The existence of confined states (or complexions) in interfaces has been investigated since at least two decades, especially in grain boundaries by HRSTEM as an attempt to explain phenomena like abnormal grain growth, grain boundary embrittlement and activated sintering, that haven’t been successfully described by purely mechanistic explanations. Recently, correlative APT&TEM investigations in a Fe9wt.%Mn BCC alloy with dislocations enriched with Mn have suggested that the strain field of dislocations can induce state transitions that resembles complexion transitions. In this study, supported by a thermodynamic model, it was reported that a FCC-like structure can be stabilized in the confined area of the dilatation zone of edge dislocations in a BCC matrix. This talk concentrates in how correlative APT&TEM are being used for the characterization of linear and planar complexions in model Fe-Mn alloys.
The first part of this talk focuses on how APT by itself can be used as a powerful tool to estimate the composition in dislocations decorated by Mn and how this compositional profiles can be used to estimate the size of the transformed regions. At the same time, the main possible artifacts in APT data will be discussed and the routine to reconstruct APT data and characterize edge dislocations using the dataset crystallography will be addressed.
The second part of this talk relates to APT&TEM correlative analysis, especially the role of TEM to give support to APT analysis. In this context, selected area diffraction pattern (SADP) experiments were accomplished in order to verify the hypothesis of local change of the crystallographic structure and Burgers vector analysis to verify the dislocation character.