High temperature fracture toughness of single crystal yttrium-aluminium garnet
- Los Alamos National Lab., NM (United States)
Y{sub 3}Al{sub 5}O{sub 12} (YAG) is the most creep-resistant single crystal oxide known and is therefore an attractive candidate for very high temperature applications. The fracture toughness, K{sub 1c}, was measured as a function of temperature using the single edge precracked beam (SEPB) method and was compared to notched beam method results in the literature. The fracture toughness of annealed SEPB specimens was found to be independent of both temperature from 20 C to at least 1,700 C and loading rate over two orders of magnitude. Thus the brittle-to-ductile transition does not occur before 1,700 C. Previous reports of remarkable increases in the fracture toughness below 1,700 C using notched beam methods are considered erroneous due to microcrack healing and crack blunting effects. The SEPB fracture toughness method avoids these problems since a long, sharp crack exists in the specimen prior to testing and can be effectively preserved at high temperatures using a preloading procedure.
- OSTI ID:
- 524554
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
Similar Records
Some microstructural conditions for evaluating fracture toughness and R-curve behavior in platelet-reinforced composites
Further investigation of critical events in cleavage fracture of C-Mn base and weld steel