Phase Field Simulation Of Dendritic Growth Of Alloy In A Turbulence Flow

The mechanical properties and service life of the casting is decided by themicrostructure formed during solidification. Understanding the influence law of liquidmetal flow on dendritic growth clearly is an effective way to foresee and control theproperties of the casting.The microstructure growth and evolution under equilibrium state can be researchedby the phase field method without tracking the complicated liquid-solid interface. Theinfluence of various parameters on the dendritic growth can be simulated qualitativelyby the phase field model coupling with other model, such as interface fluctuations,undercooling, anisotropy, dynamic effects, and so on.Based on the improved KKS model, the influence of undercooling and metal meltflow on the dendritic growth and solute field distribution during isothermalsolidification of Al-2.5%Cu alloy under a turbulence flow is simulated by the phasefield model coupled with flow field model and solute field model.The momentum and mass conservation equation are solved by using the Simplealgorithm, The phase field, solute field and k-equation are solved by using the FiniteDifference method. The discrete equations is solved by vc++program, The Originsoftware is used to declare the data. At last, the results are analysised.The results show that the dendritic growth and solute field distribution ofsolidification process are serious effected by turbulence flow. The dendritic growth oflateral branch is induced at the reason of interface fluctuations caused by the turbulenceprinciple. The effect of disturbance is enlarged by anisotropic, which limit the freedomgrowth of dendritic tip and promote the speed of dendritic growth. The turbulence flownot noly destroy the symmetry morphology of dendritic, but also increase the velocityof dendritic growth on upstream. On account of turbulence flow, the concentration ofliquid solute and the radius of curvature on upstream is getting smaller, while thedownstream dendritic growth is limited, the concentration of solid solute and the radiusof curvature is getting larger. With the increase of turbulence flow velocity, the velocityof the upstream dendritic growth is larger, and the morphology is more developed, while the radius of curvature is getting smaller, and the solute diffusion layer of liquid-solidinterface is getting thinner. The concentration of liquid solute is getting lower, while theconcentration of solid solute is getting higher. Compared with upstream, there areopposite changes of morphology, the velocity of dendritic growth, the radius ofcurvature, the concentration of liquid solute and the concentration of solid solute islower on the downstream. The velocity of dendritic growth is slower, and the secondaryarms of solidification dendritic are better developed with the increase of undercooling.Correspondently, the concentration of solid solute and the solute segregation insolid-liquid interface decrease.