Acoustic emission and fiber damage in creep of a unidirectional SCS-6/Ti-15-3 metal matrix composite at 450 C

Journal Article · Wed Nov 30 23:00:00 EST 1994 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(94)90072-8· OSTI ID:6987792

Ohno, N; Okamoto, N ^[1]; Miyake, T ^[2]; Nishide, S; Masaki, S Jr ^[3]

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1. Nagoya Univ. (Japan). Dept. of Mechanical Engineering
2. Nagoya Municipal Industrial Research Inst. (Japan). Dept. of Electro-Mechanical Engineering
3. Ishikawajima-Harima Heavy Industries, Ltd., Tokyo (Japan). Aeroengine and Space Operations

Metal matrix composites (i.e., MMCs) have potentially for high temperature applications because of light weight, high stiffness and good heat resistance. Especially titanium alloy matrix composites reinforced with continuous SiC fibers are expected to have excellent applications at high temperature, and such MMCs have been tested under tensile, compressive and cyclic loadings to evaluate high temperature strength. The present authors performed creep tests of a unidirectional SCS-6/Ti-15-3 MMC at 450 C. They found that it exhibits creep deformation and rupture in longitudinal creep at stress levels much lower than the tensile strength though the reinforcing phase, SCS-6 by Textron, does not creep at the test temperature. This experimental result can be explained as follows: At high temperature, stress in the matrix is relaxed, and accordingly stress in the fibers is increased, as was analyzed by Goto and McLean. Then, fiber breakage may occur progressively, starting from the weakest fiber, and if a certain number of fibers are thus broken, overall rupture can be induced. It is obvious that this creep rupture takes place more easily under higher applied stress, and that it is promoted if the fibers suffer from damage such as cracking in the reaction zone, degradation of the coating layer, and so on. Monitoring of AE (i.e., acoustic emission) can be effective in verifying the creep rupture process mentioned above. Neu and Roman monitored AE during thermomechanical fatigue tests of a unidirectional SCS-6/TIMETAL[reg sign]21S MMC, and they showed how effective this method is. In the present work, first the authors monitored AE in creep tests of a 6-ply unidirectional SCS-6/Ti-15-3 MMC at 450 C. Then, to examine the damage evaluation based on AE monitoring, the authors observed fibers exposed by etching the outer matrix layers in the crept specimens.

• OSTI ID: 6987792
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 31:11; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
42 ENGINEERING
420500 -- Engineering-- Materials Testing
ACOUSTIC EMISSION TESTING
ACOUSTIC TESTING
ALLOYS
CARBIDES
CARBON COMPOUNDS
COMPOSITE MATERIALS
CREEP
DATA
EXPERIMENTAL DATA
INFORMATION
MATERIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
MECHANICAL TESTS
NONDESTRUCTIVE TESTING
NUMERICAL DATA
SILICON CARBIDES
SILICON COMPOUNDS
TESTING
TITANIUM ALLOYS
TITANIUM BASE ALLOYS