晶体取向对单晶高温合金一次枝晶间距的影响

在固液界面微单元热量平衡分析的基础上，建立了晶体取向对一次枝晶间距影响的理论模型。该模型表明，一维择优晶体取向与宏观定向凝固方向偏离越远，一次枝晶间距越小，对ＤＤ８单晶高温合金凝固组织尺度的实验研究结果表明，晶体取向对一次枝晶间距的影响趋势和理论模型相吻合，其影响程度和固液界面温度梯度及定向凝固速率有关。模型及实验都表明，提高固液界面温度梯度和定向凝固速率，晶体取向对一次枝晶间距的影响程度减弱。

INFLUENCE OF CRYSTAL ORIENTATION ON THE PRIMARY DENDRITE ARM SPACING OF A SINGLE CRYSTAL SUPERALLOY

A model for relating the primary dendrite arm spacing to the crystalorientation has been developed.An experiment for investigating the primary dendrite arm spacing in single crystal superalloy DD8 has also been carried out.The results indicate that the primary dendrite arm spacing decreases when the preferred orientation of the dendrite deviates from the solidified direction.The influence of the crystal orientation on the primary dendrite arm spacing is much slight with higher thermal gradient and higher solidification rate.The experimental results are consistent with the prediction of the model.