Influence Of Interface Kinetics Parameters On The Overall Fluctuation Instability Of The Interface Morphology Of Deep Cell Crystal

During directional solidification,different physical parameters can affect the growth and stability of the interface.In this paper,the influence of interfacial dynamics on the morphological stability of deep cellular crystals during directional solidification is studied.By establishing a deep cellular crystal growth model,using the multivariable method and the matching asymptotic method,the steady ground state solution and the multivariable asymptotic expansion solution of the external region perturbation dynamics are obtained,and the dispersion formula is obtained.Then,the root solution is obtained,the dispersion formula of the singularly perturbed system and the internal solution near the singular point are obtained,and the quantization conditions for the interface morphology are obtained by matching the internal solution with the external solution.The basis forjudging the stability of the system is obtained,and the stability of the growth of deep cellular crystals is analyzed.The results show that there are two global instability mechanisms in the directional solidification system with deep cell crystal growth considering the interface dynamic parameters:the global oscillation instability mechanism caused by the complex eigenvalue spectrum and the low frequency instability mechanism caused by the real eigenvalue spectrum.The results show that the directional solidification system with deep cell growth considering the interface dynamic parameters has an overall oscillation instability mechanism caused by the complex eigenvalue spectrum.Stability analysis shows that in the overall oscillation instability mechanism.the interface stability parameter ε is related to the cell relative parameter λ0.In the low-order approximation,the smaller the pure melt temperature TM,the greater casting speed V,the greater temperature gradient GT,the greater the far-field impurity concentration C∞,the more unstable the system,these physical parameters will affect the interface stability.When other physical parameters are fixed,the larger the interface dynamic parameter M*,the larger the stable region of the overall fluctuation instability of the dendritic structure with strong oscillation of the neutral mode,and the more stable the system is.The interface dynamic parameters stabilize the system.