Effects of crystal orientations on the cyclic deformation behavior in the low cycle fatigue of a single crystal nickel-base superalloy
Effects of crystal orientations on the cyclic deformation behavior in the low cycle fatigue of a single crystal nickel-base superalloy
复制标题
DOI：
10.1016/j.matdes.2017.06.047
复制
发表时间：
2017-10
影响因子：
8.4
通讯作者：
Liu Liu-Liu;J. Meng;Jinlai Liu;T. Jin;Xudong Sun;Hai-feng Zhang
中科院分区：
文献类型：
--
作者：
Liu Liu-Liu;J. Meng;Jinlai Liu;T. Jin;Xudong Sun;Hai-feng Zhang
研究了[001]、[011]和[111]取向的含Re镍基单晶高温合金在980 °C低周疲劳过程中的循环应力响应，并对相应的变形组织进行了观察，建立了清晰的组织-力学关系。结果表明，[001]试样在应变幅增大时，变形早期表现为循环软化，而[011]和[111]试样在大应变幅下表现为循环软化，在小应变幅下表现为循环硬化。软化响应主要与位错网络的形成、γ′的退化和位错回复过程有关。此外，[011]试样中大量平行排列的位错减少了不同滑移系之间位错相互作用的可能性，导致循环硬化。对于[111]试样，由于γ通道中有大量位错堆积，位错运动阻力增大，导致循环硬化。研究结果揭示了不同取向合金循环应力响应行为的微观变形机制。
Cyclic stress responses during low cycle fatigue of a Re-bearing Ni-base single crystal superalloy with [001], [011] and [111] orientations have been investigated at 980 °C, and attention is paid to the corresponding deformation microstructure to establish a clear microstructure-mechanical relationship. It is found that deformation of the [001] specimens with increased strain amplitude is characterized by cyclic softening at the early stage, while the [011] and [111] specimens exhibit cyclic softening under large strain amplitude and cyclic hardening under small cyclic amplitude. The softening response is related chiefly to the formation of dislocation networks, γ′ degradation and the dislocation recovery process. Moreover, plenty of parallel aligned dislocations in the [011] specimens reduce the probability of dislocation interactions among different slip systems, resulting in cyclic hardening. With respect to the [111] specimens, since a considerable number of dislocations pile up in γ channels, the resistance of the dislocation movement increases and cyclic hardening is resulted. Our results throw light upon microscopic deformation mechanism responsible for the cyclic stress response behaviors of the alloy with various orientations.