Grain boundaries in titania-doped {alpha}-alumina with anisotropic microstructure

Journal Article · Sat Nov 01 04:00:00 EST 1997 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1997.tb03198.x· OSTI ID:556430

Kebbede, A; Messing, G L; Carim, A H ^[1]

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1. Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

The microstructure of sol-gel-derived {alpha}-alumina (Al{sub 2}O{sub 3}) doped with 0.6 wt% titania, sintered at 1450 C for 1 h, consisted of thin platelets with (0001) faces in a matrix of equiaxed grains. Short facets at the edges of the platelets developed primarily parallel to the {l_brace}10{bar 1}2{r_brace} planes, while some were parallel to the {l_brace}11{bar 2}3{r_brace} planes; other edges showed irregular, curved boundaries. The basal surfaces of the platelets were coated with thin layers (0.5--6 nm) of an amorphous titanium-containing aluminosilicate phase, which also was present at triple points. No amorphous phase was found on the short faceted boundaries, on curved boundaries at platelet edges, or at grain boundaries of equiaxed, matrix grains. However, titanium enrichment was observed at all examined boundaries, suggesting that titanium segregation alone did not account for the development of anisotropic microstructure. Curved incursions on basal facets were associated with occasional particles of aluminum titanate (Al{sub 2}TiO{sub 5}).

• Sponsoring Organization: Office of Naval Research, Washington, DC (United States)
• OSTI ID: 556430
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 11 Vol. 80; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
ANISOTROPY
CHEMICAL COMPOSITION
GRAIN BOUNDARIES
MICROSTRUCTURE
SAMPLE PREPARATION
SEGREGATION
SINTERING
TITANIUM ADDITIONS