摘要
采用耦合扰动的相场模型,对枝晶生长过程进行模拟,研究了热扰动强度对枝晶形貌的影响以及热扰动和相场扰动对枝晶侧向分枝形成的影响。结果表明,随着热扰动幅值的减小,枝晶尖端分叉程度减小,横向的二次枝晶变得发达,纵向的二次枝晶退化,doublon结构消失,形成了高度对称的枝晶结构;热扰动能够引发枝晶的侧向不稳定,是侧向分枝形成的主要原因,相场扰动对侧向分枝的贡献不大,在计算中一般可以忽略;当Fu取值适当时,热噪声的引入能引发侧向分枝,但不改变枝晶尖端的稳态行为。
The evolution of the dendrite growth was simulated utilizing the phase-field model with coupled fluctuation, and the effect of thermal fluctuation intensity on the dendrite morphology and the influence of thermal fluctuation and phase-field fluctuation on the formation of dendrite side-branches were investigated, that the results show that with decrease in the thermal fluctuation amplitude,the divarication degree of the dendrite tip decreases, and the lateral secondary dendrites become strong, the longitudinal secondary dendrite degenerate, doubloon structure disappears, thus forms the extremely symmetrical dendrite structure. Thermal fluctuation can trigger the side instability of dendrite, which is the main reason of forming side-branches~ phase-field fluctuations have little contribution to the side-branches, it can usually be neglected in the calculation; when an appropriate value of Fu is chosen, the introduction of thermal noise can induce side-branches, but it does not change the steady behavior of the dendrite tip.
出处
《铸造技术》
CAS
北大核心
2008年第6期777-781,共5页
Foundry Technology
基金
中北大学校基金项目200712
关键词
扰动
枝晶
相场
二次分支
Fluctuation
Dendrite
Phase-Field
Side-Branches
