单晶镍基合金高温蠕变期间的组织结构及演化

Microstructure and Evolution of A Single Crystal NickelBase Superalloy During High Temperature Creep

通过测定［００１］取向单晶镍基合金的蠕变曲线，结合ＳＥＭ、ＴＥＭ观察表明，合金中组织结构的变化对蠕变抗力有明显影响。蠕变Ⅰ、Ⅱ阶段，蠕变的微观机制是位错的攀移；蠕变第三阶段，位错大量切入筏状γ相中，降低了合金的蠕变抗力，发现交替滑移使筏状γ相扭曲，致使γ／γ两相界面产生空穴或微裂纹，是蠕变断裂的直接原因。

? The microstructure in different creep stages have been observed by means of SEM and TEMThe results showed that the change of microstructure had obvious influence on creep resistance in superalloyThe dislocation climb was the micromechanism of tensile creep in Ⅰ and Ⅱ stagesIn creep ternary stage creep resistance decreased as a result of large number dislocation cutting into γ raftsThe direct reason of creep fracture was cavity and microcrack produced on γ/γ phase interface by the interaction of the multislip