Yielding Behavior Of A Single-Crystalline Gamma'-Strengthened Co-Ti-Cr Superalloy

The anomalous yielding behavior known from Ni3Al or Ni-base superalloys is explained by the formation of immobile dislocation configurations via cross-slip of the leading superpartial of anti-phase boundary-coupled dislocation pairs. A systematic investigation of the anomalous yielding behavior of a single-crystalline Co-11Ti-15Cr superalloy by transmission electron microscopy revealed the absence of similar sessile dislocation configurations during the initial yielding stage. Shearing of gamma' precipitates via super-lattice stacking fault formation is the dominant deformation mechanism at the peak temperature. Furthermore, the high density of superlattice stacking faults and their interactions also lead to a pronounced work-hardening anomaly. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc.