The Experts below are selected from a list of 45834 Experts worldwide ranked by ideXlab platform
William A. Curtin - One of the best experts on this subject based on the ideXlab platform.
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Quantum-to-continuum prediction of ductility loss in aluminium–magnesium Alloys due to dynamic strain aging
Nature Communications, 2014Co-Authors: S. M. Keralavarma, Allan F. Bower, William A. CurtinAbstract:Aluminum-Magnesium Alloys exhibit negative strain-rate sensitivity due to dynamic strain aging, causing reduced ductility at room temperature. Here, the authors develop an atomistically informed multiscale model that can predict the rate sensitivity and ductility as a function of the alloy chemistry. Negative strain-rate sensitivity due to dynamic strain aging in Aluminium–5XXX Alloys leads to reduced ductility and plastic instabilities at room temperature, inhibiting application of these Alloys in many forming processes. Here a hierarchical multiscale model is presented that uses (i) quantum and atomic information on solute energies and motion around a dislocation core, (ii) dislocation models to predict the effects of solutes on dislocation motion through a dislocation forest, (iii) a thermo-kinetic constitutive model that faithfully includes the atomistic and dislocation scale mechanisms and (iv) a finite-element implementation, to predict the ductility as a function of temperature and strain rate in AA5182. The model, which contains no significant adjustable parameters, predicts the observed steep drop in ductility at room temperature, which can be directly attributed to the atomistic aging mechanism. On the basis of quantum inputs, this multiscale theory can be used in the future to design new Alloys with higher ductility.
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Finite element implementation of a kinetic model of dynamic strain aging in aluminum–magnesium Alloys
International Journal for Numerical Methods in Engineering, 2010Co-Authors: Fan Zhang, Allan F. Bower, William A. CurtinAbstract:Soare and Curtin (Acta Mater. 2008; 56:4091-4101, 4046-4061) have recently developed a model of dynamic strain aging in solute-strengthened Alloys. Their constitutive law describes time-dependent solute strengthening using rate equations that can be calibrated using atomistic simulations. In this paper, their material model is incorporated into a continuum finite element simulation, with a view to completing a multi-scale method for predicting the formability of solute-strengthened Alloys. The Soare-Curtin model is first re-formulated as a state-variable constitutive law, which is suitable for finite element computations. An efficient numerical procedure is then developed to track the strength distribution of aging mobile and forest dislocations in the solid during deformation. The method is tested by simulating the behavior of a 3D Aluminum-Magnesium alloy tensile specimen subjected to uniaxial loading at constant nominal strain rate. The model predicts the influence of strain rate on the steady-state flow stress of Al-Mg Alloys, but no Portevin-Le Chatelier bands or serrated flow were observed in any of our simulations, and the influence of strain rate on tensile ductility is not predicted correctly. The reasons for this behavior and possible resolutions are discussed. Copyright (C) 2010 John Wiley & Sons, Ltd.
Allan F. Bower - One of the best experts on this subject based on the ideXlab platform.
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Quantum-to-continuum prediction of ductility loss in aluminium–magnesium Alloys due to dynamic strain aging
Nature Communications, 2014Co-Authors: S. M. Keralavarma, Allan F. Bower, William A. CurtinAbstract:Aluminum-Magnesium Alloys exhibit negative strain-rate sensitivity due to dynamic strain aging, causing reduced ductility at room temperature. Here, the authors develop an atomistically informed multiscale model that can predict the rate sensitivity and ductility as a function of the alloy chemistry. Negative strain-rate sensitivity due to dynamic strain aging in Aluminium–5XXX Alloys leads to reduced ductility and plastic instabilities at room temperature, inhibiting application of these Alloys in many forming processes. Here a hierarchical multiscale model is presented that uses (i) quantum and atomic information on solute energies and motion around a dislocation core, (ii) dislocation models to predict the effects of solutes on dislocation motion through a dislocation forest, (iii) a thermo-kinetic constitutive model that faithfully includes the atomistic and dislocation scale mechanisms and (iv) a finite-element implementation, to predict the ductility as a function of temperature and strain rate in AA5182. The model, which contains no significant adjustable parameters, predicts the observed steep drop in ductility at room temperature, which can be directly attributed to the atomistic aging mechanism. On the basis of quantum inputs, this multiscale theory can be used in the future to design new Alloys with higher ductility.
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Finite element implementation of a kinetic model of dynamic strain aging in aluminum–magnesium Alloys
International Journal for Numerical Methods in Engineering, 2010Co-Authors: Fan Zhang, Allan F. Bower, William A. CurtinAbstract:Soare and Curtin (Acta Mater. 2008; 56:4091-4101, 4046-4061) have recently developed a model of dynamic strain aging in solute-strengthened Alloys. Their constitutive law describes time-dependent solute strengthening using rate equations that can be calibrated using atomistic simulations. In this paper, their material model is incorporated into a continuum finite element simulation, with a view to completing a multi-scale method for predicting the formability of solute-strengthened Alloys. The Soare-Curtin model is first re-formulated as a state-variable constitutive law, which is suitable for finite element computations. An efficient numerical procedure is then developed to track the strength distribution of aging mobile and forest dislocations in the solid during deformation. The method is tested by simulating the behavior of a 3D Aluminum-Magnesium alloy tensile specimen subjected to uniaxial loading at constant nominal strain rate. The model predicts the influence of strain rate on the steady-state flow stress of Al-Mg Alloys, but no Portevin-Le Chatelier bands or serrated flow were observed in any of our simulations, and the influence of strain rate on tensile ductility is not predicted correctly. The reasons for this behavior and possible resolutions are discussed. Copyright (C) 2010 John Wiley & Sons, Ltd.
T Tanski - One of the best experts on this subject based on the ideXlab platform.
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study of selected properties of magnesium alloy az91 after heat treatment and forming
Journal of Materials Processing Technology, 2004Co-Authors: L Cižek, Miroslav Greger, Libor Pawlica, L A Dobrzanski, T TanskiAbstract:Abstract Magnesium and magnesium Alloys are primarily used in aeronautical and automobile industry in large variety of structural characteristics because of their favorable combination of tensile strength (160–365 MPa), elastic modulus (45 GPa), and low density (1740 kg/m3), which is two-thirds that of aluminum. Magnesium Alloys have high strength-to-weight ratio (tensile strength/density), comparable to those of other structural metals. Application, structure and mechanical properties of selected magnesium Alloys were investigated.
Isolda Costa - One of the best experts on this subject based on the ideXlab platform.
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corrosion resistance and microstructure characterization of rare earth transition metal aluminum magnesium Alloys
Journal of Alloys and Compounds, 2009Co-Authors: Everson Do Prado Banczek, L M C Zarpelon, R N Faria, Isolda CostaAbstract:Abstract This paper reports the results of investigation carried out to evaluate the corrosion resistance and microstructure of some cast Alloys represented by the general formula: La 0.7− x Pr x Mg 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 ( x = 0, 0.1, 0.3, 0.5, and 0.7). Scanning electron microscopy (SEM) and electrochemical methods, specifically, polarization curves and electrochemical impedance spectroscopy (EIS), have been employed in this study. The effects of Pr substitution on the composition of the various phases in the Alloys and their corrosion resistance have been studied. The electrochemical results showed that the alloy without Pr and the one with total La substitution showed the highest corrosion resistance among the studied Alloys. The corrosion resistance of the Alloys decreased when Pr was present in the lowest concentrations (0.1 and 0.3), but for higher Pr concentrations (0.5 and 0.7), the corrosion resistance increased. Corrosion occurred preferentially in a Mg-rich phase.
Fan Zhang - One of the best experts on this subject based on the ideXlab platform.
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Finite element implementation of a kinetic model of dynamic strain aging in aluminum–magnesium Alloys
International Journal for Numerical Methods in Engineering, 2010Co-Authors: Fan Zhang, Allan F. Bower, William A. CurtinAbstract:Soare and Curtin (Acta Mater. 2008; 56:4091-4101, 4046-4061) have recently developed a model of dynamic strain aging in solute-strengthened Alloys. Their constitutive law describes time-dependent solute strengthening using rate equations that can be calibrated using atomistic simulations. In this paper, their material model is incorporated into a continuum finite element simulation, with a view to completing a multi-scale method for predicting the formability of solute-strengthened Alloys. The Soare-Curtin model is first re-formulated as a state-variable constitutive law, which is suitable for finite element computations. An efficient numerical procedure is then developed to track the strength distribution of aging mobile and forest dislocations in the solid during deformation. The method is tested by simulating the behavior of a 3D Aluminum-Magnesium alloy tensile specimen subjected to uniaxial loading at constant nominal strain rate. The model predicts the influence of strain rate on the steady-state flow stress of Al-Mg Alloys, but no Portevin-Le Chatelier bands or serrated flow were observed in any of our simulations, and the influence of strain rate on tensile ductility is not predicted correctly. The reasons for this behavior and possible resolutions are discussed. Copyright (C) 2010 John Wiley & Sons, Ltd.
