Materials characterization of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites. Part 1: Tensile and fatigue behavior

Journal Article · Fri Dec 01 04:00:00 EST 1995 · Metallurgical Transactions, A

DOI:https://doi.org/10.1007/BF02669451· OSTI ID:205256

Liaw, P K ^[1]; Diaz, E S ^[2]; Chiang, K T; Loh, D H ^[3]

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1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
2. Westinghouse Science and Technology Center, Pittsburgh, PA (United States)
3. Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.

Flexural fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-ply, continuous silicon carbide (SiC) fibers. The titanium composites had an eight-ply (0, 90, +45, {minus}45 deg) symmetric layup. Fatigue life was found to be sensitive to fiber layup sequence. Increasing the test temperature from 24 C to 427 C decreased fatigue life. Interface debonding and matrix and fiber fracture were characteristic of tensile behavior regardless of test temperature. In the tensile fracture process, interface debonding between SiC and the graphite coating and between the graphite coating and the carbon core could occur. A greater amount of coating degradation at 427 C than at 24 C reduced the Ti/SiC interface bonding integrity, which resulted in lower tensile properties at 427 C. During tensile testing, a crack could initiate from the debonded Ti/SiC interface and extend to the debonded interface of the neighboring fiber. The crack tended to propagate through the matrix and the interface. Dimpled fracture was the prime mode of matrix fracture. Interface debonding, matrix cracking, and fiber bridging were identified as the prime modes of fatigue mechanisms. To a lesser extent, fiber fracture was observed during fatigue. However, fiber fracture was believed to occur near the final stage of fatigue failure. In fatigued specimens, facet-type fracture appearance was characteristic of matrix fracture morphology. Theoretical modeling of the fatigue behavior of Ti/SCS-6 composites is presented in Part 2 of this series of articles.

• Sponsoring Organization: USDOE
• OSTI ID: 205256
• Report Number(s): CONF-940204--
• Journal Information: Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 12 Vol. 26; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
AEROSPACE INDUSTRY
CHROMIUM ALLOYS
COMPOSITE MATERIALS
CRACK PROPAGATION
CRACKS
FATIGUE
FIBERS
FRACTOGRAPHY
HOT PRESSING
INTERFACES
MORPHOLOGY
SAMPLE PREPARATION
SILICON CARBIDES
TENSILE PROPERTIES
TITANIUM BASE ALLOYS
VANADIUM ALLOYS