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利用多相场模型模拟了共晶合金CBr4-C2Cl6定向凝固变速生长过程,研究了阶跃变速、线性变速以及震荡变速三种变速条件下共晶片层间距的调整以及形态的变化.结果表明:在变速生长过程中,界面平均生长速率与平均过冷度随抽拉速率的变化均产生滞后效应;阶跃增速时,片层间距的调整通过突变分岔形式进行,而阶跃减速时,通过片层的逐步湮没与合并以及自身相的长大方式进行,两个过程表现出强烈的非对称性;线性增速过程,片层间距的调整通过逐步分岔进行,而线性减速过程,片层间距的调整机理与阶跃减速过程类似.线性增速与线性减速过程片层间距的调整具有逆对称性;在震荡变速作用下,片层生长形成类似1λO振荡不稳定性形态.
The multi-phase field model was used to simulate the variable-speed growth process of eutectic alloy CBr4-C2Cl6 by directional solidification, and the adjustment of eutectic layer spacing and the change of morphology under three variable speed conditions of step speed change, linear speed change and oscillatory speed change were studied. In the process of variable speed growth, the average growth rate and the average undercooling of the interface all produce a hysteresis effect with the change of the drawing rate. In the case of step growth, the adjustment of the layer spacing is carried out by the mutation bifurcation, and when the step slows down, The gradual annihilation and integration of the lamellae and the growth of their own phase, the two processes showed a strong asymmetry; linear growth process, the adjustment of lamellar spacing through gradual bifurcation, and linear deceleration process, lamellar The adjustment mechanism of pitch is similar to that of step deceleration, and the adjustment of layer spacing during linear growth and linear deceleration is inversely symmetrical. Under the action of oscillatory speed change, the lamellar growth is similar to 1λO oscillatory instability.