Microstructural Characterization of Yttria-Stabilized Zirconia Sintered at Different Temperatures Using 3D EBSD, 2D EBSD and Stereological Calculations

Piotr Bobrowski,Zbigniew Pędzich,Marek Faryna

doi:10.1007/s11665-017-2794-4

Abstract

A set of yttria-stabilized zirconia samples sintered at increasing temperatures was investigated using two-dimensional (2D) and three-dimensional (3D) electron backscatter diffraction (EBSD) techniques to calculate grain size distributions and grain boundary densities. The obtained results were compared to the results of stereological calculations and revealed that mean intercept length, a commonly used stereological parameter, is ca. 20% lower than an average grain diameter derived from 2D and 3D EBSD data. Moreover, the results based on 2D and 3D EBSD analyses were similar to each other in grain boundary density, while the values obtained from the stereological approach were noticeably lower.

Highlights

Several properties of polycrystalline materials such as strength, toughness, electrical conductivity and diffusivity are influenced by properties of grain boundaries (Ref 1)
We show a comparison of microstructural parameters characterizing the YSZ at four different temperatures obtained from data sets acquired using two experimental approaches (2D and 3DEBSD) which were processed utilizing three different computational methods, namely two-dimensional and three-dimensional image analysis, as well as stereological calculations
It was assumed that grains cut by the edges of the region of interest (ROI) could bias the grain size estimation because their actual size was larger than appeared on the maps

Summary

Introduction

Several properties of polycrystalline materials such as strength, toughness, electrical conductivity and diffusivity are influenced by properties of grain boundaries (Ref 1). Dental and prosthetic applications require a deep knowledge of relationship between and the microstructure and functional properties (Ref 6) Another application of zirconia as solid electrolyte requires microstructure optimization and grain boundary engineering to achieve optimal electrical conductivity (Ref 7, 8). This does not provide all necessary information about the analyzed microstructure (Ref 12) Such an approach allows to determine the grain boundary trace from two-dimensional sections, but the inclination of the boundary plane to the section surface remains unknown. To overcome such a limitation, stereological methods based on probability calculations have been developed to extrapolate two-dimensional experimental results to three-dimensional space (Ref 2). Recent developments in scanning electron microscopy (SEM) enabled a direct three-dimensional (3D) analysis of ceramic microstructure as in the case of serial sectioning experiments in dual-beam SEM, carried out to investigate solid oxide fuel cell electrodes containing zirconia-based composites (Ref 13-15)

Methods

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Discussion

Conclusion