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Eutectoid Decomposition of MgO‐Partially‐Stabilized ZrO 2
Author(s) -
FARMER SERENE C.,
HEUER ARTHUR H.,
HANNINK R. H. J.
Publication year - 1987
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.1151-2916.1987.tb05664.x
Subject(s) - eutectic system , nucleation , materials science , decomposition , annealing (glass) , tetragonal crystal system , monoclinic crystal system , transmission electron microscopy , alloy , crystallography , scanning electron microscope , analytical chemistry (journal) , phase (matter) , mineralogy , chemical engineering , metallurgy , chemistry , crystal structure , composite material , nanotechnology , organic chemistry , chromatography , engineering
Euctectoid decomposition of cubic ( c ) ZrO 2 in MgO‐partially‐stabilized ZrO 2 (Mg‐PSZ) has been studied using optical, scanning electron, and transmission electron microscopy. Alloys containing from 8.1 to 18.6 mol% MgO were decomposed by annealing between 1100° and 1300°C for times up to 16 h. The eutectoid products nucleated heterogeneously at the grain boundaries and advanced into the adjoining two‐phase grains. Decomposition proceeded as a “cellular” reaction involving the cooperative growth of MgO and a low‐solute ZrO 2 phase with either monoclinic ( m ) or tetragonal ( t ) symmetry. The MgO morphology is rodlike and exhibits a well‐defined orientation relationship to m ‐ZrO 2 . The rate of eutectoid decomposition was a maximum at 1200°C and was greater in the solute‐rich materials at all temperatures. At 1100°C, SrO doping decreased the nucleation rate of the eutectoid product in a 9.7 mol% alloy, thus strongly suppressing the decomposition rates; at the higher decomposition temperatures, the SrO was less effective.