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一、前言高温合金定向凝固是近代航空发动机叶片采用的先进技术,柱状晶按[001]择优取向,消除了与主应力轴垂直的横向晶界,从而提高了合金[001]方向的蠕变强度、塑性、抗热疲劳等综合性能,大幅度地延长零件的使用寿命。由于各向异性,定向材料的横向以及纵向晶界上的横向分段和枝晶间仍是裂纹起源和扩展的薄弱区域。添加合金元素 Hf 可以提高普通铸造高温合金的中温性能已有许多报道,Hf 对改善定向凝
I. INTRODUCTION Directional solidification of superalloy is an advanced technique adopted by modern aviation engine blades. The preferential orientation of columnar crystals by [001] eliminates the transverse grain boundaries perpendicular to the principal stress axis, thereby increasing the creep strength in the [001] direction of the alloy , Plastic, thermal fatigue and other comprehensive performance, significantly extend the service life of parts. Due to the anisotropy, the lateral segments and dendrites in the transverse and longitudinal grain boundaries of the oriented material are still the weak areas where cracks originate and expand. Addition of alloying elements Hf can improve the mid-temperature performance of ordinary foundry superalloy There have been many reports, Hf to improve the directional condensation