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J Llorca - One of the best experts on this subject based on the ideXlab platform.
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multiscale modelling of precipitation hardening in al cu alloys Dislocation Dynamics simulations and experimental validation
Acta Materialia, 2020Co-Authors: R Santosguemes, J Segurado, B Bellon, G Estebanmanzanares, Laurent Capolungo, J LlorcaAbstract:Abstract The mechanisms of Dislocation/precipitate interactions were analyzed in an Al–Cu alloy containing a homogeneous dispersion of θ′ precipitates by means of discrete Dislocation Dynamics simulations. The simulations were carried out within the framework of the discrete-continuous method and the precipitates were assumed to be impenetrable by Dislocations. The main parameters that determine the Dislocation/precipitate interactions (elastic mismatch, stress-free transformation strains, Dislocation mobility and cross-slip rate) were obtained from atomistic simulations, while the size, shape, spatial distribution and volume fraction of the precipitates were obtained from transmission electron microscopy. The predictions of the critical resolved shear stress (including the contribution of solid solution) were in agreement with the experimental results obtained by means of compression tests in micropillars of the Al–Cu alloy oriented for single slip. The simulations revealed that the most important contribution to the precipitation hardening of the alloy was provided by the stress-free transformation strains followed by the solution hardening and the Orowan mechanism due to the bow-out of the Dislocations around the precipitates.
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multiscale modelling of precipitation hardening in al cu alloys Dislocation Dynamics simulations and experimental validation
arXiv: Materials Science, 2020Co-Authors: R Santosguemes, J Segurado, B Bellon, G Estebanmanzanares, Laurent Capolungo, J LlorcaAbstract:The mechanisms of Dislocation/precipitate interactions were analyzed in an Al-Cu alloy containing a homogeneous dispersion of $\theta'$ precipitates by means of discrete Dislocation Dynamics simulations. The simulations were carried out within the framework of the discrete-continuous method and the precipitates were assumed to be impenetrable by Dislocations. The main parameters that determine the Dislocation/precipitate interactions (elastic mismatch, stress-free transformation strains, Dislocation mobility and cross-slip rate) were obtained from atomistic simulations, while the size, shape, spatial distribution and volume fraction of the precipitates were obtained from transmission electron microscopy. The predictions of the critical resolved shear stress (including the contribution of solid solution) were in agreement with the experimental results obtained by means of compression tests in micropillars of the Al-Cu alloy oriented for single slip. The simulations revealed that the most important contribution to the precipitation hardening of the alloy was provided by the stress-free transformation strains followed by the solution hardening and the Orowan mechanism due to the bow-out of the Dislocations around the precipitates.
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discrete Dislocation Dynamics simulations of Dislocation θ precipitate interaction in al cu alloys
Journal of The Mechanics and Physics of Solids, 2018Co-Authors: J Segurado, J Llorca, R Santosguemes, G Estebanmanzanares, Laurent Capolungo, Ioannis PapadimitriouAbstract:Abstract The mechanisms of Dislocation/precipitate interaction were studied by means of discrete Dislocation Dynamics within a multiscale approach. Simulations were carried out using the discrete continuous method in combination with a fast Fourier transform solver to compute the mechanical fields (Bertin et al., 2015). The original simulation strategy was modified to include straight Dislocation segments by means of the field Dislocation mechanics method and was applied to simulate the interaction of an edge Dislocation with a θ′ precipitate in an Al-Cu alloy. It was found that the elastic mismatch has a negligible influence on the Dislocation/precipitate interaction in the Al-Cu system. Moreover, the influence of the precipitate aspect ratio and orientation was reasonably well captured by the simple Orowan model in the absence of the stress-free transformation strain. Nevertheless, the introduction of the stress-free transformation strain led to dramatic changes in the Dislocation/precipitate interaction and in the critical resolved shear stress to overcome the precipitate, particularly in the case of precipitates with small aspect ratio. The new multiscale approach to study the Dislocation/precipitate interactions opens the possibility to obtain quantitative estimations of the strengthening provided by precipitates in metallic alloys taking into account the microstructural details.
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an analysis of the size effect on void growth in single crystals using discrete Dislocation Dynamics
Acta Materialia, 2009Co-Authors: J Segurado, J LlorcaAbstract:Abstract The effect of size on the mechanical behavior and the void growth rate in a voided single crystal was studied using two-dimensional discrete Dislocation Dynamics. The simulations were based on the methodology developed by Van der Giessen and Needleman [Van der Giessen E, Needleman A. Modell Simul Mater Sci Eng 1995;3:689], which was extended to non-convex domains through the use of finite elements with embedded discontinuities [Romero I, Segurado J, LLorca J. Modell Simul Mater Sci Eng 2008;16:035008]. Square crystals (in the range 0.5–2.5 μm) with an initial void volume fraction of 10% were deformed under plane strain conditions in uniaxial tension, uniaxial deformation and biaxial deformation. The results of the simulations show two size effects, one on the initial flow stress and strain-hardening rate of the voided crystal (“smaller is stronger”) and another on the void growth rate (“smaller is slower”). The magnitude of both size effects increased with triaxiality. The physical micromechanisms responsible for these size effects were elucidated from the simulation results.
Benoit Devincre - One of the best experts on this subject based on the ideXlab platform.
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modeling the creep properties of olivine by 2 5 dimensional Dislocation Dynamics simulations
Physical Review B, 2015Co-Authors: F Boioli, Benoit Devincre, Philippe Carrez, Patrick Cordier, Matthieu MarquilleAbstract:In this work we performed 2.5-dimensional (2.5D) Dislocation Dynamics simulations coupling climb with the glide Dislocation motion to model the creep behavior of olivine, one of the main component of the Earth's upper mantle. In particular, we present an application of this method to determine the creep strain rate in a material with high lattice resistance, such as olivine. We show that by including the climb mechanism we reach steady state creep conditions. Moreover, we find that a creep power law with a stress exponent close to 3 can be extracted from our simulations and we provide a model based on Orowan's law to predict the creep strain rates in the high temperature and low stress regime. The model presented is relevant to describe the plastic flow of olivine in the Earth's mantle deformation conditions and can be useful to derive the high temperature creep behavior of other materials.
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interaction of 1 0 0 Dislocation loops with Dislocations studied by Dislocation Dynamics in α iron
Journal of Nuclear Materials, 2015Co-Authors: X J Shi, Benoit Devincre, L. Dupuy, D Terentyev, L VincentAbstract:Abstract Interstitial Dislocation loops with Burgers vector of 〈1 0 0〉 type are formed in α-iron under neutron or heavy ion irradiation. As the density and size of these loops increase with radiation dose and temperature, these defects are thought to play a key role in hardening and subsequent embrittlement of iron-based steels. The aim of the present work is to study the pinning strength of the loops on mobile Dislocations. Prior to run massive Dislocation Dynamics (DD) simulations involving experimentally representative array of radiation defects and Dislocations, the DD code and its parameterization are validated by comparing the individual loop–Dislocation reactions with those obtained from direct atomistic Molecular Dynamics (MD) simulations. Several loop–Dislocation reaction mechanisms are successfully reproduced as well as the values of the unpinning stress to detach mobile Dislocations from the defects.
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modelling crystal plasticity by 3d Dislocation Dynamics and the finite element method the discrete continuous model revisited
Journal of The Mechanics and Physics of Solids, 2014Co-Authors: A Vattre, Benoit Devincre, Frederic Feyel, R Gatti, Sebastien Groh, O Jamond, A RoosAbstract:Abstract A unified model coupling 3D Dislocation Dynamics (DD) simulations with the finite element (FE) method is revisited. The so-called Discrete-Continuous Model (DCM) aims to predict plastic flow at the (sub-)micron length scale of materials with complex boundary conditions. The evolution of the Dislocation microstructure and the short-range Dislocation–Dislocation interactions are calculated with a DD code. The long-range mechanical fields due to the Dislocations are calculated by a FE code, taking into account the boundary conditions. The coupling procedure is based on eigenstrain theory, and the precise manner in which the plastic slip, i.e. the Dislocation glide as calculated by the DD code, is transferred to the integration points of the FE mesh is described in full detail. Several test cases are presented, and the DCM is applied to plastic flow in a single-crystal Nickel-based superalloy.
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Dislocation Dynamics based crystal plasticity law for the low and high temperature deformation regimes of bcc crystal
Acta Materialia, 2013Co-Authors: Ghiath Monnet, Ludovic Vincent, Benoit DevincreAbstract:Abstract Based on recent Dislocation Dynamics simulations investigations, a set of constitutive equations and model parameters for the description of plasticity of body-centered cubic materials is proposed. Assuming the flow stress to be controlled at low temperatures by the mobility of screw Dislocations and by forest interactions at high temperatures, this model allows for the prediction of the mechanical behavior in monotonic loading over a large range of temperatures and strain rates. The consideration of the difference in mobility between screw and non-screw Dislocations is found to affect strain hardening in a complex manner. The constitutive equations are implemented in a finite-element method to simulate tensile tests on iron single crystal at different temperatures. The use of finite transformation formalism enables the computation of crystal rotations which affect slip system activities. The calculated critical resolved shear stress and crystal rotations are in good agreement with existing experimental results.
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Dislocation Dynamics simulations of slip systems interactions and forest strengthening in ice single crystal
Philosophical Magazine, 2013Co-Authors: Benoit DevincreAbstract:The contribution of forest interactions to flow stress and strain hardening in ice single crystals is evaluated from Dislocation Dynamics simulations. The systematic mapping of Dislocation–Dislocation interactions and the calculation of the interaction strength between slip systems suggest an important contribution of collinear annihilation reactions. Comparison with experiment shows that the forest strengthening induced by a small density of collinear Dislocation segments in cross-slip planes may have been underestimated in current models for ice plasticity.
Peter Gumbsch - One of the best experts on this subject based on the ideXlab platform.
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comparison of mechanical behaviour of thin film simulated by discrete Dislocation Dynamics and continuum crystal plasticity
Computational Materials Science, 2009Co-Authors: Filip Siska, D Weygand, Peter Gumbsch, Samuel ForestAbstract:3D finite element simulations of 9-grain multicrystalline aggregates are performed within the framework of the classical continuum crystal plasticity and discrete Dislocation Dynamics. The results are processed in a statistical way by ensemble averaging. The comparison is made at three levels: macroscopic stress–strain curves, average stress values per grain, local values of stress and plastic strain. The comparison shows that some similarities are observed in the stress and strain distributions in both simulations approaches. But there are also large discrepancies caused by the discrete nature of plasticity in DDD. The DDD simulations provide higher stress levels in the aggregate due to the small number of Dislocation sources and to the stress field induced by individual Dislocations.
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three dimensional Dislocation Dynamics simulation of the influence of sample size on the stress strain behavior of fcc single crystalline pillars
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: D Weygand, Peter Gumbsch, M Poignant, O KraftAbstract:Abstract The size-dependent flow stress in uniformly loaded pillars has been modeled using a discrete Dislocation Dynamics tool. Starting from Frank-Read sources of given length and random orientation, the simulated flow stress at 0.15% plastic strain shows a clear size effect, similar to experimental findings for larger strains. The scattering of the simulated stress–strain curves decreases with increasing sample size, which reflects that plasticity of small scale samples is very sensitive to the underlying Dislocation microstructure.
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micro bending tests a comparison between three dimensional discrete Dislocation Dynamics simulations and experiments
Acta Materialia, 2008Co-Authors: J. Senger, Christian Motz, D Weygand, Peter GumbschAbstract:Abstract Discrete Dislocation Dynamics simulations in three dimensions are performed on micro-sized bending beams and the results are compared with experiments. A strong size dependence of the flow stress σ f (or bending moment) is found. The flow stress scales approximately inversely with the beam thickness t. The simulations show that the Dislocation structure exhibits pronounced pile-ups around the neutral plane of the beam. The back stress from these pile-ups on the Dislocation sources is analyzed by means of an analytical pile-up model. It is shown that the scaling behavior σ f ∝ t - 1 can be explained by a combination of pile-up and source size limitation. Subsequently, the applicability of strain gradient plasticity models on micro-bending is discussed.
J Segurado - One of the best experts on this subject based on the ideXlab platform.
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multiscale modelling of precipitation hardening in al cu alloys Dislocation Dynamics simulations and experimental validation
Acta Materialia, 2020Co-Authors: R Santosguemes, J Segurado, B Bellon, G Estebanmanzanares, Laurent Capolungo, J LlorcaAbstract:Abstract The mechanisms of Dislocation/precipitate interactions were analyzed in an Al–Cu alloy containing a homogeneous dispersion of θ′ precipitates by means of discrete Dislocation Dynamics simulations. The simulations were carried out within the framework of the discrete-continuous method and the precipitates were assumed to be impenetrable by Dislocations. The main parameters that determine the Dislocation/precipitate interactions (elastic mismatch, stress-free transformation strains, Dislocation mobility and cross-slip rate) were obtained from atomistic simulations, while the size, shape, spatial distribution and volume fraction of the precipitates were obtained from transmission electron microscopy. The predictions of the critical resolved shear stress (including the contribution of solid solution) were in agreement with the experimental results obtained by means of compression tests in micropillars of the Al–Cu alloy oriented for single slip. The simulations revealed that the most important contribution to the precipitation hardening of the alloy was provided by the stress-free transformation strains followed by the solution hardening and the Orowan mechanism due to the bow-out of the Dislocations around the precipitates.
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multiscale modelling of precipitation hardening in al cu alloys Dislocation Dynamics simulations and experimental validation
arXiv: Materials Science, 2020Co-Authors: R Santosguemes, J Segurado, B Bellon, G Estebanmanzanares, Laurent Capolungo, J LlorcaAbstract:The mechanisms of Dislocation/precipitate interactions were analyzed in an Al-Cu alloy containing a homogeneous dispersion of $\theta'$ precipitates by means of discrete Dislocation Dynamics simulations. The simulations were carried out within the framework of the discrete-continuous method and the precipitates were assumed to be impenetrable by Dislocations. The main parameters that determine the Dislocation/precipitate interactions (elastic mismatch, stress-free transformation strains, Dislocation mobility and cross-slip rate) were obtained from atomistic simulations, while the size, shape, spatial distribution and volume fraction of the precipitates were obtained from transmission electron microscopy. The predictions of the critical resolved shear stress (including the contribution of solid solution) were in agreement with the experimental results obtained by means of compression tests in micropillars of the Al-Cu alloy oriented for single slip. The simulations revealed that the most important contribution to the precipitation hardening of the alloy was provided by the stress-free transformation strains followed by the solution hardening and the Orowan mechanism due to the bow-out of the Dislocations around the precipitates.
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discrete Dislocation Dynamics simulations of Dislocation θ precipitate interaction in al cu alloys
Journal of The Mechanics and Physics of Solids, 2018Co-Authors: J Segurado, J Llorca, R Santosguemes, G Estebanmanzanares, Laurent Capolungo, Ioannis PapadimitriouAbstract:Abstract The mechanisms of Dislocation/precipitate interaction were studied by means of discrete Dislocation Dynamics within a multiscale approach. Simulations were carried out using the discrete continuous method in combination with a fast Fourier transform solver to compute the mechanical fields (Bertin et al., 2015). The original simulation strategy was modified to include straight Dislocation segments by means of the field Dislocation mechanics method and was applied to simulate the interaction of an edge Dislocation with a θ′ precipitate in an Al-Cu alloy. It was found that the elastic mismatch has a negligible influence on the Dislocation/precipitate interaction in the Al-Cu system. Moreover, the influence of the precipitate aspect ratio and orientation was reasonably well captured by the simple Orowan model in the absence of the stress-free transformation strain. Nevertheless, the introduction of the stress-free transformation strain led to dramatic changes in the Dislocation/precipitate interaction and in the critical resolved shear stress to overcome the precipitate, particularly in the case of precipitates with small aspect ratio. The new multiscale approach to study the Dislocation/precipitate interactions opens the possibility to obtain quantitative estimations of the strengthening provided by precipitates in metallic alloys taking into account the microstructural details.
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an analysis of the size effect on void growth in single crystals using discrete Dislocation Dynamics
Acta Materialia, 2009Co-Authors: J Segurado, J LlorcaAbstract:Abstract The effect of size on the mechanical behavior and the void growth rate in a voided single crystal was studied using two-dimensional discrete Dislocation Dynamics. The simulations were based on the methodology developed by Van der Giessen and Needleman [Van der Giessen E, Needleman A. Modell Simul Mater Sci Eng 1995;3:689], which was extended to non-convex domains through the use of finite elements with embedded discontinuities [Romero I, Segurado J, LLorca J. Modell Simul Mater Sci Eng 2008;16:035008]. Square crystals (in the range 0.5–2.5 μm) with an initial void volume fraction of 10% were deformed under plane strain conditions in uniaxial tension, uniaxial deformation and biaxial deformation. The results of the simulations show two size effects, one on the initial flow stress and strain-hardening rate of the voided crystal (“smaller is stronger”) and another on the void growth rate (“smaller is slower”). The magnitude of both size effects increased with triaxiality. The physical micromechanisms responsible for these size effects were elucidated from the simulation results.
R Santosguemes - One of the best experts on this subject based on the ideXlab platform.
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multiscale modelling of precipitation hardening in al cu alloys Dislocation Dynamics simulations and experimental validation
Acta Materialia, 2020Co-Authors: R Santosguemes, J Segurado, B Bellon, G Estebanmanzanares, Laurent Capolungo, J LlorcaAbstract:Abstract The mechanisms of Dislocation/precipitate interactions were analyzed in an Al–Cu alloy containing a homogeneous dispersion of θ′ precipitates by means of discrete Dislocation Dynamics simulations. The simulations were carried out within the framework of the discrete-continuous method and the precipitates were assumed to be impenetrable by Dislocations. The main parameters that determine the Dislocation/precipitate interactions (elastic mismatch, stress-free transformation strains, Dislocation mobility and cross-slip rate) were obtained from atomistic simulations, while the size, shape, spatial distribution and volume fraction of the precipitates were obtained from transmission electron microscopy. The predictions of the critical resolved shear stress (including the contribution of solid solution) were in agreement with the experimental results obtained by means of compression tests in micropillars of the Al–Cu alloy oriented for single slip. The simulations revealed that the most important contribution to the precipitation hardening of the alloy was provided by the stress-free transformation strains followed by the solution hardening and the Orowan mechanism due to the bow-out of the Dislocations around the precipitates.
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multiscale modelling of precipitation hardening in al cu alloys Dislocation Dynamics simulations and experimental validation
arXiv: Materials Science, 2020Co-Authors: R Santosguemes, J Segurado, B Bellon, G Estebanmanzanares, Laurent Capolungo, J LlorcaAbstract:The mechanisms of Dislocation/precipitate interactions were analyzed in an Al-Cu alloy containing a homogeneous dispersion of $\theta'$ precipitates by means of discrete Dislocation Dynamics simulations. The simulations were carried out within the framework of the discrete-continuous method and the precipitates were assumed to be impenetrable by Dislocations. The main parameters that determine the Dislocation/precipitate interactions (elastic mismatch, stress-free transformation strains, Dislocation mobility and cross-slip rate) were obtained from atomistic simulations, while the size, shape, spatial distribution and volume fraction of the precipitates were obtained from transmission electron microscopy. The predictions of the critical resolved shear stress (including the contribution of solid solution) were in agreement with the experimental results obtained by means of compression tests in micropillars of the Al-Cu alloy oriented for single slip. The simulations revealed that the most important contribution to the precipitation hardening of the alloy was provided by the stress-free transformation strains followed by the solution hardening and the Orowan mechanism due to the bow-out of the Dislocations around the precipitates.
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discrete Dislocation Dynamics simulations of Dislocation θ precipitate interaction in al cu alloys
Journal of The Mechanics and Physics of Solids, 2018Co-Authors: J Segurado, J Llorca, R Santosguemes, G Estebanmanzanares, Laurent Capolungo, Ioannis PapadimitriouAbstract:Abstract The mechanisms of Dislocation/precipitate interaction were studied by means of discrete Dislocation Dynamics within a multiscale approach. Simulations were carried out using the discrete continuous method in combination with a fast Fourier transform solver to compute the mechanical fields (Bertin et al., 2015). The original simulation strategy was modified to include straight Dislocation segments by means of the field Dislocation mechanics method and was applied to simulate the interaction of an edge Dislocation with a θ′ precipitate in an Al-Cu alloy. It was found that the elastic mismatch has a negligible influence on the Dislocation/precipitate interaction in the Al-Cu system. Moreover, the influence of the precipitate aspect ratio and orientation was reasonably well captured by the simple Orowan model in the absence of the stress-free transformation strain. Nevertheless, the introduction of the stress-free transformation strain led to dramatic changes in the Dislocation/precipitate interaction and in the critical resolved shear stress to overcome the precipitate, particularly in the case of precipitates with small aspect ratio. The new multiscale approach to study the Dislocation/precipitate interactions opens the possibility to obtain quantitative estimations of the strengthening provided by precipitates in metallic alloys taking into account the microstructural details.