镍基单晶高温合金的小角度偏离[001]取向对蠕变性能的影响

Influence of small degree deviated from [001] orientation on creep behavior of Ni-based single crystal superalloys---A review

摘要:

小角度偏离[001]取向的镍基单晶高温合金的蠕变性能受温度、γ?尺寸的大小和应力条件的影响。本文综述了镍基单晶高温合金的[001]取向小角度偏离对蠕变性能的影响。不同程度的偏离引起的不同蠕变性能变化,源于不同的蠕变变形机制。不同的蠕变变形机制对应着引起蠕变率发生的不同临界应力。在中温(760℃-850℃),合金的蠕变性能对[001]取向的角度偏离很敏感,即使角度有一点变化也会引起蠕变性能的很大的差异,但是在温度高于850℃以上小角度的取向偏离对蠕变性能影响不大。γ?尺寸的大小对小角度偏离的合金的蠕变性能的影响受温度的制约。在中温,γ?尺寸的大小变化影响着不同的小角度偏离是否引起蠕变性能的变化,但是在高温γ? 相快速伐化,变形机制和γ?尺寸变化无关。

Abstract:

The creep behavior of Ni-based single crystal superalloys small degree deviated from [001] orientation is strongly influenced by temperature, γ? phase size and the level of applied stress. This article presents a review on effects of small orientation deviation on creep behavior of single crystal superalloys. Different creep properties of the alloys with orientation deviation originate from different creep deformation mechanisms. Besides, these mechanisms correspond to different threshold stress which are associated with the occurrence of primary creep and creep rate. At intermediate temperatures, the creep behavior of single crystal alloys is highly sensitive to small misorientation but relatively insensitive above 850 °C. The size of γ? phase is inferred to exert influence on the creep behavior of alloys with orientation deviation at intermediate temperatures. However, at elevated temperatures, the rafting process can be accelerated by higher thermal activation, thus the mechanical properties become less relevant with the size of γ? precipitates coarsening.