Effect of interface dislocations on mass flow during high temperature and low stress creep of single crystal Ni-base superalloys
J. He, L. Cao, S. Makineni, B. Gault, G. Eggeler.
Scripta Materialia, Elsevier BV,, 191, 23–28, (2021)
In this work, the nanometer-scale mass flow coupled to dislocation processes near the γ/γ′-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 γ-phase at γ/γ′-interfaces attract γ-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 γ′-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 γ-channels.