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Phase Transformation in Y 2 O 3 ‐Partially‐Stabilized ZrO 2 Polycrystals of Various Grain Sizes during Low‐Temperature Aging in Water
Author(s) -
Li JingFeng,
Watanabe Ryuzo
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02677.x
Subject(s) - materials science , grain size , tetragonal crystal system , nucleation , sintering , yttrium , atmospheric temperature range , phase (matter) , grain boundary , monoclinic crystal system , mineralogy , crystallography , metallurgy , microstructure , thermodynamics , chemistry , crystal structure , oxide , physics , organic chemistry
ZrO 2 ‐2 mol% Y 2 O 3 crystals with average grain sizes from 0.51 to 0.96 µm were prepared by sintering in air at 1400°C for 2 to 100 h. The tetragonal‐to‐monoclinic phase transformation associated with the low‐temperature degradation was investigated to clarify how the presence of water directly affects the influence of grain size on transformation. The specimens were exposed to water at 80–120°C, a temperature range in which transformation by thermal activation is difficult in the absence of water. Contrary to expectations, this type of low‐temperature transformation did not accelerate monotonously with increasing grain size. Instead, the amount of phase transformation first decreased, reaching a constant value, and then increased with increasing grain size. Such interesting results can be explained satisfactorily by the combined influences of grain size on the nucleation process, because of preferential dissolution of yttrium at the grain boundaries, and the intrinsic transformability of Y 2 O 3 ‐doped tetragonal ZrO 2 grains.