Grain-boundary migration in nonstoichiometric solid solutions of magnesium aluminate spinel 2; Effects of grain-boundary nonstoichiometry

Journal Article · Tue May 01 04:00:00 EDT 1990 · Journal of the American Ceramic Society; (USA)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb05172.x· OSTI ID:6067003

Chiang, Y M ^[1]; Kingery, W D ^[2]

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1. Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Materials Science and Engineering
2. Arizona Univ., Tucson, AZ (USA)

The grain-boundary chemistry of magnesium aluminate spinel solid solutions MgO {center dot} nAl{sub 2}O{sub 3} has been investigated in order to understand the mechanism of grain-boundary migration. It is found that although segregation of impurity Ca and Si is common, much larger deviations in grain-boundary stoichiometry are present. There is an excess of Al and O relative to Mg at grain boundaries in all compositions. Grain-boundary migration appears to be rate-limited by solute drag from intrinsic defects accommodating lattice nonstoichiometry, rather than by extrinsic solutes, consistent with the observed impurity tolerance of grain-boundary mobility. Different rate-limiting defects are proposed for magnesia-rich and alumina-rich spinels.

• OSTI ID: 6067003
• Journal Information: Journal of the American Ceramic Society; (USA), Journal Name: Journal of the American Ceramic Society; (USA) Vol. 73:5; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CALCIUM
CHALCOGENIDES
CHEMICAL COMPOSITION
CRYSTAL STRUCTURE
DIFFUSION
DISPERSIONS
DRAG
ELEMENTS
GRAIN BOUNDARIES
IMPURITIES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
METALS
MICROSTRUCTURE
MINERALS
MIXTURES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SEMIMETALS
SILICON
SOLID SOLUTIONS
SOLUTES
SOLUTIONS
SPINELS