Interplay between Habit Plane and Orientation Relationship in an Electron Backscatter Diffraction Analysis: Using the Example of η′-Al8Fe3 in η-Al5Fe2

Abstract

The Al5Fe2 intermetallic rouses interest due to its rapid formation at the interface between iron/steel and aluminum by reactive interdiffusion. Only in the last few years have the differently ordered states of that intermetallic been elucidated (η′, η″, η‴ and ηm). In the present work, the microstructural characteristics of the plate-shaped η′-Al8Fe3 phase regions in a η‴/η-phase matrix were investigated, determining the habit planes from two-dimensional electron backscatter diffraction (EBSD) maps. Within an η grain, there are altogether four variants of η′ with four characteristically crystallographic equivalent habit planes with respect to η. These habit planes have been determined based on their traces measured for differently oriented η containing the η′ plates, applying different methods. One method in particular makes use of the connection between orientation relationship and habit planes. Using these methods, the habit planes were determined as {hkl}η and {hkl}η′, both with {1 1.8 2.5}η/η′. Thus, essential characteristics of the microstructure are provided for further analysis of the phase transformation of the η phase to the η′-Al8Fe3 phase.