Initial microstructural study of a Ce–La alloy using electron backscattered diffraction

To better understand and exploit the unique electronic and structural properties of f-block metals and their alloys it is perceived that an improved knowledge of the microstructural characteristics and phase changes as a function of temperature and pressure, is necessary. For other different types of metallic systems, the use of electron back-scattered diffraction (EBSD) is becoming a common practice in order to obtain detailed microstructural information, but this has, as yet, been very limited in case of f-block metals. Because of their extreme affinity to oxygen and rapid surface reaction, EBSD studies of this metal-category are very sparse with only one work published on cerium metal providing an example of technical hurdles for a prerequisite oxide-free metal surface. Specifically the need to remove the oxide by ion etching was considered essential to enable a successful EBSD analysis. The current work presents the results of a first attempt to characterise the microstructure of a Ce–La alloy using EBSD. It demonstrates that high quality diffraction patterns and crystal orientation maps can be successfully obtained following a carefully controlled preparation of the alloy surface in the open laboratory by applying a simple and reproducible electro-polishing procedure without a further need for ion etching in vaccuo.

Research highlights
► First ever successful EBSD microstructural analysis of Ce–La alloy.
► Successful preparation using electro-polishing in the open laboratory.
► Equiaxed grains 20–40 μm in size dominate the microstructure, with random orientations, relatively straight grain boundary contacts and no evidence for crystal twinning.
► All grains matched to a fcc γ-phase.
► Problematic presence of entrapped oxide particles.