【摘要】 利用溶质扩散控制模型对TiAl合金柱状晶/等轴晶转变过程进行了数值模拟,结果表明,等轴晶在柱状晶前沿形核及生长过程中,当两个扩散场相遇时,观察到成分冲击波,它可能是导致柱状晶停止生长的一个主要原因.利用该模型,对小铸件柱状晶/等轴晶转变过程进行了预测,在模拟过程中发现柱状晶界面前沿液相温度梯度,成分过冷度可联合对柱状晶/等轴晶转变产生影响,模拟与实验观察符合较好.更多还原

【Abstract】 Solute diffusion controlled solidification model was employed to simulate the columnar to equiaxial transition (CET) of TiAl alloy casting. The simulation results show that solute shock wave occurs when the diffusion fields of columnar and equiaxial dendrites meet. It could be one of the main factors blocking the columnar dendrite growth. Using this model, the CET in small castings was qualitatively predicted. It was found that the thermal gradient and solute undercooling ahead of the columnar tips of CET act jointly on CET, being in good agreement with experimental observations.更多还原