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Articles 1 - 11 of 11
Full-Text Articles in Engineering
High-Throughput Design Of High-Performance Lightweight High-Entropy Alloys, Rui Feng, Chuan Zhang, Michael C. Gao, Zongrui Pei, Fan Zhang, Yan Chen, Dong Ma, Ke An, Jonathan D. Poplawsky, Lizhi Ouyang, Yang Ren, Jeffrey A. Hawk, Michael Widom, Peter K. Liaw
High-Throughput Design Of High-Performance Lightweight High-Entropy Alloys, Rui Feng, Chuan Zhang, Michael C. Gao, Zongrui Pei, Fan Zhang, Yan Chen, Dong Ma, Ke An, Jonathan D. Poplawsky, Lizhi Ouyang, Yang Ren, Jeffrey A. Hawk, Michael Widom, Peter K. Liaw
Mathematical Sciences Faculty Research
Developing affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, currently developed ferritic superalloys still exhibit low high-temperature strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method to design light, strong, and low-cost high-entropy alloys for elevated-temperature applications. Through the high-throughput screening, precipitation-strengthened lightweight high-entropy alloys are discovered from thousands of initial compositions, which exhibit enhanced strengths compared to other counterparts at room and elevated temperatures. The experimental and theoretical understanding of both successful and failed cases in their strengthening mechanisms and order-disorder transitions further …
Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li
Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li
Mathematical Sciences Faculty Research
© 2020 The Author(s) In this paper, we investigate a system of governing equations for modeling wave propagation in graphene. Compared to our previous work (Yang et al., 2020), here we re-investigate the governing equations by eliminating two auxiliary unknowns from the original model. A totally new stability for the model is established for the first time. Since the finite element scheme proposed in Yang et al. (2020) is only first order in time, here we propose two new schemes with second order convergence in time for the simplified modeling equations. Discrete stabilities inheriting exactly the same form as the …
A Simplified Crossing Fiber Model In Diffusion Weighted Imaging, Sheng Yang, Kaushik Ghosh, Ken Sakaie, Satya S. Sahoo, Sarah J. Ann Carr, Curtis Tatsuoka
A Simplified Crossing Fiber Model In Diffusion Weighted Imaging, Sheng Yang, Kaushik Ghosh, Ken Sakaie, Satya S. Sahoo, Sarah J. Ann Carr, Curtis Tatsuoka
Mathematical Sciences Faculty Research
Diffusion MRI (dMRI) is a vital source of imaging data for identifying anatomical connections in the living human brain that form the substrate for information transfer between brain regions. dMRI can thus play a central role toward our understanding of brain function. The quantitative modeling and analysis of dMRI data deduces the features of neural fibers at the voxel level, such as direction and density. The modeling methods that have been developed range from deterministic to probabilistic approaches. Currently, the Ball-and-Stick model serves as a widely implemented probabilistic approach in the tractography toolbox of the popular FSL software package and …
Myopic Versus Farsighted Behaviors In A Low-Carbon Supply Chain With Reference Emission Effects, Jun Wang, Xianxue Cheng, Xinyu Wang, Hongtao Yang, Shuhua Zhang
Myopic Versus Farsighted Behaviors In A Low-Carbon Supply Chain With Reference Emission Effects, Jun Wang, Xianxue Cheng, Xinyu Wang, Hongtao Yang, Shuhua Zhang
Mathematical Sciences Faculty Research
The increased carbon emissions cause relatively climate deterioration and attract more attention of governments, consumers, and enterprises to the low-carbon manufacturing. This paper considers a dynamic supply chain, which is composed of a manufacturer and a retailer, in the presence of the cap-and-trade regulation and the consumers’ reference emission effects. To investigate the manufacturer’s behavior choice and its impacts on the emission reduction and pricing strategies together with the profits of both the channel members, we develop a Stackelberg differential game model in which the manufacturer acts in both myopic and farsighted manners. By comparing the equilibrium strategies, it can …
Thermodynamics Of Concentrated Solid Solution Alloys, Michael C. Gao, Chuan Zhang, Pan Gao, Fan Zhang, Lizhi Ouyang, Michael Widom, Jeffrey A. Hawk
Thermodynamics Of Concentrated Solid Solution Alloys, Michael C. Gao, Chuan Zhang, Pan Gao, Fan Zhang, Lizhi Ouyang, Michael Widom, Jeffrey A. Hawk
Mathematical Sciences Faculty Research
This paper reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation driving …
Computational Modeling Of High-Entropy Alloys: Structures, Thermodynamics And Elasticity, Michael C. Gao, Pan Gao, Jeffrey A. Hawk, Lizhi Ouyang, David E. Alman, Mike Widom
Computational Modeling Of High-Entropy Alloys: Structures, Thermodynamics And Elasticity, Michael C. Gao, Pan Gao, Jeffrey A. Hawk, Lizhi Ouyang, David E. Alman, Mike Widom
Mathematical Sciences Faculty Research
This article provides a short review on computational modeling on the formation, thermodynamics, and elasticity of single-phase high-entropy alloys (HEAs). Hundreds of predicted single-phase HEAs were re-examined using various empirical thermo-physical parameters. Potential BCC HEAs (CrMoNbTaTiVW, CrMoNbReTaTiVW, and CrFeMoNbReRuTaVW) were suggested based on CALPHAD modeling. The calculated vibrational entropies of mixing are positive for FCC CoCrFeNi, negative for BCC MoNbTaW, and near-zero for HCP CoOsReRu. The total entropies of mixing were observed to trend in descending order: CoCrFeNi > CoOsReRu > MoNbTaW. Calculated lattice parameters agree extremely well with averaged values estimated from the rule of mixtures (ROM) if the same crystal …
Tailoring Magnetic Behavior Of Cofemnnix (X = Al, Cr, Ga, And Sn) High Entropy Alloys By Metal Doping, Tingting Zuo, Michael C. Gao, Lizhi Ouyang, Xiao Yang, Yongqiang Cheng, Rui Feng, Shuying Chen, Peter K. Liaw, Jeffrey A. Hawk, Yong Zhang
Tailoring Magnetic Behavior Of Cofemnnix (X = Al, Cr, Ga, And Sn) High Entropy Alloys By Metal Doping, Tingting Zuo, Michael C. Gao, Lizhi Ouyang, Xiao Yang, Yongqiang Cheng, Rui Feng, Shuying Chen, Peter K. Liaw, Jeffrey A. Hawk, Yong Zhang
Mathematical Sciences Faculty Research
Magnetic materials with excellent performances are desired for functional applications. Based on the high-entropy effect, a system of CoFeMnNiX (X = Al, Cr, Ga, and Sn) magnetic alloys are designed and investigated. The dramatic change in phase structures from face-centered-cubic (FCC) to ordered body-centered-cubic (BCC) phases, caused by adding Al, Ga, and Sn in CoFeMnNiX alloys, originates from the potent short-range chemical order in the liquid state predicted by ab initio molecular dynamics (AIMD) simulations. This phase transition leads to the significant enhancement of the saturation magnetization (Ms), e.g., the CoFeMnNiAl alloy has Ms of 147.86 Am2/kg. First-principles density functional …
Large Scale Screening Of Low Cost Ferritic Steel Designs For Advanced Ultra Supercritical Boiler Using First Principles Methods, Lizhi Ouyang
Mathematical Sciences Faculty Research
Advanced Ultra Supercritical Boiler (AUSC) requires materials that can operate in corrosive environment at temperature and pressure as high as 760°C (or 1400°F) and 5000psi, respectively, while at the same time maintain good ductility at low temperature. We develop automated simulation software tools to enable fast large scale screening studies of candidate designs. While direct evaluation of creep rupture strength and ductility are currently not feasible, properties such as energy, elastic constants, surface energy, interface energy, and stack fault energy can be used to assess their relative ductility and creeping strength. We implemented software to automate the complex calculations to …
Elastic And Electronic Properties Of Ti2al(Cxn1−X) Solid Solutions, Sitaram Aryal, Ridwan Sakidja, Lizhi Ouyang, Wai-Yim Ching
Elastic And Electronic Properties Of Ti2al(Cxn1−X) Solid Solutions, Sitaram Aryal, Ridwan Sakidja, Lizhi Ouyang, Wai-Yim Ching
Mathematical Sciences Faculty Research
The elastic coefficients and mechanical properties (bulk modulus, shear modulus, Young's modulus and Poisson's ratio) of Ti2Al(CxN1−x) continuous solid solutions for x from 0 to 1 are calculated using ab initio DFT methods on 4×4×1 supercell models. It is shown that the properties of these solid solutions do not vary linearly with x. Although the lattice constant c is almost constant for x≤0.5, a increases linearly. For x>0.5, c starts to increase with x while the rate of increase in a slows down. For x between 0.5 and 0.85, the elastic coefficients and the mechanical parameters show interesting dependence …
Understanding The Factors That Control Theformation And Morphology Of Zn5(Oh)8(No3)2⋅2h2othrough Hydrothermal Route, Xu Liu, Chunrui Wang, Xiaoyun Liu, Lizhi Ouyang, Ziyin You, Yeqing Lu, Xiaoshuang Chen
Understanding The Factors That Control Theformation And Morphology Of Zn5(Oh)8(No3)2⋅2h2othrough Hydrothermal Route, Xu Liu, Chunrui Wang, Xiaoyun Liu, Lizhi Ouyang, Ziyin You, Yeqing Lu, Xiaoshuang Chen
Mathematical Sciences Faculty Research
The influence of the choice of ethanol-water volume ratio, concentration of zinc salt, and ZnO buffer layer on the formation andmorphology of Zn5(OH)8(NO3)2⋅2H2O grown from the hydrothermal route was systematically discussed. Experimental resultssuggested that Zn5(OH)8(NO3)2⋅2H2O rectangle sheets and Zn5(OH)8(NO3)2⋅2H2O upright-standing plates were obtained bylimiting ethanol-water volume ratio. The concentration of zinc salt was crucial for getting phase-pure Zn5(OH)8(NO3)2⋅2H2O. Thepresence of ZnO buffer layer could lead to the that chemical composition of product grown on the substrate was totally differentfrom the product grown in the solution. Possible formation mechanism of Zn5(OH)8(NO3)2⋅2H2O was also studied. Ramanspectrum of Zn5(OH)8(NO3)2⋅2H2O displays a complex behavior …
Structure And Properties Of The Low-Density Phase Ι-Al2o3 From First Principles, Sitaram Aryal, Paul Rulis, Lizhi Ouyang, Wai-Yim Ching
Structure And Properties Of The Low-Density Phase Ι-Al2o3 From First Principles, Sitaram Aryal, Paul Rulis, Lizhi Ouyang, Wai-Yim Ching
Mathematical Sciences Faculty Research
Of the various phases of transition alumina, iota-alumina (ι-Al2O3) is the least well known. It is considered to be the end member of the mullite series in the limit of zero Si content. The structural details of ι-Al2O3 are not available and its physical properties are totally unknown. Based on an appropriately modified structure of a high alumina content mullite phase close to the 9-1 mullite, we have successfully constructed a structural model for ι-Al2O3. The simulated x-ray diffraction (XRD) pattern of this model agrees well with a measured XRD pattern obtained from samples that claim to belong to ι-Al2O3. …