Role of grain constraint on the martensitic transformation in ceria‐doped zirconia

Zirconia polycrystals have historically suffered from catastrophic cracking during the tetragonal‐monoclinic martensitic transformation. Recently, transformation‐induced cracking has been avoided by doping to achieve crystallographic compatibility between the transforming phases. However, these mate...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2021-02, Vol.104 (2), p.1156-1168
Main Authors: Pang, Edward L., Olson, Gregory B., Schuh, Christopher A.
Format: Article
Language:English
Subjects:
Autocatalysis
Cerium oxides
Comparative studies
Composition
Compressive properties
Crystallography
Exhaustion
Force distribution
fracture
martensitic transformation
Martensitic transformations
Nucleation
Pellets
Polycrystals
shape‐memory ceramic
Sintering (powder metallurgy)
Stress concentration
Thermodynamic models
thermodynamics
Transformation temperature
zirconia
Zirconium dioxide
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Summary:Zirconia polycrystals have historically suffered from catastrophic cracking during the tetragonal‐monoclinic martensitic transformation. Recently, transformation‐induced cracking has been avoided by doping to achieve crystallographic compatibility between the transforming phases. However, these materials showed depressed transformation temperatures and incomplete transformation, the causes for which are yet unknown. In this work, we probe these phenomena by performing a comparative study of sintered pellets and powders. We characterize the thermally induced transformation in a series of ZrO2‐CeO2 compositions by in situ diffraction and calorimetry and develop a thermodynamic model of the system. In compositions exhibiting reduced cracking, we find that transformation temperatures are depressed in pellets but not in powders. Correspondingly, we measure significant compressive strains in pellets consistent with thermodynamically expected transformation temperature depression, demonstrating the influence of grain constraint and the resultant pressure build‐up. However, we find that both pellets and powders exhibit incomplete transformation. In pellets, this is attributed to early exhaustion of autocatalysis caused by grain constraint, whereas in powders, this is attributed to insufficient driving force for distributed heterogeneous nucleation.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.17526