Phase transformation in Ce-Doped zirconia single and oligo-crystals: In-situ micro-compression with electron back-scattered diffraction analysis

This study examines for the first time phase transformation of single and oligo-crystalline tetragonal zirconia micropillars under in-situ compression with Electron Back-Scattered Diffraction (EBSD). The tetragonal-to-monoclinic (t-m) phase transformation in ceria-doped zirconia pillars is initiated when a critical stress threshold is reached and propagates along individual grains with increasing stress. Grain boundaries, triple junctions, and small processing-related pores, which lead to localized stress concentrations, facilitate the transformation by lowering the effective applied critical stress. Our findings also align well with the predictions of the crystallographic theory and extend observations from prior studies on single-crystal systems, thereby providing a clearer understanding of the sequences of stress-induced phase transformation in oligo-crystalline tetragonal zirconia.