Stress-rupture behavior of small diameter polycrystalline alumina fibers

Conference · Thu Apr 01 04:00:00 EST 1993

OSTI ID:5873706

Yun, H M; Goldsby, J C; Dicarlo, J A

Continuous length polycrystalline alumina fibers are candidates as reinforcement in high temperature composite materials. Interest therefore exists in characterizing the thermomechanical behavior of these materials, obtaining possible insights into underlying mechanisms, and understanding fiber performance under long term use. Results are reported on the time-temperature dependent strength behavior of Nextel 610 and Fiber FP alumina fibers with grain sizes of 100 and 300 nm, respectively. Below 1000 C and 100 hours, Nextel 610 with the smaller grain size had a greater fast fracture and rupture strength than Fiber FP. The time exponents for stress-rupture of these fibers were found to decrease from approximately 13 at 900 C to below 3 near 1050 C, suggesting a transition from slow crack growth to creep rupture as the controlling fracture mechanism. For both fiber types, an effective activation energy of 690 kJ/mol was measured for rupture. This allowed stress-rupture predictions to be made for extended times at use temperatures below 1000 C.

• Research Organization: National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center
• OSTI ID: 5873706
• Report Number(s): N-93-32382; NASA-TM--106256; E--7979; NAS--1.15:106256; CONF-930438--; CNN: RTOP 510-01-50
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COMPOSITE MATERIALS
CRACK PROPAGATION
CREEP
CRYSTALS
FAILURES
FATIGUE
FIBERS
FRACTURE MECHANICS
GRAIN SIZE
MATERIALS
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE
POLYCRYSTALS
REINFORCED MATERIALS
RUPTURES
SIZE
STRESS ANALYSIS
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
THERMAL FATIGUE
THERMODYNAMICS
TIME DEPENDENCE