Effects of rejuvenation heat treatment on microstructure and creep property of a Ni-based single crystal superalloy

Both surface and internal microstructures of a second-generation Ni-based single crystal (SX) superalloy were studied after creep and rejuvenation heat treatment (RHT). It is indicated that the microstructures, such as the dislocation network, the gamma phase and the gamma' phase, can be recovered to those after the standard heat treatment (SHT). It is found that RHT affected zone (RAZ) formed at the surface is composed of the gamma'-free layer, the transition layer and the recrystallization (RX), which are less than 20 mu m in depth totally. Such depth of the RAZ doesn't affect the properties of the superalloy. The morphology of gamma' phase at the RAZ is related to the composition of the elements. The average creep life after RHT is close to the average life after SHT. It is concluded that RHT could effectively repair SX parts and increase the total life of the sample after a damage by creep. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The study focused on the microstructures of a second-generation Ni-based single crystal superalloy after creep and rejuvenation heat treatment. It was found that the rejuvenation heat treatment had a shallow impact on the microstructures, such as the dislocation network, the gamma phase, and the gamma' phase, without significantly affecting the alloy properties. Additionally, the average creep life after rejuvenation heat treatment was comparable to that after standard heat treatment, indicating that RHT could effectively repair damaged parts and prolong the overall life of the sample.