Coupled Cellular Automaton (CA) - Finite Element (FE) Modeling of Directional Solidification of Al-3.5 wt% Ni Alloy: A Comparison with X-ray Synchrotron Observations - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue ISIJ international Année : 2014

Coupled Cellular Automaton (CA) - Finite Element (FE) Modeling of Directional Solidification of Al-3.5 wt% Ni Alloy: A Comparison with X-ray Synchrotron Observations

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Résumé

Development of dendritic grain structure and mesa-segregation leading to localized intergranular eutectic is simulated during directional solidification of an Al - 3.5 wt% Ni alloy with two pulling velocities (4 mu m s(-1) and 8 mu m s(-1)) using a two-dimensional (2D) Cellular Automaton Finite Element (CAFE) model. 2D CAFE simulations are compared with in situ and real-time experiments characterized by means of X-ray radiography at the European Synchrotron Radiation Facility (Grenoble, France). Two nucleation models are used. The first model is established by listing all measured positions and orientations of experimentally-observed nucleation events. The undetermined value of the nucleation undercooling is then set to 0 degrees C for all nucleation sites. The other model considers a stochastic model with a Gaussian distribution of the nucleation site as a function of the undercooling. It is derived from series of experiments. The influences of the nucleation models and liquid convection on the grain structure characteristics are numerically investigated. A good agreement with experimental observations is achieved concerning the evolutions of both the dendritic and the eutectic growth fronts (i.e., the size of the mushy zone). The predicted grain size and elongation are compared with measurements for the two nucleation laws. Simulations using the list of nucleation events reach better agreement with the longitudinal profiles of the grain equivalent diameter and elongation factor compared to the stochastic nucleation model. Direct tracking of the eutectic growth front as well as three-dimensional analyses are found to be required for improvement of the predictions.

Dates et versions

hal-00974728 , version 1 (07-04-2014)

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Dong Rong Liu, Guillaume Reinhart, Nathalie Mangelinck-Noël, Charles-André Gandin, Henri Nguyen-Thi, et al.. Coupled Cellular Automaton (CA) - Finite Element (FE) Modeling of Directional Solidification of Al-3.5 wt% Ni Alloy: A Comparison with X-ray Synchrotron Observations. ISIJ international, 2014, 54 (2 - Special Issue on Cutting Edge of Computer Simulation of Solidification, Casting and Refining), pp.392-400. ⟨10.2355/isijinternational.54.392⟩. ⟨hal-00974728⟩
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