二元合金非等温凝固枝晶生长相场法模拟

Numerical Simulation of Dendritic Growth of Binary Alloy During Non-isothermal Solidification

基于KR模型,耦合温度场、溶质场与相场,对二元合金非等温凝固枝晶生长过程进行模拟,分析热质扩散比Lewis(刘易斯数)对枝晶生长、温度场及溶质场分布的影响。分析模拟结果表明;Lewis数低时,枝晶生长慢,热扩散比溶质浓度扩散慢,导致热量和溶质扩散层厚度变小,界面处温度梯度和溶质浓度梯度幅值减小;相反,Lewis数高时,枝晶生长快,热扩散比溶质浓度扩散快,导致热量和溶质扩散层厚度变大,界面处温度梯度和溶质浓度梯度幅值增大。

The phase-field model based on KR model in which temperature-field is coupled with solute-field was used to simulate dendrite growth of binary alloy during non-isothermal solidification.The influence of Lewis number（Lewis） on dendrite growth,the temperature field and solute distribution was analyzed.The results show that,under the lower Lewis number,the dendritic growth is slowly,thermal diffusion is slower than solute diffusion,resulting in the thickness of heat and solute diffusion layer decreasing,the amplitude of interface temperature gradient and concentration gradient of the solute decreases.Under the higher Lewis number,the dendrite grows fast,thermal diffusion is faster than solute diffusion,resulting in the thickness of heat and solute diffusion layer increasing,the amplitude of interface temperature gradient and concentration gradient of the solute increases.