Please use this identifier to cite or link to this item: doi:10.22028/D291-24579
Title: Microstructural characterization of Al2O3-SiC nanocomposites
Author(s): Schmid, Herbert K.
Aslan, Mesut
Assmann, Steffen
Nass, Rüdiger
Schmidt, Helmut K.
Language: English
Year of Publication: 1998
OPUS Source: Journal of the European Ceramic Society. - 18. 1998, 1, S. 39-49
SWD key words: Mikrostruktur
Aluminium oxydatum
Nanostrukturiertes Material
DDC notations: 620 Engineering and machine engineering
Publikation type: Journal Article
Abstract: Al2O3 composite ceramics containing 10 vol% SiC nanoparticles were prepared by pressureless sintering. SiC particles < 150 nm detach from the matrix grain boundaries during grain growth and are predominantly observed in intragranular positions, whereas larger SiC particles retain intergranular positions. Thermal expansion mismatch causes local residual tensile stresses in the matrix grains, giving rise to strain contrasts in TEM imaging; occasionally microcracking around intragranular inclusions &ge; 100 nm is observed in thin TEM foils. It appears that the volume fraction of intragranular SiC particles in the size range 100 < d < 150 nm should not exceed &asymp;0.5% in high strength/high toughness Al2O3-SiC nanocomposites. The interaction between propagating cracks and internal stress fields around intragranular inclusions forces a transgranular fracture mode. Grain boundary pinning by large intergranular SiC particles, in combination with solute drag inhibits matrix grain growth, while the presence of an amorphous phase at Al2O3 grain boundaries and Al2O3-SiC phase boundaries assists in densifi cation. Excess liquid phase is exuded from the interfaces during consolidation and accumulates in large pores, stabilized by the accidental agglomeration of large SiC particles.
Link to this record: urn:nbn:de:bsz:291-scidok-28853
Date of registration: 11-Jun-2010
Faculty: SE - Sonstige Einrichtungen
Department: SE - INM Leibniz-Institut für Neue Materialien
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