function of the tool displacement.The mechanical properties were investigated by microhardness measurements of the joint,and the material mixing in the stir zone was investigated by EPMA.The experimental results illustrate different process parameter histories,material mixing in the stir zone and material properties including microhardness distributions for FSSW joints of dissimilar aluminum alloys,likely due to different mechanical behaviors of the selected aluminum alloys in the FSSW process temperature range.

关键词： friction stir spot welding dissimilar aluminum alloys force histories torque histories microhardness

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Shock Compression of the New 47Zr45Ti5Al3V alloys up to 200GPa

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Chinese Physics Letters 2013年第6期30卷 165-168页

作者：张品亮龚自正姬广富王青松宋振飞曹燕王翔 Key Laboratory of Advanced Technologies of Materials of Ministry of Education School of Material Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031 National Key Laboratory of Science and Technology on Reliability and Environment Engineering Beijing Institute of Spacecraft Environment EngineeringBeijing 100094 Laboratory for Shock Wave&Detonation Physics Research Institute of Fluid PhysicsChina Academy of Engineering Physics(CAEP)Mianyang 621900

Shock compression experiments on a new kind of 47Zr45Ti5Al3V alloys at pressures between 28 and 200 GPa are performed using a two-stage light gas gun.The Hugoniot data are obtained by combining the impedance-match method and the electrical probe technique.The relationship between the shock wave velocity Us and particle velocity up can be described linearly by U_(s)=4.324(±0.035)+1.177(±0.012)up.No obvious evidence of phase transition is found in the shock compression pressure range.The calculated U_(s)-up relationship obtained from the additive principle is different from the experimental data,indicating that theα→βphase transition occurs below 28 GPa.The Grüneisen parameterγobtained from the experimental data can be expressed byγ=1.277(ρ0/ρ).The zero-pressure bulk modulus B0s=97.96 GPa and its pressure derivative B_(0s)=3.68.The P–V–T equation of state for 47Zr45Ti5Al3V is given using the Vinet equation of state to describe the cold curve and the Debye model for the thermal contributions.

关键词： technique. alloys transition

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Effect Mechanism of a Direct Current on the Solidification of Immiscible alloys

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Chinese Physics Letters 2012年第8期29卷 265-268页

作者：江鸿翔赵九洲 Institute of Metal Research Chinese Academy of SciencesShenyang 110016

Continuous solidification experiments are carried out with Al-Pb alloys under the effect of a direct current.The microstructure evolution in the samples is calculated.The numerical results obtained indicate that a direct current has great effects on the solidification of immiscible alloys.It mainly affects the microstructure evolution during a liquid-liquid decomposition by changing the spatial motions of the minority phase droplets and the temperature field in front of the solidification interface.A sample with either a well dispersed or a core/shell microstructure can be obtained by solidifying Al-Pb alloys under the effect of properly selected direct currents.

关键词： solidification microstructure alloys

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Raman Scattering Study of In_(x)Ga_(1-x)N alloys with Low Indium Compositions

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Chinese Physics Letters 2012年第2期29卷 211-213页

作者：滕龙张荣谢自力陶涛张曌李烨操刘斌陈鹏韩平郑有炓 Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials Department of Electronic Science and EngineeringNanjing UniversityNanjing 210093

In_(x)Ga_(1-x)N alloys with low indium composition x in the range 0.13 ≤ x ≤ 0.23 are systematically studied mainly based on a Raman scattering technique.Scanning electron microscopy and x-ray diffraction results show that our samples can be divided into two groups:pseudomorphic (0.13 ≤ x ≤ 0.16) and relaxed (0.18 ≤ x ≤ 0.23).The prominent enhancement of A1 longitudinal-optical (LO) mode is found with 325nm laser excitation.For pseudomorphic samples,the frequencies of A1 (LO) phonons agree well with the theoretical predictions,which verifies that the samples are fully strained.For relaxed In_(x)Ga_(1-x)N samples,a linear dependence of the A1 (LO) mode frequency is obtained:Ωo(x) =(740.8 ± 3.3) - (143.1 ± 16.0)x,which is the evidence of one-mode behavior in In_(x)Ga_(1-x)N ternary alloys.Residual strains in these partially relaxed samples are also evaluated.

关键词： technique relaxed alloys

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Be-composition effect on structure,electronic and optical properties of Be_xZn_(1-x)O alloys

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Chinese Physics B 2011年第3期20卷 328-335页

作者：吕兵周勋令狐荣锋王晓璐杨向东 Institute of Atomic and Molecular Physics Sichuan University School of Physics and Electronic Science Guizhou Normal University College of Science Guizhou UniversityInstitute of New Optoelectronic Materials and Technology Guizhou University

This paper carries out first principles calculation of the structure, electronic and optical properties of BexZn1-xO alloys based on the density-functional theory for the compositions x = 0.0, 0.25, 0.5, 0.75, 1.0. The lattice constants deviations of alloys obey Vegard＇s law well. The BexZn1-xO alloys have the direct band gap （Г-Г） character, and the bowing coefficients axe less than the available theoretical values. Moreover, it investigates in detail the optical properties （dielectric functions, absorption spectrum and refractive index） of these ternary mixed crystals. The obtained results agree well with the available theoretical and experimental values.

关键词： alloys optical properties generalized gradient approximation,BexZn1-xO

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Machine-learning-based intelligent framework for discovering refractory high-entropy alloys with improved high-temperature yield strength

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npj Computational Materials 2022年第1期8卷 2247-2257页

作者： Stephen A.Giles Debasis Sengupta Scott R.Broderick Krishna Rajan CFD Research Corporation 6820 Moquin Dr.NWHuntsvilleAL35806US Department of Material Design and Innovation University at Buffalo120 Bonner HallBuffaloNY14260USA

Refractory high-entropy alloys(RHEAs)show significant elevated-temperature yield strengths and have potential to use as high-performance materials in gas turbine engines.Exploring the vast RHEA compositional space experimentally is challenging,and a small fraction of this space has been explored to date.This work demonstrates the development of a state-of-the-art machine learning framework coupled with optimization methods to intelligently explore the vast compositional space and drive the search in a direction that improves high-temperature yield strengths.Our yield strength model is shown to have a significantly improved predictive accuracy relative to the state-of-the-art approach,and also provides inherent uncertainty quantification through the use of repeated k-fold cross-validation.Upon developing and validating a robust yield strength prediction model,the coupled framework is used to discover RHEAs with superior high temperature yield strength.We have shown that RHEA compositions can be customized to have maximum yield strength at a specific temperature.

关键词： strength alloys entropy

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Automation of diffusion database development in multicomponent alloys from large number of experimental composition profiles

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npj Computational Materials 2021年第1期7卷 320-332页

作者： Jing Zhong Li Chen Lijun Zhang State Key Laboratory of Powder Metallurgy Central South UniversityChangshaHunanChina Shenzhen Research Institute Central South UniversityShenzhenChina

Nowadays,the urgency for the high-quality interdiffusion coefficients and atomic mobilities with quantified uncertainties in multicomponent/multi-principal element alloys,which are indispensable for comprehensive understanding of the diffusioncontrolled processes during their preparation and service periods,is merging as a momentous trending in materials community.However,the traditional exploration approach for database development relies heavily on expertize and labor-intensive computation,and is thus intractable for complex systems.In this paper,we augmented the HitDIC(high-throughput determination of interdiffusion coefficients,https://***)software into a computation framework for automatic and efficient extraction of interdiffusion coefficients and development of atomic mobility database directly from large number of experimental composition profiles.Such an efficient framework proceeds in a workflow of automation concerning techniques of data-cleaning,feature engineering,regularization,uncertainty quantification and parallelism,for sake of agilely establishing high-quality kinetic database for target alloy.Demonstration of the developed infrastructures was finally conducted in fcc CoCrFeMnNi high-entropy alloys with a dataset of 170 diffusion couples and 34,000 composition points for verifying their reliability and efficiency.Thorough investigation over the obtained kinetic descriptions indicated that the sluggish diffusion is merely unilateral interpretation over specific composition and temperature ranges affiliated to limited dataset.It is inferred that data-mining over large number of experimental data with the combinatorial infrastructures are superior to reveal extremely complex composition-and temperature-dependent thermal–physical properties.

关键词： alloys diffusion database

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