High-Resolution Characterization of Inclined Stacking Faults and Their Bounding Partial Dislocations in fcc and L12 Crystals

Abstract Stacking-fault-based deformation mechanisms are a frequent feature of deformation processes especially in γ / γ ′-strengthened superalloys and low stacking fault energy alloys. Uncovering the microscopic mechanisms responsible for their formation through transmission electron microscopy has been a topic of interest for decades. However, high-resolution analysis has so far been limited to the [110] zone axis and edge-on glide planes, precluding the investigation of [001]-oriented specimens. Here, we demonstrate that the capabilities of high-resolution fault analysis can be expanded to inclined glide planes in both the [110] and [001] zone axes. We show that not only the type of a given stacking fault but also the dislocation configuration responsible for its formation can be comprehensively assessed even for an inclined fault geometry. From a single [110] micrograph of the CoNi-base superalloy ERBOCo-4 deformed under constant strain-rate compression at 850 °C, the leading end of an extrinsic fault on an inclined glide plane inside a γ ′ precipitate is directly revealed to consist of two identical Shockley partials on neighboring planes according to the Kolbe mechanism. The introduction of this analysis method for faults in the fcc and L1 2 structures may facilitate future investigations of planar-fault-based deformation mechanisms in superalloys and other material systems.