Grain boundary devitrification of Ca α-sialon ceramics and its relation with the fracture toughness

Research output: Contribution to journalArticle

Abstract

Grain boundary devitrification was carried out on three Ca α-sialon ceramics with different grain sizes and morphologies and various amounts of grain boundary glass. The devitrified product was gehlenite in all samples, indicating that the crystallization of the Ca oxynitride glass was accompanied by a volume reduction. The volume reduction upon crystallization and the thermal expansion mismatch between the devitrified product and α-sialon grains would result in tensile residual stresses located at multi-grain junctions. These residual tensile stresses were expected to promote the crack deflection and bridging mechanism and thus to improve the material toughness. However, indentation fracture toughness measurement and scanning electron microscope study showed that there was no significant difference in fracture toughness and the fracture mode in present samples prior to and post heat treatment. This may be attributed to a change in the chemistry of the residual glass as a result of the grain boundary devitrification, which could enhance the bonding strength between the adjacent α-sialon grains. The enhanced bonding strength could have to some degree hindered the crack deflection and bridging mechanism.

Original languageEnglish (US)
Pages (from-to)1359-1364
Number of pages6
JournalJournal of Materials Science
Volume38
Issue number6
DOIs
StatePublished - Mar 15 2003

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Fracture toughness
Grain boundaries
Crystallization
Tensile stress
Glass
Residual stresses
Cracks
Indentation
Toughness
Thermal expansion
Electron microscopes
Heat treatment
Scanning

ASJC Scopus subject areas

  • Materials Science(all)

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Grain boundary devitrification of Ca α-sialon ceramics and its relation with the fracture toughness. / Zhang, Yu.

In: Journal of Materials Science, Vol. 38, No. 6, 15.03.2003, p. 1359-1364.

Research output: Contribution to journalArticle

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