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Significance Statement
Coupling between 3D-phase field modelling of multicomponent alloy microstructures and fluid flow simulations presents an important contribution to the still developing and improving field of computational simulation of casting processes in an ICME framework. Besides the methodological aspects, the study also gives new knowledge and insights on the cross-permeability of the interdendritic zone and highlights the opportunities offered by simulation approaches: By direct simulation of the dendrite morphology and its change through the mushy zone, and by a systematic variation of the primary dendrite distance in the phase-field simulations, the dependency of the effective cross-permeability on the fraction liquid and the effect of the primary dendrite distance could be quantitatively evaluated for the technical Ni-base alloy 718 and compared to empirical relations from literature.
The study not only presents a methodology how to link different software tools and exchange data between them, but also proposes a way how to aggregate detailed results on the microscale and transform them by systematic variation and averaging into empirical laws which can be applied on the macroscale.
Journal Reference
JOM, 2016, Volume 68, Issue 1, pp 27-36.
Böttger1, C. Haberstroh2, N. Giesselmann2
[expand title=”Show Affiliations”]- Access e.V, 52072, Aachen, Germany
- Institut für Industrieofenbau und Wärmetechnik, RWTH, 52072, Aachen, Germany
Abstract
Based on the results of microstructure simulations, fluid flow through the semisolid region during directional solidification of the technical Ni-base alloy 718 has been studied. Three-dimensional microstructures at different positions in the semisolid region were obtained by using a multicomponent multiphase-field model that was online coupled to a commercial thermodynamic database. For the range of five different primary dendrite distances λ 1 between 50 µm and 250 µm, the flow velocity and the permeability perpendicular to the dendrite growth direction was evaluated by using a proprietary Lattice-Boltzmann model. The commercial CFD software ANSYS FLUENT was alternatively applied for reference. Consistent values of the average flow velocity along the dendrites were obtained for both methods. From the results of the fluid flow simulations, the cross-permeability was evaluated as a function of temperature and fraction liquid for each of the five different primary dendrite distances λ 1. The obtained permeability values can be approximated by a single analytical function of the fraction liquid and λ 1 and are discussed and compared with known relations from the literature.
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