| Abstract |
| The effects of growth of the Υ` and η phase on the LCF in Nb-A286 superalloy are investigated by fatigues test, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The change of precipitates morphology, amount of phase and control of size are also discussed. Under the continuous low cycle fatigue, fatigue life is increased with increasing Υ` size and amount of ηphase. In the investigation of a fracture surface after low cycle fatigue test, fracture mode is changed from intergranular fracture mode to transgranular fracture mode with increasing Υ` size and amount of η phase. It is changed from planar slip to bowing dislocation with increasing Υ` size. Slip induced cavitation by local stress concentration due to planar slip impinged on the grain boundary is retarded by a larger precipitation than that of unaged sample. Therefore, fatigue life is increased with Υ` size and amount of η phase. These results will by applied to the development of a new alloy for the improvement of fatigue life. |
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| Key Words |
| High temperature low cycle fatigue, γ`, h phase, Intergranular fracture, Nb-A286 superalloy |
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