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First-principles-based prediction of yield strength in the RhIrPdPtNiCu high-entropy alloy

npj Computational Materials 2019年第1期5卷 1017-1023页

作者： Binglun Yin william a.curtin Laboratory for Multiscale Mechanics Modeling(LAMMM)and National Centre for Computational Design and Discovery of Novel Materials(NCCR MARVEL) École Polytechnique Fédérale de Lausanne1015 LausanneSwitzerland

High-entropy alloys are random alloys with five or more components,often near equi-composition,that often exhibit excellent mechanical *** the design of new materials across the wide composition space requires an ability to compute necessary underlying material parameters via ab initio ***,density functional theory is used to compute the elemental misfit volumes,alloy lattice constant,elastic constants,and stable stacking fault energy in the fcc noble metal *** properties are then used in a recent theory for the temperature and strain-rate dependent yield *** parameter-free prediction of 583 MPa is in excellent agreement with the measured value of 527 *** quantitative connection between alloy composition and yield strength,without any experimental input,motivates this general density functional theory-based methodological path for exploring new potential high-strength high-entropy alloys,in this and other alloy classes,with the chemical accuracy of first-principles methods.

关键词： alloy strength properties.

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Screw dislocation structure and mobility in body centered cubic Fe predicted by a Gaussian Approximation Potential

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npj Computational Materials 2018年第1期4卷 90-96页

作者： Francesco Maresca Daniele Dragoni Gábor Csányi Nicola Marzari william a.curtin Laboratory for Multiscale Mechanics Modeling(LAMMM) Institute of Mechanical EngineeringÉcole Polytechnique Fédérale de LausanneLausanne CH-1015Switzerland Theory and Simulation of Materials(THEOS) and National Centre for Computational Design and Discovery of Novel Materials(NCCR MARVEL)École Polytechnique Fédérale de LausanneLausanne CH-1015Switzerland Dipartimento di Scienza dei Materiali Universitàdi Milano-BicoccaVia R.Cozzi 55Milan I-20125Italy Department of Engineering University of CambridgeTrumpington StreetCambridge CB21PZUK

The plastic flow behavior of bcc transition metals up to moderate temperatures is dominated by the thermally activated glide of screw dislocations,which in turn is determined by the atomic-scale screw dislocation core structure and the associated kink-pair nucleation mechanism for *** complex plasticity phenomena requires the simulation of many atoms and interacting dislocations and *** sizes are beyond the scope of first-principles methods and thus require empirical interatomic *** for the technological important case of bcc Fe,existing empirical interatomic potentials yield spurious ***,the structure and motion of the screw dislocations in Fe are studied using a new Gaussian Approximation Potential(GAP)for bcc Fe,which has been shown to reproduce the potential energy surface predicted by density-functional theory(DFT)and many associated *** Fe GAP predicts a compact,non-degenerate core structure,a single-hump Peierls potential,and glide on{110},consistent with DFT *** thermally activated motion at finite temperatures occurs by the expected kink-pair nucleation and propagation *** stress-dependent enthalpy barrier for screw motion,computed using the nudgedelastic-band method,follows closely a form predicted by standard theories with a zero-stress barrier of~1 eV,close to the experimental value of 0.84 eV,and a Peierls stress of~2 GPa consistent with DFT predictions of the Peierls potential.

关键词： structure dislocation cubic

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原子/离散位错耦合材料模拟方法及应用

原子/离散位错耦合材料模拟方法及应用

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中国力学学会学术大会'2009

作者：曲绍兴周昊飞 william a.curtin 浙江大学航空航天学院 Division of Engineering Brown University

发展了一种"有限温度下动态原子/离散位错耦合材料模拟方法",进行跨原子、细观和宏观尺度的含缺陷晶体材料力学性能研究。在原子区域,采用分子动力学方法并选择合适的温控方法;连续区域中离散位错模型与动态有限元相结合;通过原子/连续... 详细信息

发展了一种"有限温度下动态原子/离散位错耦合材料模拟方法",进行跨原子、细观和宏观尺度的含缺陷晶体材料力学性能研究。在原子区域,采用分子动力学方法并选择合适的温控方法;连续区域中离散位错模型与动态有限元相结合;通过原子/连续区域界面及交叠带原子的位移实现不同空间区域信息的传递。该方法具有(1)保

关键词：多尺度耦合离散位错孪晶塑性变形

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地球演化历史中氧逸度变化对壳幔循环启动、风化和超大陆循环的指示

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Science Bulletin 2024年第1期69卷 97-102页

作者：王瑞邬绍宸 Roberto F.Weinberg william J.Collins Peter A.Cawood State Key Laboratory of Geological Processes and Mineral Resources Institute of Earth SciencesChina University of GeosciencesBeijing 100083China Frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing 100083China School of Earth Atmosphere and EnvironmentMonash UniversityClayton VIC 3800Australia The Institute for Geoscience Research Curtin UniversityPerth WA 6102Australia

We apply a zircon redox index to a global compilation of detrital zircons to track the variation of oxidation state,expressed asΔFMQ,through Earth's *** from I-type rocks,which comprise mantle and crustal igneous protoliths,including tonalite–trondhjemite–granodiorites(TTGs),generally have a high oxidation state(ΔFMQ>0).In contrast,zircons from igneous rocks derived from supracrustal source rocks(S-type)are commonly reduced(ΔFMQ0 over the last 3 *** that the redox state of magmas is independent of crustal thickness and silica variation,and elevated values are likely more closely related to tectonic setting,we suggest that the consistent averageΔFMQ>0 from ca.3.5 Ga onwards relates to recycling of oceanic lithosphere back into the mantle in what eventually became established as subduction *** more reduced magmas associated with sedimentary sources,became established at 2.6 Ga,presumably in response to continental rocks rising above sealevel,and follow peaks of productivity associated with the supercontinent cycle.

关键词： Oxidation state Supercontinent Weathering Subduction Zircon Granite

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地球演化历史中氧逸度变化对壳幔循环启动、风化和超大陆循环的指示（英文）

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Science Bulletin 2024年第1期 97-102页

作者：王瑞邬绍宸 Roberto F.Weinberg william J.Collins Peter A.Cawood State Key Laboratory of Geological Processes and Mineral Resources Institute of Earth Sciences China University of Geosciences Frontiers Science Center for Deep-time Digital Earth China University of Geosciences (Beijing) School of Earth Atmosphere and Environment Monash University The Institute for Geoscience Research Curtin University

We apply a zircon redox index to a global compilation of detrital zircons to track the variation of oxidation state, expressed as ΔFMQ, through Earth’s history. Those from I-type rocks, which comprise mantle and crustal igneous protoliths, including tonalite–trondhjemite–granodiorites(TTGs), generally have a high oxidation state(ΔFMQ > 0). In contrast, zircons from igneous rocks derived from supracrustal source rocks(S-type) are commonly reduced(ΔFMQ 0 over the last 3 Ga. Given that the redox state of magmas is independent of crustal thickness and silica variation, and elevated values are likely more closely related to tectonic setting, we suggest that the consistent average ΔFMQ > 0 from ca.3.5 Ga onwards relates to recycling of oceanic lithosphere back into the mantle in what eventually became established as subduction zones. The more reduced magmas associated with sedimentary sources, became established at 2.6 Ga, presumably in response to continental rocks rising above sealevel, and follow peaks of productivity associated with the supercontinent cycle.

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Soil particle size range correction for improved calibration relationship between the laser-diffraction method and sieve-pipette method

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Pedosphere 2021年第1期31卷 134-144页

作者： Weiwen QIU Wei HU Denis curtin Lidia MOTOI New Zealand Institute for Plant&Food Research Limited Private Bag 4704Christchurch 8140New Zealand

Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size distribution, but the results usually differ from those obtained by the traditional sieve-pipette method(SPM). This difference can persist even when calibration is applied between the two methods. This partly relates to the different size ranges of particles measured by the two methods as a result of different operational principles, i.e., particle sedimentation according to Stokes’ Law vs. Mie theory for laser beam scattering. The objective of this study was to identify particle size ranges of LDM equivalent to those measured by SPM and evaluate whether new calibration models based on size range correction can be used to improve LDM-estimated particle size fractions, using 51 soil samples with various texture collected from five soil orders in New Zealand. Particle size distribution was determined using both LDM and SPM. Compared with SPM, original data from LDM underestimated the clay fraction(< 2 μm), overestimated the silt fraction(2–53 μm), but provided a good estimation of the sand fraction(53–2 000 μm).Results from three statistical indices, including Pearson’s correlation coefficient, slope, and Lin’s concordance correlation coefficient, showed that the size ranges of < 2 and 2–53 μm defined by SPM corresponded with the < 5 and 5–53 μm size ranges by LDM, respectively. Compared with the traditional calibration(based on the same particle size ranges), new calibration models(based on the corrected size ranges of these two methods) improved the estimation of clay and silt contents by LDM. Compared with soil-specific models(i.e., different models were developed for different soils), a universal model may be more parsimonious for estimating particle size fractions if the samples to be assessed represent multiple soil orders.

关键词： laser diffraction Lin’s concordance correlation coefficient particle size distribution Pearson’s correlation coefficient sedimentation method soil separate soil texture

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英汉医用对话第1册

英汉医用对话第1册

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1979年

作者： Charles J.Hirsch James a.curtin 林尚清颜文俊等译

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英汉医用对话第2册

英汉医用对话第2册

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1979年

作者： Charles J.Hirsch James a.curtin 林尚清颜文俊等译

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Does Particulate Organic Matter Fraction Meet the Criteria for a Model Soil Organic Matter Pool?

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Pedosphere 2019年第2期29卷 195-203页

作者： Denis curtin Michael H.BEARE Weiwen QIU Joanna SHARP New Zealand Institute for Plant & Food Research Limited

There is a well-recognized need for improved fractionation methods to partition soil organic matter into functional pools. Physical separation based on particle size is widely used, yielding particulate organic matter(POM, i.e., free or "uncomplexed" organic matter> 50 μm) as the most labile fraction. To evaluate whether POM meets criteria for an ideal model pool, we examined whether it is:1) unique, i.e., found only in the > 50 μm fraction and 2) homogeneous, rather than a composite of different subfractions. Following ultrasonic dispersion, sand(> 50 μm) along with coarse(20–50 μm) and fine(5–20 μm) silt fractions were isolated from a silt loam soil under long-term pasture at Lincoln, New Zealand. The sand and silt fractions contained 20% and 21% of total soil C, *** adopted a sequential density separation procedure using sodium polytungstate with density increasing step-wise from 1.7 to 2.4 g cm^(-3) to recover organic matter(light fractions) from the sand and silt fractions. Almost all(ca. 90%) the organic matter in the sand fraction and a large proportion(ca. 60%–70%) in the silt fractions was recovered by sequential density separation. The results suggested that POM is a composite of organo-mineral complexes with varying proportions of organic and mineral materials. Part of the organic matter associated with the silt fractions shared features in common with POM. In a laboratory bio-assay, biodegradability of POM varied depending on land use(pasture > arable cropping). We concluded that POM is neither homogeneous nor unique.

关键词： biodegradability density separation labile fraction land use particle size fractionation sand silt sodium polytungstate

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Information technology : the breaking wave

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1998年

作者： curtin Dennis P.

Includes index.

ISBN: (数字)0256218471

ISBN: (纸本)0256218471

Includes index.

关键词： Information technology.

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