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Andrew Mullis (University of Leeds)18/06/2019, 10:30HighlightThe fragmentation of dendrites immediately following the recalescence phase of growth during the solidification of undercooled melts has been invoked to explain various rapid solidification microstructures. Despite this, little direct evidence of such a fragmentation process usually survives in the as-solidified material. We report on the rapid solidification of the single phase, congruently...Go to contribution page
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Marcus Reinartz (Friedrich-Schiller-Universitรคt Jena)18/06/2019, 10:50Oral PresentationExperiments on the International Space Station (ISS) lead to the idea of a special growth mechanism in Al-rich Al-Ni melts. Previous analyses of dendrite growth velocity as a function of undercooling in these alloys showed anomalous behaviour, particularly a decreasing velocity for increasing undercoolings [1]. The experiments on the ISS reproduced the results obtained on earth but with an...Go to contribution page
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Prof. Surendra Tewari (Cleveland State University)18/06/2019, 11:10Oral PresentationUnder a NASA (National Aeronautics and Space Agency)-ESA (European Space Agency) collaborative research project, MICAST (Microstructure formation in casting of technical alloys under a diffusive and magnetically controlled convection conditions), three Al-7wt% Si samples (MICAST-6, MICAST-7 and MICAST2-12) were directionally solidified at growth speeds varying from 10 to 50 ฮผm s-1 aboard the...Go to contribution page
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Shuangming Li (Northwestern Polytechnical University)18/06/2019, 11:30Oral PresentationFeathery grains have attracted considerable research interest since they were first observed in semi-continuous casting of industrial aluminum alloys about 70 years ago. Different from the regular columnar or equiaxed morphologies observed in alloy castings, this special crystal structure exhibits the alternant twinned and untwinned lamellae morphology. Previous studies focus on the analysis...Go to contribution page
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Qing Cai (BCAST)18/06/2019, 11:50Oral PresentationTraditional aluminium casting alloys are based on binary eutectic systems with additions of minor alloying elements for improved castability and mechanical properties. The increasing demand for high strength aluminium casting alloys has led to several studies of ternary eutectic aluminium alloy systems, such as Al-Si-X (X = Sn, Ge, Cu) for the formation of bulk nano/ultrafine composite...Go to contribution page
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Natalia Shevchenko (Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany)18/06/2019, 13:30KeynoteX-ray radioscopic studies have been performed to improve the understanding of the complex interrelation between melt flow and the evolution of dendritic structures during solidification of Ga-In alloys. Natural convection is caused by density variations within the solidifying alloys. Forced convection was produced by electromagnetic stirring. Within this work special interest was focused on...Go to contribution page
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Virkeshwar Kumar (Indian Institute of Technology Bombay)18/06/2019, 14:00Oral PresentationThermal diffusivity and individual solutal diffusivity of component play a significant role during natural convection dominated solidification of multicomponent alloys. In this study, in situ experimental observations of solidification of a ternary salt solution (water-potassium nitrate-ammonium chloride) are reported. The phase diagram of the ternary salt solution consists of three distinct...Go to contribution page
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Kate Elder (Northwestern University)18/06/2019, 14:20Oral PresentationDendrites are ubiquitous structures that are central to setting material properties but the mechanism behind how dendrites grow is not fully understood. After x-ray synchrotron radiation experiments are performed, the dendritic growth of Al-12.6wt%Cu alloys is studied in 4-dimensions to track the evolution of the 3-dimensional structure as a function of time using novel x-ray tomography...Go to contribution page
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Fatima Mota (IM2NP UMR CNRS 7334)18/06/2019, 14:40Oral PresentationThe microstructure formed during the solidification processing from the melt is a critical issue for industrial applications. Most of the mechanical properties of alloys are a result of these microstructures. Understanding and predicting both the microstructure formation and evolution are crucial for the development of performant materials. Since microstructures are strongly influenced by the...Go to contribution page
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Tong Zhao Gong (Institute of Metal Research, Chinese Academy of Sciences)18/06/2019, 15:00Oral PresentationThe growth dynamics of multiple equiaxed dendrites in a thin metallic sample is studied using *in situ* synchrotron X-ray imaging of Al-4 wt.%Cu alloy solidification experiments and corresponding full-scale three-dimensional (3-D) phase-field (PF) simulations. The tip growth velocity *V*, tip radius *ฯ*, the secondary dendritic arm spacing (SDAS) *ฮป*$_2$ and the total solid fraction *f*$_s$,...Go to contribution page
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Martin Glicksman (Florida Institute of Technology)18/06/2019, 16:10HighlightObservations of melting crystallites in microgravity showed unusual shape changesas melting proceeded toward extinction. When re-analyzed in 2011, shape evolution data showedneedle-like crystallites becoming spheroids as they melted toward extinction, suggesting thatsome type of capillary phenomenon at solid-liquid interfaces was responsible for an energy releasecapable of...Go to contribution page
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Hieram Neumann-Heyme (Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics)18/06/2019, 16:30Oral PresentationThe quantitative prediction of dendrite fragmentation has remained a major issue in the modeling of solidification processes. A systematic approach to this issue is presented that consists of two parts. First, a thorough analysis is carried out of existing and new experimental data. A suite of different image processing techniques is developed that allows for obtaining robust statistics of the...Go to contribution page
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Peter Bollada (University of Leeds)18/06/2019, 16:50Oral PresentationMolecular dynamic simulations, ab initio (DFT) calculations and experimental evidence suggests that there is a liquid-solid transition region which may be characterised by an order parameter. In this interface region the order parameter is not observed to be symmetrical, rather it tends to be steep on the solid side and exponentially decreasing on the liquid side. The order parameter in phase...Go to contribution page
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207. PHASE-FIELD MODELLING OF NON-EQUILIBRIUM SOLIDIFICATION BY THE THERMODYNAMIC EXTREMAL PRINCIPLEHaifeng Wang (tate Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University)18/06/2019, 17:10Oral PresentationModelling of non-equilibrium solidification is of singular importance in microstructure control, which however owing to the complex systems with complex additional constraints is still an open problem. In this work, the thermodynamic extremal principle was applied to solve the complex additional constraints self-consistently in thermodynamics for both binary and multi-component alloys....Go to contribution page
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Peter Galenko (Friedrich Schiller University of Jena)18/06/2019, 17:30Oral PresentationKinetics of crystal growth in undercooled melts is analyzed by methods of theoretical modeling. Special attention is paid to rapid growth regimes occurring at deep undercoolings at which non-linearity in crystal velocity appears. A traveling wave solution of the phase eld model (PFM) derived from the fast transitions theory is used for a quantitative description of the crystal growth...Go to contribution page
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Tadej Dobravec (Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana, Slovenia)19/06/2019, 10:30HighlightA two dimensional model for the simulation of dendritic growth in binary alloys is developed. Phase field model is used to derive the system of partial differential equations describing the temporal evolution of the solid-liquid interface and concentration field. Quantitative modeling is assured by the use of thin interface limit of the isothermal phase field model. Meshless local radial basis...Go to contribution page
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Jinglian Du (Tsinghua University, Northwestern Polytechnical University)19/06/2019, 10:50Oral PresentationThe 3-D morphology, orientation selection and behind mechanism of magnesium alloy dendrite were investigated by performing multiscale mathematical simulations. The results showed that the ฮฑ-Mg dendrite prefers to grow along <11-20> basal direction and <11-23> nonbasal direction, and the resultant 3-D dendritic morphology exhibits a typical 18-primary branch pattern. Such dendritic...Go to contribution page
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Jean-Marc Debierre (IM2NP, Aix-Marseille University)19/06/2019, 11:10Oral PresentationExperiments performed in the International Space Station have evidenced oscillatory modes for the solidification of a succinonitrile-based transparent alloy. These oscillations have been studied by phase-field numerical simulations that allowed a better understanding of their origin [1-2]. A recent re-examination of the experimental data showed that, depending on the misorientation of the...Go to contribution page
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Eisuke Miyoshi (Kyoto Institute of Technology)19/06/2019, 11:30Oral PresentationGrain growth, a competitive growth of crystal grains that occurs after or simultaneously with solidification, is one of the most important phenomena in controlling the microstructure of polycrystalline materials. The fundamental process underlying grain growth is the migration of grain boundaries; thus, the growth behavior is largely dominated by the properties (energy and mobility) of grain...Go to contribution page
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Guillaume Boussinot (Access e.V.)19/06/2019, 11:50Oral PresentationAdditive manufacturing by Laser Powder-Bed Fusion (LPBF) is accompanied by solidification under large thermal gradients and cooling rates. As a consequence, solidification morphologies between dendritic with only limited sidebranches or rather cellular pattern are commonly observed. The growth regime is characterized by Pรฉclet numbers of order or larger than 1 (with cell tip radii of order or...Go to contribution page
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Yi Feng (Department of Materials Science and Engineering, McMaster University, Canada.)19/06/2019, 13:30KeynoteA 3D meso-scale discrete-element model has been developed to simulate ๏ฌuid ๏ฌow during dendritic solidi๏ฌcation of steel. The model domain is a representative volume element consisting of a set of equiaxed dendritic grain envelopes along with extra-dendritic liquid channels, where the ๏ฌnal grain shape is given by a Voronoi tessellation. Solidi๏ฌcation of each grain is simulated via a volume...Go to contribution page
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Damien Tourret (IMDEA Materials)19/06/2019, 14:00Oral PresentationIn this talk, we will review recent developments using the multiscale Dendritic Needle Network (DNN) approach for dendritic growth, with a particular emphasis on its application to convective transport in the liquid phase. The DNN method was developed for the modeling of dendritic growth of hierarchical needle-like dendritic crystals, which typically form at low solute supersaturation or...Go to contribution page
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Alexandre Viardin (ACCESS e.V.)19/06/2019, 14:20Oral PresentationMesoscopic envelope models rely on the description of the complex morphology of a dendritic grain by an envelope, which is a smooth surface connecting all of the dendrite tips. This simplification in the description of the grain shape enables to reduce requirements on spatial resolution and allows for modelling of larger number of grains or domains, when compared to more detailed microscopic...Go to contribution page
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Abdellah kharicha (Montunivesitรคt leoben)19/06/2019, 14:40Oral PresentationThe last decade has witnessed the development of various solidification models based on volume averaging methods. To reduce the calculations cost, the averaging reduces information contained within the mushy zone to a single variable, the solid volume fraction. The solidification rate and the permeability are then calculated with the help of closure laws often based on some semi-empirical...Go to contribution page
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Laszlo Sturz (Access e.V.)19/06/2019, 15:00Oral PresentationMultiple dendritic equiaxed grain formation is common to solidification in many technical alloys in industrial solidification processes. We investigate this type of grain formation and competition during directional solidification of grain-refined Al-3.5wt.-%Ni at various solidification conditions by comparison of experimental data and 3D dendrite needle network (DNN) modeling. For the...Go to contribution page
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ANTONIO OLMEDILLA (INSTITUT JEAN LAMOUR)19/06/2019, 15:20Oral PresentationA 3D mesoscopic envelope model is used to numerically simulate the experimental X-ray observations of the equiaxed dendritic isothermal solidi๏ฌcation of a thin sample of Al-20 wt%Cu alloy including the natural convection ๏ฌow. Several four-grain simulations are run to investigate the e๏ฌect of the convection, of the grain position, and of the grain rotation on the tip growth kinetics of one of...Go to contribution page
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Tomohiro Takaki (Kyoto Institute of Technology)20/06/2019, 10:30HighlightFormation process of equiaxed structure is quite complicated phenomenon. The most difficult point in the modeling of the equiaxed structure formation process would be a motion of dendrites. In our previous study, we succeeded in expressing the growth of a single dendrite accompanying the motion by coupling phase-field method, lattice Boltzmann method, and equations of motion [R. Rojas, T....Go to contribution page
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Yukinobu Natsume (Akita University)20/06/2019, 10:50Oral PresentationIn this study, a numerical model was developed, and direct simulations were performed to predict solidification grain structures and macrosegregation based on a threedimensional cellular automaton finite difference (CAFD) method coupled with flow calculation of natural convection and shrinkage flow. First, to evaluate the model coupled with natural convention, simulations of unidirectional...Go to contribution page
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Yun Chen (Institute of Metal Research, Chinese Academy of Sciences)20/06/2019, 11:10Oral PresentationThe existence of oxide inclusions (e.g. Al2O3) in the steel melt is unavoidable. Most of these nonmetallic inclusions come from the steel-making process. During solidification, some of these inclusions remain in the melt and interact with melt flow and the growing crystals. The movement of solid oxide inclusions in steel melt is directly numerically simulated through coupling the solid...Go to contribution page
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Alain Jacot (BCAST, Brunel University London)20/06/2019, 11:30Oral PresentationGrain refinement of metallic alloys is of critical importance to minimize the risk of solidification defects and obtain the desired mechanical properties. The effectiveness of grain refinement depends strongly on the interplay between potency of nucleant particles for heterogeneous nucleation and their ability for grain initiation. For a given alloy, the former is an inherent property of the...Go to contribution page
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Ang Zhang (Tsinghua University)20/06/2019, 11:50Oral PresentationThe interaction between the capillarity and the thermal-solute-convection fields determines the microstructure evolution during solidification, which significantly influences the eventual mechanical properties of materials. However, to achieve the coupled thermal-solute-convection microstructure evolution with a realistic Lewis number (Le ~ 104) and Prandtl number (Pr ~ 10-2), the computing...Go to contribution page
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Christoph Beckermann (University of Iowa)20/06/2019, 13:30KeynoteThe simultaneous prediction of macrosegregation and columnar to equiaxed transition (CET) in metal casting is still an important challenge. One of the open questions is the role of melt convection on the CET and the effect of the CET on macrosegregation. A three-phase Eulerian volume-averaged model for macrosegregation and CET is developed. The model uses our recently-developed accurate...Go to contribution page
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Olga BUDENKOVA (CNRS UGA SIMAP)20/06/2019, 14:00Oral PresentationSince last century, two and three-phase models are generally adopted for the meso-scale simulations of the growth of equiaxed grains in solidification of binary and ternary alloys [1]-[3]. Yet, as far as three-phase models are concerned, their implementation in the macro-scale model with the equiaxed grains transport can be realised in different ways. Indeed, since the solid fraction of a...Go to contribution page
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Tao WANG (Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, P. R. China; Univ. Grenoble Alpes, CNRS, Grenoble INP, SIMAP, F-38000 Grenoble, France)20/06/2019, 14:20Oral PresentationA three-phase equiaxed solidification model where macroscale heat transfer and fluid flow are coupled with microscale nucleation and dendrite growth, is applied to the simulation of the macrosegregation in binary alloy solidification subjected to the electromagnetic stirring. The investigated experimental solidification case is conducted in a cavity which has a good control of the thermal...Go to contribution page
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Vincent Maguin (SAFRAN TECH - Mines ParisTech PSL)20/06/2019, 14:40Oral PresentationDuring casting, di๏ฌusion phenomena are often simpli๏ฌed by Lever-Rule or Gulliver-Scheil hypotheses, thus simplifying chemical di๏ฌusion to extreme con๏ฌgurations. The present work proposes an extension of the Tong-Beckermann microsegregation model to multi-component alloys while considering ๏ฌnite di๏ฌusion in liquid and solid phases plus the e๏ฌect of tip undercooling of the columnar front. The...Go to contribution page
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Stephan Jรคger (LKR Leichmetallkompetenzzentrum Ranshofen GmbH, Austrian Institute of Technology, Ranshofen, Austria)20/06/2019, 15:00Oral PresentationAn e๏ฌcient model for the prediction of dendritic grain growth is developed coupling the lattice Boltzmann method for solving the transport of solute and a cellular automaton algorithm for determining the evolution of grainsโ envelope and the release of solute during phase change. In contrast to solving equations from the ๏ฌeld of continuum mechanics the new model is more related to particular...Go to contribution page
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Mohammed M'Hamdi (SINTEF/NTNU)20/06/2019, 16:10Oral PresentationMacrosegregation refers to the inhomogeneous distribution of alloy elements at the macro scale in solidified castings. It is a common defect in direct chill (DC) casting of aluminium alloys. Since various transport phenomena contribute to the formation of macrosegregation, numerical modelling is a valuable tool to assess their role and study their interplay with process parameters. One such...Go to contribution page
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Benjamin Gerin (CNRS, Institut Jean Lamour)20/06/2019, 16:30Oral PresentationThe control of the carbon macrosegregation level in steel ingots is important for the structural integrity of the nal component. During solidication, the fragmentation of the columnar dendrites is an important source of equiaxed grains, and has a large in uence on the macrosegregation and the grain structure. The goal of this study is to show that a numerical model that takes into account...Go to contribution page
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JUN LI (Shanghai Jiao Tong University)20/06/2019, 16:50Oral PresentationThe formation of casting defects, including macrosegregation, shrinkage cavity, porosity, and inclusion, which resulting from the combined action of multi-physics filed, is a complex process. This process including the nucleation, growth, floating (or settling) of both inclusion and equiaxed crystals; growth and fragmentation of dendritic crystals; solidification shrinkage; solute...Go to contribution page
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Martรญn Matรญas Cisternas Fernรกndez (Universitรฉ de Lorraine, CNRS, IJL)20/06/2019, 17:10Oral PresentationWithin the framework of the ESA GRADECET project, experiments of directional solidication of cylindrical Ti-Al samples were conducted in hypergravity. The experiments were performed in a centrifuge with the apparent gravity (sum of centrifugal and terrestrial gravity) aligned along the cylinder centerline. 3D numerical simulations of aluminum macrosegregation in these samples are...Go to contribution page
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Mr John Coleman (Purdue University)20/06/2019, 17:30Oral PresentationIn this study, 3D flow fields, sump profiles and macrosegregation patterns are predicted for HDC slabs of an Alโ4.5 wt.% Cu alloy. Numerical simulations are used to provide initial estimates of these features and the influence of slab geometry for a constant inlet configuration. In general, the heat conduction across the slab thickness controls the sump depth and general macrosegregation...Go to contribution page
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Zhongming REN (Shanghai University)21/06/2019, 10:30HighlightDuring solidification of alloys with a temperature gradient in a stati magnetic field, the thermoelectric magnetic(TEM) force may be induced. The TEM force will produce convection in the molten metal and stress in the solid during the solidification. The convection and stress may play an important role in the formation of the micro-and macro-structures of the alloy. The influence of the...Go to contribution page
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YVES DU TERRAIL COUVAT (SIMAP LABORATORY)21/06/2019, 10:50Oral PresentationApplying magnetic field during solidification of metallic alloys process under high thermal gradient may influence drastically microstructures of solidified metal. In fact, Magnetic Lorentz forces due to the coupling of electromagnetic field with thermo-electric currents are acting on the movement of solid grains and on the movements of fluid around grains, which finally produce re-organized...Go to contribution page
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Haijie Zhang (University of Leoben)21/06/2019, 11:10Oral PresentationThe presence of small amount of the Fe in the Al-Si alloy causes the formation of the platelet-shaped Al5FeSi intermetallic phase, which is detrimental to the alloy mechanical properties. A series of directional solidification experiments on Al-Si-M alloy were performed under diffusion or controlled convection to study the interaction of fluid flow and the formation of the intermetallic phase...Go to contribution page
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Chuanjun Li (Shanghai University)21/06/2019, 11:30Oral PresentationThe rapid solidification processing is frequently used to fabricate novel microstructures. In this work, the formation of novel microstructures in two Al-Cu alloys, i.e. hypoeutectic Al-26wt%Cu and hypereutectic Al-45wt%Cu alloy, in a steady magnetic field (SMF) was investigated using the conventional quenching technique. It was found that the application of the SMF led to appearance of a...Go to contribution page
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JUN WANG (Northwestern Polytechnical University)21/06/2019, 11:50Oral PresentationSupercooled liquids may offer fascinating phenomena as compared with the normal state. In the case of supercooled paramagnetic liquids, completely different phenomena in high magnetic fields have be observed thanks to the high undercooling leading to higher magnetization and very strong magnetic coupling in the liquids. However, due to the restriction of the magnetic field intensity and...Go to contribution page
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Yuansheng Yang (Institute of Metal Research, Chinese Academy of Sciences)21/06/2019, 12:10Oral PresentationElectromagnetic effect produced in alloy melt and dendrite growth under the action of a pulsed magnetic field are researched by experimental and simulation. Simulation results show that alternating gradient electromagnetic forces act on the melt in front of the interface of the growing dendrites and the maximum electromagnetic force appears near the front of the solid/liquid interface, which...Go to contribution page
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