Correlation between yttrium segregation at the grain boundaries and the threshold stress for plasticity in yttria-stabilized tetragonal zirconia polycrystals

Nowadays, the high-temperature plasticity of yttria-stabilized tetragonal zirconia polycrystals (YTZPs) is successfully explained in terms of a threshold stress. Despite the fact that its existence is very well proved experimentally, the origin and nature of the threshold stress are still unexplained. This work develops a possible explanation for the threshold stress in YTZPs. The model developed in this paper is able to explain quantitatively the dependence of this threshold stress with temperature and grain size. The model is able to predict the influence of a glassy phase present at grain boundaries and the values of the threshold stress in YTZP nanocrystals. The theoretical results are discussed and compared with the available data in the literature.