Study On The Effect Of Phase Field Parameters On Dendrite Growth Of Ni-Sn Alloy By Phase Field Method

Dendrite morphology in the microstructure of metal materials is one of the important factors affecting metal properties.In the process of metal solidification,there are factors such as heat and mass transfer,mechanics,and so on that can affect the nucleation and dendritic growth of metal microstructure,and there are also problems of high temperature and short time,which makes traditional experimental research very difficult.People hope to find a method that can simulate the solidification evolution process of more real metals.With the rapid development of computer technology,people associate materials with computers,providing a better method for studying the microstructure of metals.The phase field method is one of the computer simulation methods.The phase field method can reduce the problems that arise when tracking interface changes,simplify measurement methods,and have a high degree of adaptability to various structural changes.Due to the above advantages,it has become a major means of studying microstructure growth.The phase-field method is mainly based on the study of the Ginzburg-Landau phase and uses the differential equations created to show the combined effect of diffusion and thermodynamic driving,which is expressed by the introduction of the order parameters φ in the metallic congealing process,φ=1 to represents the solid phase in the process of solidification of metals;φ=0 to represent the liquid phase in the metal solidification;and 1>φ>0 to represent the solid-liquid coexistence in the metal solidification.Using the coupling effect of phase field,temperature field,and solute field,a set of equations capable of reacting and simulating the microstructure and evolution process is constructed to better reflect the real state of solidification of metal materials.In this paper,the phase field method is used to study the dendritic growth of Ni-Sn alloys.This article first introduces the development of phase field method at home and abroad,phase transformation theory,and phase field simulation models.Using entropy increasing functional and its thermodynamic laws as the basic theory,a thermodynamic consistent phase field simulation model for binary alloy solidification process is constructed.Anisotropic parameters,thermal diffusion parameters,and coupling parameters are introduced into the model,thereby deriving the phase field The governing equations for the interaction between the temperature field and the solute field.The phase field model is used to numerically simulate the dendritic growth of Ni-Sn alloy.The effects of anisotropic strength parameters,thermal diffusion parameters,and coupling parameters on the morphology and growth velocity of the arm tip during the dendritic growth process are studied using a controlled variable method.The simulation results are analyzed and the following conclusions were obtained:1)Both the tip growth rate of dendrites and the number of secondary branching arms production increase with increasing anisotropic strength parameters.2)An increasing thermal diffusion factor inhibits the growth of the branching tip and secondary branching arm of the dendrite.3)The increase of coupling parameters makes the branch arm growth morphology of dendrites more prominent,and the growth speed also increases;It also promotes the growth of the lateral secondary arm.4)As the operation time step increases,the dendritic growth morphology becomes more obvious,but the growth speed tends to be stable.