共晶变速生长的多相场模拟

利用多相场模型,模拟了CBr4-C2Cl6共晶合金定向凝固稳态生长及非稳态变速生长过程.稳态生长模拟结果与Jackson-Hunt共晶理论描述一致,验证了模型的可靠性.非稳态变速生长模拟表明:阶跃增速或减速时,片层间距的调整分别通过突变分叉、或逐步湮没与合并以及自身相的长大方式进行,两者片层间距的选择过程表现为强烈的非对称性;相对于阶跃时刻,片层间距调整、界面平均生长速率与平均过冷度的变化均具有滞后性.

Multiphase field modeling the eutectic growth under varying velocity

By multiphase field model,the stable and non-stable growths of eutectic CBr_4-C_2Cl_6 alloy are simulated.The simulated results of stable growth are accordant with Jackson-Hunt's eutec- tic theory,which proved that the model is reliable.For the non-stable growth under varying growth velocity,the results show that during step increase or step decrease in velocity,the mechanism of the lamellar spacing adjustment is through abrupt lamellar branching or progressive merging and anni- hilation accompanied the growing up by itself,respectively,moreover,there exists strong asymmetry between these two processes during lamellar adjustment.At the moment of step changing in velocity, the adjustment of lamellar spacing,the changes of average velocity and average interface undercooling have all the hysteresis effect.