【摘要】 从先进镍基单晶高温合金的微观组织稳定性和力学行为2个方面,简要介绍了γ’相筏化、TCP相析出、高温和超高温低应力蠕变以及低周和热机械疲劳的主要研究进展.合金元素Ru的添加提高了合金的高温低应力蠕变寿命,但也间接促进了拓扑倒置现象的发生.随时效时间的延长和时效温度的升高,m相中的难熔元素含量都会明显增加;随着外加应力的增加,m相的析出量增加,压应力则相反.m相在析出的过程中会形成大量的面缺陷,这些缺陷会促进其它TCP相如P相和R相的形核.在高温低应力蠕变的过程中,镍基单晶高温合金中出现另一种重要的a<010>超位错,通过滑移和攀移相结合的方式在γ’相中缓慢运动.在超高温蠕变条件下,开始出现一个蠕变加速的孕育期,这与γ基体在超高温下不同程度的宽化有关.Ru的添加显著降低了合金的层错能,在低周疲劳的过程中可引起层错贯穿γ/γ’界面、a/6<112>Shockley拖后位错切入γ’相等复杂变形机制.在热机械疲劳的过程中,裂纹萌生的位置、微观结构的变化以及抗氧化性能都会影响镍基单晶高温合金的寿命.更多还原

【Abstract】 Ni-based single crystal superalloys have been widely used to produce turbine blades for advanced aero-engines because of the super temperature-related microstructural stability and comprehensive mechanical properties. However, due to effects of the high temperature and complicated stresses in service, the microstructures of superalloys might gradually evolve and fail in different modes. The present paper reviews the progress of microstructural stability and mechanical behavior including the γ’ phase rafting, TCP phase precipitation, high temperature creep, low cycle fatigue and thermomechanical fatigue of single crystal superalloys. The addition of Ru improves the creep life of superalloys, but also indirectly promotes the occurrence of"topological inversion". On the other hand, with the increase of aging temperature and time, the contents of refractory elements in m phase rise significantly. With the increase of applied tension stress, more m phase precipitate from the g matrix, whereas inverse tendency is shown under compression stress. Numerous planar defects are formed during precipitation of m phase,and these defects promote the nucleation of P and R phases. During high temperature and low stress creep, an important dislocation a<010> superdislocation is observed, which moves in the γ’ phase slowly by a combination of slide and climb. Under very high temperature, incubation with accelerating creep rate occurs before the primary stage, which relates to the extending process of the g width. At last, the stacking fault energy is significantly reduced after Ru additions, and thus a series of complex deformation mechanisms occur during low cycle fatigue,e.g. stacking faults penetrating g /γ’ interface, trailing a/6<112> Shockley dislocations shearing into the γ’ phase.During thermomechanical fatigue, the life of superalloys is influenced by the site of crack initiation, microstructural evolution and oxidation resistance.更多还原