The roles of amorphous grain boundaries and the {beta}-{alpha} transformation in toughening SiC
- Lawrence Berkeley National Lab., CA (United States). Center for Advanced Materials
- Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering
Controlled development of the ceramic microstructure has produced silicon carbide (SiC) with a toughness three times that of a commercial SiC, Hexoloy-SA, coupled with > 50% improvement in strength. Al, B and C were used as sintering additives, hence the designation ABC-SiC. These additives facilitated full densification at temperature as low as 1,700 C, the formation of an amorphous phase at the grain boundaries to enhance intergranular fracture, and the promotion of an elongated microstructure to enhance crack deflection and crack bridging. Comparisons of microstructures and fracture properties have been made between the present ABC-SiC, Hexoloy-SA and other reported SiC ceramics sintered with YAG or Al{sub 2}O{sub 3}. The Al-O chemistry of the amorphous phase in the ABC-SiC accounted for the intergranular fracture vs the transgranular fracture in Hexoloy-SA. An interlocking plate-like grain structure developed during the {beta} to {alpha} transformation without limiting densification. The combined microstructural developments improved both strength and toughness.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 616390
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 46; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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