Creep anisotropy of a 3rd generation nickel-base single crystal superalloy at 850 °C

The influence of orientation on the creep behaviors of a 3rd generation single crystal superalloy was studied at 850 degrees C. It is found that the creep properties are highly anisotropic for [001], [011] and [111] specimens. The [111] samples show the longest creep life. The [011] specimens display the shortest creep life of less than 1 h and the longest elongation. And [001] specimens exhibit the intermediate creep life. Electron backscattered diffraction (EBSD) analyses and transmission electron microscopy (TEM) observations show that the creep anisotropy is mainly related to the slip systems that activated, especially the < 112 > {111} slip systems. Single slip of < 112 > {111} system results in a high creep strain and poor property, which controls the primary creep of [001] and entire creep stage of [011] specimens. While interaction of primary and secondary < 112 > {111} systems has an effect on work hardening, which occurs during steady and tertiary creep of [111] orientation and hence results in the best creep property of [111] specimens. By comparing with SRR99 and CMSX-4 alloys, higher Re content in DD33 alloy may facilitate the formation of continuous stacking faults in [011] specimens and activation of multiple < 112 > {111} slip systems in [111] specimens, which will affect the creep property and anisotropy.