Fe-C合金等温凝固过程枝晶形貌的相场法模拟

Phase-field Simulation of Dendrite Morphologies of Fe-C Alloy in Isothermal Solidification

基于KKS模型,采用相场和溶质场耦合的方法,对Fe-0.5%C(摩尔分数)合金凝固过程枝晶的生长进行了数值模拟,研究了晶粒的长大过程及各向异性强度和扰动等对枝晶形貌的影响。结果表明:晶体生长初期,晶粒形貌为球状,随着时间的推移,晶粒形貌由球状经星形向枝晶形转变,最后形成复杂的树枝晶;随着各向异性的增大,晶粒形貌由球形逐渐向四边形转变,最后形成树枝形;各向异性使晶粒形貌以枝晶方式生长,扰动是引发枝晶的侧向分支的主要原因。

Based on KKS model, the phase-field model coupled with solute-field was used to simulate the microstructural dendrite growth of alloy Fe-0.5%C（mole fraction）. The grain growth process and the influence of anisotropic intensity and noise intensity on dendrite morphologies were investigated. The results show that during the early stages of growth, the morphology of crystal grain is spherical, with the increase of time, the grain morphologies transforms into star shape from spheric shape, and then changes into complex dendrite morphologies, With the increase of anisotropic intensity, the morphology of grain transforms from spheric shape into quadrilateral, and then into dendrite. The morphology of grain becomes dendrite because of the effect of anisotropic intensity. The main reason of dendrite side-branches is caused by the noise intensity.