Al_2O_3/MgAl_2O_4共晶陶瓷定向凝固过程固液界面形貌的研究

Investigation on Solid-liquid Interface Morphology during the Al_2O_3/MgAl_2O_4 Eutectic Ceramics Solidification

采用有限元法计算模拟了Al2O3/MgAl2O4共晶陶瓷区域熔炼定向凝固过程固液界面形貌的演变,研究了熔区坩埚壁面温度、凝固速率对固液界面形貌的影响。结果表明,当熔区坩埚壁面温度从2090℃升至2290℃时,固液界面先由凸界面转为平界面,再转变为凹界面;固液界面前沿的温度梯度随之增大。当凝固速率从1×10-6 m/s升至1×10-5 m/s时,固液界面形貌无明显变化,而熔区长度有所增大。随着凝固过程的进行,熔区长度逐渐增大,凸固液界面的凸出高度逐渐变小。

In order to get the optimized control parameters,the evolution of the solid-liquid interface morphology during the solidification of Al2O3/MgAl2O4 eutectic ceramics with Zone-melting was investigated with numerical simulation.The results showed that as the crucible surface temperature of the melting zone increases from 2090 ℃ to 2290 ℃,the solid-liquid interface changes into a flat interface from a convex one,and then into a concave one,and the temperature gradient in front of the solid-liquid interface increases obviously.As the solidification rate increases from 1×10-6 m/s to 1×10-5 m/s,the melting zone length increases a little,but the solid-liquid interface morphology changes little.The projection of the convex solid-liquid interface becomes smaller,while the melting zone length increases,as the solidification proceeds.