A wide range of alloys, ceramics and geological materials are either: (i) metastable and accommodate the imposed thermal or mechanical stimuli by transforming from their parent phase to different daughter/product phase(s) via a shear-type mechanism, (ii) are polymorphic and exist as more than one crystal structure at the same time, or (iii) contain intermetallic complexes that precipitate out of the solid solution matrix. In point (i), materials undergoing irreversible and reversible phase transformation exhibit the transformation-induced plasticity (TRIP) and shape memory (SM) effects, respectively.
Regardless of their classification as TRIP, SM, polymorphic or precipitate-matrix systems, parent -daughter phases share a distinct crystallographic orientation relationship (OR) with each other. An OR is defined using transmission electron microscopy (TEM) terminology as near parallel relations between specific, rational planes and directions between parent-daughter phases on either side of an interphase boundary segment.
Knowledge of the OR provides insight into the deformation and thermodynamic behaviour of parent-daughter phases; which in turn, enables the development of newer materials that better exploit these phenomena or improves on our understanding of geological phenomena.
ORs between parent-daughter phases are conventionally found via double-tilt experiments involving selected area electron diffraction (SAED) in a TEM. The drawbacks include: (i) the analysis being spatially limited to a few tens of µm2, (ii) the laborious manual collection of SAED patterns, (iii) the probability of only indexing the dominant OR, and (iv) beam time limitations.
Alternatively, electron back-scattering diffraction (EBSD) can be applied to characterise the ORs in a statistically significant manner by interrogating thousands of parent-daughter interphase boundary segments over large areas of interest. Thus, the focus of this talk is to: (i) showcase unique software tools that automatically find and catalogue the ORs between parent-daughter interphase boundaries in exemplar EBSD maps and, (ii) validate the ORs via conventional SAED.