Charles-Andre Gandin - Profile on Academia.edu (original) (raw)

Papers by Charles-Andre Gandin

Développement du réacteur Jules Horowitz – Étude métallurgique des défauts en soudage par faisceau d’électrons des alliages 6061

HAL (Le Centre pour la Communication Scientifique Directe), Sep 21, 2012

International audienc

Simulation of dendritic grain structures with Cellular Automaton–Parabolic Thick Needle model

Computational Materials Science, Oct 1, 2023

Modelling of grain structure and segregation in casting

HAL (Le Centre pour la Communication Scientifique Directe), Sep 28, 2005

International audienc

Cellular Automaton - Finite Element Modeling of Solidification Grain Structures - Extensions for Welding Processes

HAL (Le Centre pour la Communication Scientifique Directe), May 20, 2013

Cellular Automaton (CA) - Finite Element (FE) modeling is an efficient way to simulate the nuclea... more Cellular Automaton (CA) - Finite Element (FE) modeling is an efficient way to simulate the nucleation and growth of solidification grain structures in the context of casting processes. The methodology is reported to reach predictions for competition between columnar and equiaxed grain structures [1], coupling with microsegregation due to diffusion of species [2], macrosegregation due to fluid flow [3] and solid transport [4]. Recent comparisons with in-situ and real time x-ray radiography observations of solidifying alloys have also reported the current limits of the model and the need for more systematic characterizations of benchmark experiments [5]. One of the limits currently faced is the possibility to predict grain structures for large cast parts. While CAFE simulations can deal with volume sizes that are typical of the investment casting process [6], it requires extensions for other processes. The present keynote will list the efforts recently made to overpass this difficulty. They are based on parallel computations and dynamic allocation strategies in order to focus the computation resources in the region of the mushy zone. While the above progresses were necessary, they did not permit to handle simulation of the grain structure during welding processes. This is due to the fact that the coupon contains an initial grain structure that must be known at all locations and at any time in order to compute its local melting and the epitaxial growth from partially melted grains, typical of the solidification of the weld pool. A solution is presented in the present paper that permits simulation of multiple passes in welding processes for large computational domains. This achievement allows for grain structure manufacturing in welding processes and remelting surface treatments, as show in the figure below.

Modeling of Microstructural Evolution during Friction Stir Welding Applied to AA2024 Aluminum Alloys to Predict the Weld Mechanical Properties

HAL (Le Centre pour la Communication Scientifique Directe), Mar 15, 2015

International audienceFriction stir welding on aluminum alloy is seen as an alternative solution ... more International audienceFriction stir welding on aluminum alloy is seen as an alternative solution to riveting 2024 and 7075 aluminum alloys pieces in order to lighten aircraft structure. On these alloys, mechanical properties are linked to structural hardening due to solid state precipitation. A coupling approach is proposed in order to manage the precipitates distribution evolution taking place during the process and predict final properties. At macro-scale, a model is used to get the thermal evolution in the different parts of the welded zone. At micro-scale, a time-efficient precipitation simulation is developed based on a reliable thermodynamic description. A particle size distribution approach (PSD) is proposed to predict the nucleation, growth, dissolution and coarsening of stable and metastable phases. An accurate yield strength model is applied on the final distribution. Calibration is performed on differential scanning calorimetry studies (DSC), hardening test and tensile tests for both isothermal, non-isothermal and weld samples

Microstructure Modeling

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Sep 23, 2016

Analytical multicomponent microsegregation model for equiaxed globular growth with diffusion interaction between species

HAL (Le Centre pour la Communication Scientifique Directe), Jul 8, 2014

In casting processes, the development of one solid phase from the liquid gives rise to microsegre... more In casting processes, the development of one solid phase from the liquid gives rise to microsegregation. The liquid is enriched in solute species that diffuse to/from the solid/liquid interface. In multicomponent alloys, this enrichment mainly controls the solidification path and plays a major role for the estimation of the nature and amount of secondary phases. While numerical models usually rely on few approximations [1], analytical models also remain of interest for coupling with large scale simulations of casting processes [2]. Several models have been proposed to predict microsegregation [3]. However, very few models have been applied to multicomponent alloys and coupled with thermodynamic equilibrium calculations [4]. Moreover, interaction between species (or cross diffusion phenomena) is always neglected. We propose an analytical solution for a multicomponent microsegregation model with interaction between species. This paper relies on the approximation developed by Martorano et al. [3] initially proposed for binary alloys. The model is coupled with an energy balance and applied to simulate globulitic grain solidification in a ternary alloy during a cooling process. The influence of the cross-diffusion terms in the liquid diffusion matrix is demonstrated. A comparison is also provided with an exact solution using a front tracking method. References [1]Q. Chen, B. Sundman, Materials Transactions 43 (2002) 551-559 [2]H. Combeau, M. Zaloznik, S. Hans, P.-E. Richy, Metall. Mater. Trans. B 40 (2009) 289-304 [3]M.A. Martorano, C. Beckermann, Ch.-A. Gandin, Metall. and Mater. Trans. A 34 (2003), 1657-1673, 35A (2004) 1915 [4]H. Zhang, Ch. A. Gandin, H. Ben Hamouda, D. Tourret, K. Nakajima, J. He, ISIJ International 50 (2010) 1859-1866

Materials & Design, Dec 1, 2016

The GP(I) zone formation during quench is simulated in an industrial Aluminum alloy AA7449 75 mm ... more The GP(I) zone formation during quench is simulated in an industrial Aluminum alloy AA7449 75 mm thick plate by using a multi-class precipitation model. For this purpose, results of in situ SAXS experiments are reported. A methodology is presented that takes advantage of the collected data to derive i -a thermodynamic description for GP(I) zones from reversion heat treatments by using a solubility product and ii -the influence of excess vacancies on diffusion coefficients. This approach allows reproducing reasonably well the GP(I) zone formation measured during rapid cooling. Further, the simulated as-quenched surface yield strength compares well with experimental results reported in the literature.

Computation of Phase Transformation during Welding Processes

HAL (Le Centre pour la Communication Scientifique Directe), May 15, 2012

International audienc

Microstructural evolution during friction stir welding on AA2024 aluminium alloys - Application to the prediction of the mechanical properties

HAL (Le Centre pour la Communication Scientifique Directe), Sep 27, 2015

International audienceFriction stir welding on aluminium alloys is seen as an interesting option ... more International audienceFriction stir welding on aluminium alloys is seen as an interesting option to lighten aircraft structure. In particular, this process is considered as an alternative to the standard riveting process used for joining stiffeners to panels. However in aluminium alloys, mechanical properties are linked to structural hardening due to solid state precipitation. This phenomenon is known to affect the final properties of the welds after FSW. Thus the estimation of precipitate evolutions is of prime importance in order to deliver reliable welds to the aircraft industry. A time-efficient solid-state precipitation modelling for aluminium alloys based on a reliable thermodynamic description has been developed. A particle size distribution approach (PSD) is proposed for multi-components alloys to predict the nucleation, growth, dissolution and coarsening of both stable and metastable phases. At a larger scale, a macro-structural model is used to define precisely the thermo-mechanical evolutions of the metal parts. It allows to know the thermal evolution during the whole FSW process. Then, it is possible to couple the models in order to define precisely the precipitate evolutions in HAZ, TMAZ and nuggets domains leading to heterogeneous mechanical properties. Thereafter an accurate yield strength model is developed knowing the final precipitate radius distribution and precipitates properties. The calibration of this model is performed on differential scanning calorimetry studies (DSC), hardening test and tensile tests for both isothermal / non-isothermal treatments. This microstructural model is applied on a 2024-T3 aluminium alloy. The final mechanical properties are presented and discussed

IOP conference series, May 29, 2019

Modeling and experimental characterization of the microstructure and grains structure of Al-7wt%Si directionally solidified

HAL (Le Centre pour la Communication Scientifique Directe), Sep 27, 2010

Elsevier eBooks, 2022

1. Introduction 2) Directional solidification and related defects 2.1) Generalities on the castin... more 1) Introduction 2) Directional solidification and related defects 2.1) Generalities on the casting processes 2.1.1) The Bridgman-Stockbarger casting process 2.1.2) Alternate casting processes 2.2) Casting defects 2.2.1) Crystal structure 2.2.2) Microstructure and microsegregation 2.2.3) Freckles 2.2.4) Deformation related defects 3) Heat treatments and microstructure optimizations 3.1) Generalities on heat treatments 3.1.1) Solution heat treatment 3.1.2) Aging heat treatments 3.2) Defects and optimizations 3.2.1) Incipient melting 3.2.2) Optimizations 4) Mechanical properties sensitivity to the processing parameters 4.1) Creep and tensile properties 4.2) Fatigue properties 5) Conclusions References

npj Microgravity

Space levitation processing allows researchers to conduct benchmark tests in an effort to underst... more Space levitation processing allows researchers to conduct benchmark tests in an effort to understand the physical phenomena involved in rapid solidification processing, including alloy thermodynamics, nucleation and growth, heat and mass transfer, solid/liquid interface dynamics, macro- and microstructural evolution, and defect formation. Supported by ground-based investigations, a major thrust is to develop and refine robust computational tools based on theoretical and applied approaches. This work is accomplished in conjunction with experiments designed for precise model validation with application to a broad range of industrial processes.

Thermomechanical analysis of the solidification of fused cast alumina-zirconia-silica refractory blocks

IOP Conference Series: Materials Science and Engineering

Cooling history of fused cast Alumina-Zirconia-Silica (AZS) refractory blocks is recorded with th... more Cooling history of fused cast Alumina-Zirconia-Silica (AZS) refractory blocks is recorded with thermocouples. Postmortem investigations are performed including hot tears. Discussion about solidification path is done with the purpose to better understand phenomena occurring during casting. Heat transfer simulations are compared with recorded temperature histories. Mechanical outputs from THERCAST® are analyzed, revealing the possibility to calibrate the risk of hot tears formation by considering a cumulated strain based criterion.

International Journal of Thermal Sciences, 2021

Thermal contact resistance between two adjacent materials is one of the major concerns in a large... more Thermal contact resistance between two adjacent materials is one of the major concerns in a large variety of practical situations in heat transfer. The presence of this resistance yields a temperature jump across the interface. Due to this discontinuity, numerical modelling of thermal contact resistance runs into difficulties. In this work, we propose a simple and efficient numerical model to account for thermal contact resistance at immersed interfaces in multi-material heat transfer. The present model is based on the diffuse interface method. The effect of contact resistance between two adjacent materials is accounted for in the mixing laws of the thermal conductivity and the heat capacity. The model is validated through different test cases, including both steady and unsteady conduction, and applied to simulation of chill cooling and solidification of a steel sample on board the International Space Station.

Computers & Fluids, 2019

The oscillation of a levitated drop is a widely used technique for the measurement of the surface... more The oscillation of a levitated drop is a widely used technique for the measurement of the surface tension and viscosity of liquids. Analyses are mainly based on theories developed in the nineteenth century for surface tension driven oscillations of a spherical, force-free, liquid drop. However, a complete analysis with both analytical and numerical approaches to study the damped oscillations of a viscous liquid drop remains challenging. We first propose in this work an extension of the theory that includes the coupled effects of surface tension and viscosity. The analytical solution permits derivation of both properties simultaneously, which is of interest for fluid with unknown viscosity. Then, the robustness of an Eulerian framework to simulate the fluid flow is discussed. Simulations of different oscillations modes for a liquid iron droplet immersed in a low density gas and comparisons with the derived theory are detailed and presented.

Materialia, 2018

Competitive grain growth during the directional solidification of a polycrystalline binary alloy ... more Competitive grain growth during the directional solidification of a polycrystalline binary alloy is investigated by performing systematic three-dimensional large-scale phase-field simulations with the GPU supercomputer TSUBAME2.5 at the Tokyo Institute of Technology. Contrary to two-dimensional investigations, in which an unusual growth of unfavorably oriented (UO) grains has been observed frequently in preference to favorably oriented (FO) ones, the grain selection in the present three-dimensional simulations follows essentially the Walton and Chalmers model, in which FO grains are predominant. The UO dendritic grains persist for longer times than the UO cellular grains, and the FO dendritic grains remain smaller than the FO cellular ones. The change in the number of grains follows a power law, with an exponent that is much lower than that of the Kolmogorov's model describing a purely geometrical growth selection.

IOP Conference Series: Materials Science and Engineering, 2016

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Numerical Simulation of Solidification, Homogenization, and Precipitation in an Industrial Ni-Based Superalloy

Metallurgical and Materials Transactions A, 2016

AbstractA comprehensive simulation approach integrating solidification, homogenization, and preci... more AbstractA comprehensive simulation approach integrating solidification, homogenization, and precipitation during aging has been used to predict the formation of γ/γ′ microstructures in the AM1 nickel-based superalloy. The particle size distribution of intradendritic γ′ precipitates after aging was calculated with a multicomponent diffusion model coupled with CALPHAD thermodynamics for the equilibrium at the interface. The influence of residual microsegregation after homogenization and quenching was analyzed through different initial conditions obtained from calculations of the concentration profiles in the primary γ dendritic microstructure during solidification and the homogenization heat treatment. While the global sequence of precipitation remains qualitatively the same, substantial differences in the final volume fraction of γ′ precipitates were predicted between the core and the periphery of a former dendrite arm, for typical homogenization and aging conditions. To demonstrate the relevance of the developed simulation approach, the model was also used to investigate modified precipitation heat treatments. The simulations showed that relatively short heat treatments based on slow continuous cooling could potentially replace the extended isothermal heat treatments which are commonly used. Slow continuous cooling conditions can lead to similar γ′ precipitates radii and volume fractions, the main differences with isothermal heat treatments lying in a narrower particle size distribution.

Développement du réacteur Jules Horowitz – Étude métallurgique des défauts en soudage par faisceau d’électrons des alliages 6061

HAL (Le Centre pour la Communication Scientifique Directe), Sep 21, 2012

International audienc

Simulation of dendritic grain structures with Cellular Automaton–Parabolic Thick Needle model

Computational Materials Science, Oct 1, 2023

Modelling of grain structure and segregation in casting

HAL (Le Centre pour la Communication Scientifique Directe), Sep 28, 2005

International audienc

Cellular Automaton - Finite Element Modeling of Solidification Grain Structures - Extensions for Welding Processes

HAL (Le Centre pour la Communication Scientifique Directe), May 20, 2013

Cellular Automaton (CA) - Finite Element (FE) modeling is an efficient way to simulate the nuclea... more Cellular Automaton (CA) - Finite Element (FE) modeling is an efficient way to simulate the nucleation and growth of solidification grain structures in the context of casting processes. The methodology is reported to reach predictions for competition between columnar and equiaxed grain structures [1], coupling with microsegregation due to diffusion of species [2], macrosegregation due to fluid flow [3] and solid transport [4]. Recent comparisons with in-situ and real time x-ray radiography observations of solidifying alloys have also reported the current limits of the model and the need for more systematic characterizations of benchmark experiments [5]. One of the limits currently faced is the possibility to predict grain structures for large cast parts. While CAFE simulations can deal with volume sizes that are typical of the investment casting process [6], it requires extensions for other processes. The present keynote will list the efforts recently made to overpass this difficulty. They are based on parallel computations and dynamic allocation strategies in order to focus the computation resources in the region of the mushy zone. While the above progresses were necessary, they did not permit to handle simulation of the grain structure during welding processes. This is due to the fact that the coupon contains an initial grain structure that must be known at all locations and at any time in order to compute its local melting and the epitaxial growth from partially melted grains, typical of the solidification of the weld pool. A solution is presented in the present paper that permits simulation of multiple passes in welding processes for large computational domains. This achievement allows for grain structure manufacturing in welding processes and remelting surface treatments, as show in the figure below.

Modeling of Microstructural Evolution during Friction Stir Welding Applied to AA2024 Aluminum Alloys to Predict the Weld Mechanical Properties

HAL (Le Centre pour la Communication Scientifique Directe), Mar 15, 2015

International audienceFriction stir welding on aluminum alloy is seen as an alternative solution ... more International audienceFriction stir welding on aluminum alloy is seen as an alternative solution to riveting 2024 and 7075 aluminum alloys pieces in order to lighten aircraft structure. On these alloys, mechanical properties are linked to structural hardening due to solid state precipitation. A coupling approach is proposed in order to manage the precipitates distribution evolution taking place during the process and predict final properties. At macro-scale, a model is used to get the thermal evolution in the different parts of the welded zone. At micro-scale, a time-efficient precipitation simulation is developed based on a reliable thermodynamic description. A particle size distribution approach (PSD) is proposed to predict the nucleation, growth, dissolution and coarsening of stable and metastable phases. An accurate yield strength model is applied on the final distribution. Calibration is performed on differential scanning calorimetry studies (DSC), hardening test and tensile tests for both isothermal, non-isothermal and weld samples

Microstructure Modeling

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Sep 23, 2016

Analytical multicomponent microsegregation model for equiaxed globular growth with diffusion interaction between species

HAL (Le Centre pour la Communication Scientifique Directe), Jul 8, 2014

In casting processes, the development of one solid phase from the liquid gives rise to microsegre... more In casting processes, the development of one solid phase from the liquid gives rise to microsegregation. The liquid is enriched in solute species that diffuse to/from the solid/liquid interface. In multicomponent alloys, this enrichment mainly controls the solidification path and plays a major role for the estimation of the nature and amount of secondary phases. While numerical models usually rely on few approximations [1], analytical models also remain of interest for coupling with large scale simulations of casting processes [2]. Several models have been proposed to predict microsegregation [3]. However, very few models have been applied to multicomponent alloys and coupled with thermodynamic equilibrium calculations [4]. Moreover, interaction between species (or cross diffusion phenomena) is always neglected. We propose an analytical solution for a multicomponent microsegregation model with interaction between species. This paper relies on the approximation developed by Martorano et al. [3] initially proposed for binary alloys. The model is coupled with an energy balance and applied to simulate globulitic grain solidification in a ternary alloy during a cooling process. The influence of the cross-diffusion terms in the liquid diffusion matrix is demonstrated. A comparison is also provided with an exact solution using a front tracking method. References [1]Q. Chen, B. Sundman, Materials Transactions 43 (2002) 551-559 [2]H. Combeau, M. Zaloznik, S. Hans, P.-E. Richy, Metall. Mater. Trans. B 40 (2009) 289-304 [3]M.A. Martorano, C. Beckermann, Ch.-A. Gandin, Metall. and Mater. Trans. A 34 (2003), 1657-1673, 35A (2004) 1915 [4]H. Zhang, Ch. A. Gandin, H. Ben Hamouda, D. Tourret, K. Nakajima, J. He, ISIJ International 50 (2010) 1859-1866

Materials & Design, Dec 1, 2016

The GP(I) zone formation during quench is simulated in an industrial Aluminum alloy AA7449 75 mm ... more The GP(I) zone formation during quench is simulated in an industrial Aluminum alloy AA7449 75 mm thick plate by using a multi-class precipitation model. For this purpose, results of in situ SAXS experiments are reported. A methodology is presented that takes advantage of the collected data to derive i -a thermodynamic description for GP(I) zones from reversion heat treatments by using a solubility product and ii -the influence of excess vacancies on diffusion coefficients. This approach allows reproducing reasonably well the GP(I) zone formation measured during rapid cooling. Further, the simulated as-quenched surface yield strength compares well with experimental results reported in the literature.

Computation of Phase Transformation during Welding Processes

HAL (Le Centre pour la Communication Scientifique Directe), May 15, 2012

International audienc

Microstructural evolution during friction stir welding on AA2024 aluminium alloys - Application to the prediction of the mechanical properties

HAL (Le Centre pour la Communication Scientifique Directe), Sep 27, 2015

International audienceFriction stir welding on aluminium alloys is seen as an interesting option ... more International audienceFriction stir welding on aluminium alloys is seen as an interesting option to lighten aircraft structure. In particular, this process is considered as an alternative to the standard riveting process used for joining stiffeners to panels. However in aluminium alloys, mechanical properties are linked to structural hardening due to solid state precipitation. This phenomenon is known to affect the final properties of the welds after FSW. Thus the estimation of precipitate evolutions is of prime importance in order to deliver reliable welds to the aircraft industry. A time-efficient solid-state precipitation modelling for aluminium alloys based on a reliable thermodynamic description has been developed. A particle size distribution approach (PSD) is proposed for multi-components alloys to predict the nucleation, growth, dissolution and coarsening of both stable and metastable phases. At a larger scale, a macro-structural model is used to define precisely the thermo-mechanical evolutions of the metal parts. It allows to know the thermal evolution during the whole FSW process. Then, it is possible to couple the models in order to define precisely the precipitate evolutions in HAZ, TMAZ and nuggets domains leading to heterogeneous mechanical properties. Thereafter an accurate yield strength model is developed knowing the final precipitate radius distribution and precipitates properties. The calibration of this model is performed on differential scanning calorimetry studies (DSC), hardening test and tensile tests for both isothermal / non-isothermal treatments. This microstructural model is applied on a 2024-T3 aluminium alloy. The final mechanical properties are presented and discussed

IOP conference series, May 29, 2019

Modeling and experimental characterization of the microstructure and grains structure of Al-7wt%Si directionally solidified

HAL (Le Centre pour la Communication Scientifique Directe), Sep 27, 2010

Elsevier eBooks, 2022

1. Introduction 2) Directional solidification and related defects 2.1) Generalities on the castin... more 1) Introduction 2) Directional solidification and related defects 2.1) Generalities on the casting processes 2.1.1) The Bridgman-Stockbarger casting process 2.1.2) Alternate casting processes 2.2) Casting defects 2.2.1) Crystal structure 2.2.2) Microstructure and microsegregation 2.2.3) Freckles 2.2.4) Deformation related defects 3) Heat treatments and microstructure optimizations 3.1) Generalities on heat treatments 3.1.1) Solution heat treatment 3.1.2) Aging heat treatments 3.2) Defects and optimizations 3.2.1) Incipient melting 3.2.2) Optimizations 4) Mechanical properties sensitivity to the processing parameters 4.1) Creep and tensile properties 4.2) Fatigue properties 5) Conclusions References

npj Microgravity

Space levitation processing allows researchers to conduct benchmark tests in an effort to underst... more Space levitation processing allows researchers to conduct benchmark tests in an effort to understand the physical phenomena involved in rapid solidification processing, including alloy thermodynamics, nucleation and growth, heat and mass transfer, solid/liquid interface dynamics, macro- and microstructural evolution, and defect formation. Supported by ground-based investigations, a major thrust is to develop and refine robust computational tools based on theoretical and applied approaches. This work is accomplished in conjunction with experiments designed for precise model validation with application to a broad range of industrial processes.

Thermomechanical analysis of the solidification of fused cast alumina-zirconia-silica refractory blocks

IOP Conference Series: Materials Science and Engineering

Cooling history of fused cast Alumina-Zirconia-Silica (AZS) refractory blocks is recorded with th... more Cooling history of fused cast Alumina-Zirconia-Silica (AZS) refractory blocks is recorded with thermocouples. Postmortem investigations are performed including hot tears. Discussion about solidification path is done with the purpose to better understand phenomena occurring during casting. Heat transfer simulations are compared with recorded temperature histories. Mechanical outputs from THERCAST® are analyzed, revealing the possibility to calibrate the risk of hot tears formation by considering a cumulated strain based criterion.

International Journal of Thermal Sciences, 2021

Thermal contact resistance between two adjacent materials is one of the major concerns in a large... more Thermal contact resistance between two adjacent materials is one of the major concerns in a large variety of practical situations in heat transfer. The presence of this resistance yields a temperature jump across the interface. Due to this discontinuity, numerical modelling of thermal contact resistance runs into difficulties. In this work, we propose a simple and efficient numerical model to account for thermal contact resistance at immersed interfaces in multi-material heat transfer. The present model is based on the diffuse interface method. The effect of contact resistance between two adjacent materials is accounted for in the mixing laws of the thermal conductivity and the heat capacity. The model is validated through different test cases, including both steady and unsteady conduction, and applied to simulation of chill cooling and solidification of a steel sample on board the International Space Station.

Computers & Fluids, 2019

The oscillation of a levitated drop is a widely used technique for the measurement of the surface... more The oscillation of a levitated drop is a widely used technique for the measurement of the surface tension and viscosity of liquids. Analyses are mainly based on theories developed in the nineteenth century for surface tension driven oscillations of a spherical, force-free, liquid drop. However, a complete analysis with both analytical and numerical approaches to study the damped oscillations of a viscous liquid drop remains challenging. We first propose in this work an extension of the theory that includes the coupled effects of surface tension and viscosity. The analytical solution permits derivation of both properties simultaneously, which is of interest for fluid with unknown viscosity. Then, the robustness of an Eulerian framework to simulate the fluid flow is discussed. Simulations of different oscillations modes for a liquid iron droplet immersed in a low density gas and comparisons with the derived theory are detailed and presented.

Materialia, 2018

Competitive grain growth during the directional solidification of a polycrystalline binary alloy ... more Competitive grain growth during the directional solidification of a polycrystalline binary alloy is investigated by performing systematic three-dimensional large-scale phase-field simulations with the GPU supercomputer TSUBAME2.5 at the Tokyo Institute of Technology. Contrary to two-dimensional investigations, in which an unusual growth of unfavorably oriented (UO) grains has been observed frequently in preference to favorably oriented (FO) ones, the grain selection in the present three-dimensional simulations follows essentially the Walton and Chalmers model, in which FO grains are predominant. The UO dendritic grains persist for longer times than the UO cellular grains, and the FO dendritic grains remain smaller than the FO cellular ones. The change in the number of grains follows a power law, with an exponent that is much lower than that of the Kolmogorov's model describing a purely geometrical growth selection.

IOP Conference Series: Materials Science and Engineering, 2016

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Numerical Simulation of Solidification, Homogenization, and Precipitation in an Industrial Ni-Based Superalloy

Metallurgical and Materials Transactions A, 2016

AbstractA comprehensive simulation approach integrating solidification, homogenization, and preci... more AbstractA comprehensive simulation approach integrating solidification, homogenization, and precipitation during aging has been used to predict the formation of γ/γ′ microstructures in the AM1 nickel-based superalloy. The particle size distribution of intradendritic γ′ precipitates after aging was calculated with a multicomponent diffusion model coupled with CALPHAD thermodynamics for the equilibrium at the interface. The influence of residual microsegregation after homogenization and quenching was analyzed through different initial conditions obtained from calculations of the concentration profiles in the primary γ dendritic microstructure during solidification and the homogenization heat treatment. While the global sequence of precipitation remains qualitatively the same, substantial differences in the final volume fraction of γ′ precipitates were predicted between the core and the periphery of a former dendrite arm, for typical homogenization and aging conditions. To demonstrate the relevance of the developed simulation approach, the model was also used to investigate modified precipitation heat treatments. The simulations showed that relatively short heat treatments based on slow continuous cooling could potentially replace the extended isothermal heat treatments which are commonly used. Slow continuous cooling conditions can lead to similar γ′ precipitates radii and volume fractions, the main differences with isothermal heat treatments lying in a narrower particle size distribution.