Number Simulation And Key Technologies Study Of NiCu Alloy By Phase-field Method

In the process of materials solidification, the microstructure formation and evolutionhas an important influence on the material using performance. The numerical simulation ofmicrostructure solidification contributes to a better understanding in the properties ofmaterials microstructure and optimizing the metal casting processing technology. Thephase-field method uses the diffusion interface model, it has been paid more and moreattention in the numerical simulation of solidification microstructure formation processbecause it has no need to trapping the solid-liquid interface.In this paper, we used the Phase-field model to simulate the dendrite growth of pure Nimetal in two-dimensional, three-dimensional and the directional solidification, then by meansof coupling the temperature field and solute field with the PF model to simulate the NiCualloy dendrite growth process in the non-isothermal conditions. We discuss the dendritemorphology evolution in the phase field and the distribution of temperature field and solutefield. The effects of dendrite growth with different interface kinetics parameters has beendiscussed.The parameters of the interface atomic motion characterized the atoms adding speedfrom the liquid to the solid-liquid interface, when the parameters is small, the speed is fast, thepushing velocity from the solid-liquid interface to the liquid increasing, Then the solid-liquidinterface frontier become instability, and the disturbance can be easily amplification, thedendrite growth velocity is increasing and the side branches appeared. With the increasing ofthe parameter, the disturbance is inhibited, the dendrite growth velocity is decreasing with themorphology of dendrite appear smooth. The results obtained in this simulation are consistentwith the results of MSC to verify the accuracy of the simulation.The interface thickness can not only affect the authenticity of the dendrite simulation, butalso the accuracy of the numerical calculation. When the interface thickness is lager, errornoise can be easily introduced which can lead to the disturbances amplification, the tipvelocity become faster and the dendrite morphology is bulky with lateral branch. With the decrease of interface thickness, the error noise can be restrained and the dendrite shows asmooth morphology, the tip velocity tend to reduced as well. The error noise can affect theresults strongly that should be controlled in the simulation.When the thermal diffusion ratio of solid-liquid interface is small, the thermal diffusivityof solid is relatively low, the tip velocity of the dendrite growth is faster and the latent heatpile up on the middle and lower segments of dendrite which can produce a heat disturbanceand the lateral branch has been induced. With the thermal diffusion ratio of solid-liquidinterface get higher, the thermal diffusivity of solid became bigger as well. The latent heat canbe transferred quickly to the top of dendrite, the tip velocity of the dendrite growth reducedand the heat disturbance is restrained that a smooth morphology formed finally.The interface anisotropy determines the grain growth in the form of dendrite, As theinterface anisotropy increases, the growth of tip velocity increases. The disturbance can beeasily magnified, and a complicated grain morphology was formed. When the interfaceanisotropy is small, the disturbance is restrained and the growth velocity of dendrite becomelower.