Amorphous intergranular films in silicon nitride ceramics quenched from high temperatures

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb04019.x· OSTI ID:5727844

Cinibulk, M K; Kleebe, H; Schneider, G A; Ruehle, M ^[1]

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1. Inst. fuer Werkstoffwissenschaft, Stuttgart (Germany). Max-Planck-Inst. fuer Metallforschung

High-temperature microstructure of an MgO-hot-pressed Si[sub 3]N[sub 4] and a Yb[sub 2]O[sub 3] + Al[sub 2]O[sub 3]-sintered/annealed Si[sub 3]N[sub 4] were obtained by quenching thin specimens from temperatures between 1,350 and 1,550 C. Quenching materials from 1,350 C produced no observable exchanges in the secondary phases at triple-grain junctions or along grain boundaries. Although quenching from temperatures of [approximately]1,450 C also showed no significant changes in the general microstructure or morphology of the Si[sub 3]N[sub 4] grains, the amorphous intergranular film thickness increased substantially from an initial [approximately]1 nm in the slowly cooled material to 1.5--9 nm in the quenched materials. The variability of film thickness in a given material suggests a nonequilibrium state. Specimens quenched from 1,550 C revealed once again thin (1-nm) intergranular films at all high-angle grain boundaries, indicating an equilibrium condition. The changes observed in intergranular-film thickness by high-resolution electron microscopy can be related to the eutectic temperature of the system and to diffusional and viscous processes occurring in the amorphous intergranular film during the high-temperature anneal prior to quenching.

• OSTI ID: 5727844
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:11; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CERAMICS
CHALCOGENIDES
FABRICATION
MICROSTRUCTURE
NITRIDES
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PNICTIDES
QUENCHING
RARE EARTH COMPOUNDS
SILICON COMPOUNDS
SILICON NITRIDES
YTTERBIUM COMPOUNDS
YTTERBIUM OXIDES