Cross-Permeability of the Semisolid Region in Directional Solidification: A Combined Phase-Field and Lattice-Boltzmann Simulation Approach

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 k 1 between 50 lm and 250 lm, 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 k 1 . The obtained permeability values can be approximated by a single analytical function of the fraction liquid and k 1 and are discussed and compared with known relations from the literature.

An ICME Process Chain for Diffusion Brazing of Alloy 247

“…This approach is implemented in the MICRostructue Evolution Simulation Software MICRESS® [13] and includes direct coupling to Calphad databases using efficient extrapolation algorithms [14,15] as well as other additional features which are detailed in [16,17]. This tool has been successfully used for simulations of phase transformations in a number of technical alloy systems [18][19][20][21]. The important and central role of applied microstructure simulations and their potential in ICME settings has already been demonstrated using this software tool [22].…”

Mesoscopic modeling of equiaxed and columnar solidification microstructures under forced flow and buoyancy-driven flow in hypergravity: Envelope versus phase-field model

“…This permeability is a property of the internal structure of a single dendrite and is therefore conceptually different from that of the mushy zone, which represents a property of a large ensemble of dendrites. While a large amount of experimental and modeling work has been done on permeability of mushy zones [32][33][34][35][36][37][38][39][40][41], no model of permeability of dendrite envelopes exists. We may speculate that it would need to account for anisotropy due to the branch directions and for more than one characteristic length scale; however this is out of the scope of this work.…”

Advent of Cross‐Scale Modeling: High‐Performance Computing of Solidification and Grain Growth

“…As shown above, our large‐scale phase‐field lattice Boltzmann simulation enabled multiple dendrite growth with melt flow. It may have a potential for computing the permeability for the flow in the realistic solidification structure with multiple dendrites.…”