Interface Phenomena Responsible for Bonding between TRIP Steel and Partially Stabilised Zirconia as Revealed by TEM

Abstract

In this study, we demonstrate results of the transmission electron microscopy investigations of phenomena at the interface between partially stabilized zirconia (PSZ) and TRIP steel (steel with the Transformation Induced Plasticity effect). The interface phenomena were studied in thin film samples, which were prepared as a model system by the deposition of PSZ on TRIP steel using magnetron sputtering, and in a bulk composite containing TRIP steel and PSZ powder. The bulk composite was produced by Spark Plasma Sintering. The phase composition and the orientation relationship of several crystallites of PSZ and TRIP steel in the vicinity of their mutual interface were analysed using high resolution transmission electron microscopy (HRTEM). The phase identification was facilitated by using energy dispersive X-ray spectroscopy and electron energy loss spectroscopy (EELS) in scanning transmission electron microscope. In particular, the analysis of the zirconium N2,3 edge in the electron energy loss spectra allowed the cubic, tetragonal and monoclinic ZrO2 phases to be distinguished from each other. Thus mainly EELS complemented the HRTEM analysis of the orientation relationships. The same experimental methods were utilized to follow the local phase transformations near the PSZ/TRIP steel interfaces after a mechanical deformation of the samples.