The Three-Dimensional Simulation Research Of Binary Alloy Dendritic Growth Based On PF-LBM

The solidification microstructure of materials is a three-dimensional structure. In the research of microstructure integrated information, it is incomplete or even wrong using two-dimensional simulation information to represent the three-dimensional structure. The dendritic crystal is a common organization phenomenon in the process of solidification, it’s process of growth always accompanied by melt flow, The melt flow have a direct effect on the transmission of momentum, mass and heat which change the morphology of dendritic crystal’s growth. So there is important guiding significance to study the relationship between the flow field in three dimensional space and the growth of dendritic crystal.The paper is coupling three dimensional Lattice Boltzmann model with three-dimensional dendrite growth phase field model based on the KKS. Build dendrite isothermal growth under forced convection environment three-dimensional PF-LBM model.We studied the three dimensional dendrite growth behavior when there is coupling with the force flow field based on Al-Cu alloy. And analyzed the relationship between evolution form of three dimensiona dendrites and velocity,super-cooling degree, anisotropy, and the composition of Cu.We compared the result of three-dimensional simulation with two-dimension and morphology of dendritic crystal’s growth got from experiment. The results showed that:Forced convection makes the three-dimensional dendrite growth of tilting, incident flow side grow faster than the back flow side;Solute at the interface front distributed of tilting,solute diffusion layer of incident flow side is less than the flow back side, solute are mainly distributed in the back side of flow back side. When the velocity is larger, the tilting growth appearance of dendrite is more obvious; Isoconcentration line in the interface of the incident flow side is dense, dendrite tip of the solute is lower, dendrite growth is faster; Isoconcentration line in the interface of the flow back side is sparse,dendrite tip of the solute is higher, dendrite growth is lower.The larger supercooling,the quicker of the dendrite tip velocity,solid phase of the solute is higher;the solute isoconcentration line of the incident flow is dense,dendrite tip of the solute is higher;the solute isoconcentration line of the flow back is sparse,dendrite tip of the solute is volatility.There is coupling with the flow field,the greater the strength of anisotropy,the every main dendrite arm is thinner,the faster the dendrite growth;The greater the initial composition of Cu, the slower the dendrite growth,thesparser the isoconcentration line in the interface, the higher of the solid solute concentration and the interface between the solute concentration. The flow simulation of liquid metal in three-dimensional is complex than in the two-dimensional simulation,the influence to the evolution of dendrite caused by flow is obvious than the situation in two-dimensional.The simulation results of three dimension in this paper match well with the dendrite growth morphology in experimental results which show that the accurate of the model simulation results.