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Discontinuous Dissolution and Grain‐Boundary Migration in Al 2 O 3 ‐Fe 2 O 3 by Oxygen Partial Pressure Change
Author(s) -
Lee HoYong,
Rhee YoungWoo,
Kang SukJoong L.
Publication year - 1996
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.1151-2916.1996.tb08778.x
Subject(s) - corundum , spinel , grain boundary , dissolution , mineralogy , precipitation , materials science , oxide , partial pressure , microstructure , oxygen , phase (matter) , analytical chemistry (journal) , metallurgy , chemistry , organic chemistry , meteorology , chromatography , physics
When sintered 95Al 2 O 3 ‐5Fe 2 O 3 (wt%) specimens constituting corundum grains and iron aluminate spinel precipitates were annealed under high oxygen partial pressure (P o 2 ) where only a corundum phase is stable, fast dissolution of particulate spinel precipitates occurred, together with the migration of corundum grain boundaries. Behind the migrating boundaries, a corundum solid solution enriched with Fe 2 O 3 formed. Discontinuous dissolution (DD) of particulate spinel precipitates thus occurred by P o 2 increase. In contrast, when 95Al 2 O 3 ‐5Fe 2 O 3 specimens constituting only corundum grains were annealed under low P o 2 where both corundum and spinel phases are stable, grain boundaries migrated without spinel precipitation, leaving behind a corundum phase depleted of Fe 2 O 3 , similar to chemically induced grain‐boundary migration (CIGM) observed during solute depletion. The volatilization of Fe 2 O 3 appeared to cause the boundary migration without precipitation. The observed CIGM and DD would suggest various possibilities of microstructure control in other oxide systems through oxygen partial pressure change.