How do the grains slide in fine-grained zirconia polycrystals at high temperature?

TL;DR

This study investigates how grains slide in fine-grained zirconia polycrystals at high temperatures, revealing the presence of amorphous intergranular phases that influence their mechanical behavior.

Contribution

The paper combines mechanical spectroscopy and TEM to demonstrate the existence of amorphous grain boundary phases in zirconia at high temperatures, clarifying their role in grain sliding.

Findings

Evidence of intergranular amorphous phases at high temperature

Intergranular amorphous phases observed at room temperature after quenching

Implications for understanding zirconia's mechanical degradation

Abstract

Degradation of mechanical properties of zirconia polycrystals is hardly discussed in terms of solution-precipitation grain-boundary sliding due to experimental controversies over imaging of intergranular amorphous phases at high and room temperatures. Here, the authors applied the techniques of mechanical spectroscopy and transmission electron microscopy (TEM) to shed light on the amorphization of grain interfaces at high temperature where the interface-reaction determines the behaviour of fine-grained zirconia polycrystals. They present mechanical spectroscopy results, which yield evidences of an intergranular amorphous phase in silica doped and high-purity zirconia at high temperature. Quenching of zirconia polycrystals reveals an intergranular amorphous phase on TEM images at room temperature.