Effect of interface dislocations on mass flow during high temperature and low stress creep of single crystal Ni-base superalloys

In this work, the nanometer-scale mass flow coupled to dislocation processes near the gamma/gamma'-interface during high temperature and low stress creep of a model Ni-base single crystal superalloy is investigated. In the early creep stages, the dislocation networks in the gamma-phase at gamma/gamma'-interfaces attract gamma-stabilizing elements like Cr, Co and in particular Re, resulting in compositional gradients close to the interface. At larger strains, where dislocations frequently cut into the gamma'-phase, this local interfacial enrichment in these elements is no longer observed. The cutting dislocations take part of the segregated atoms away, whilst the remaining atoms are released and diffuse back into the gamma-channels. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

During high temperature and low stress creep, nanometer-scale mass flow coupled to dislocation processes near the gamma/gamma'-interface was investigated in a model Ni-base single crystal superalloy. In the early creep stages, compositional gradients close to the interface were observed as dislocation networks attracted gamma-stabilizing elements. However, at larger strains where dislocations cut into the gamma'-phase, the local interfacial enrichment in these elements was no longer observed. The cutting dislocations took segregated atoms away, while the remaining atoms were released and diffused back into the gamma-channels.