Mechanical behavior of MoSi{sub 2} reinforced-Si{sub 3}N{sub 4} matrix composites

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Journal of the American Ceramic Society

OSTI ID:605757

Petrovic, J J; Pena, M I; Reimanis, I E; Sandlin, M S; Conzone, S D; Kung, H H; Butt, D P ^[1]

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1. Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

The mechanical behavior of MoSi{sub 2} reinforced-Si{sub 3}N{sub 4} matrix composites was investigated as a function of MoSi{sub 2} phase content, MoSi{sub 2} phase size, and amount of MgO densification aid for the Si{sub 3}N{sub 4} phase. Coarse-phase MoSi{sub 2}-Si{sub 3}N{sub 4} composites exhibited higher room-temperature fracture toughness than fine-phase composites, reaching values > 8 MPa {center_dot} m{sup 1/2}. Composite fracture toughness levels increased at elevated temperature. Fine-phase composites were stronger and more creep resistant than coarse phase composites. Room-temperature strengths > 1,000 MPa and impression creep rates of {approximately} 10{sup {minus}8} s{sup {minus}1} at 1,200 C were observed. Increased MgO levels generally were deleterious to MoSi{sub 2}-Si{sub 3}N{sub 4} mechanical properties. Internal stresses due to MoSi{sub 2} and Si{sub 3}N{sub 4} thermal expansion coefficient mismatch appeared to contribute to fracture toughening in MoSi{sub 2}-Si{sub 3}N{sub 4} composites.

• Sponsoring Organization: USDOE, Washington, DC (United States); Office of Naval Research, Washington, DC (United States)
• OSTI ID: 605757
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 12 Vol. 80; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
CREEP
FRACTURE PROPERTIES
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
MOLYBDENUM SILICIDES
PHASE STUDIES
SILICON NITRIDES
THERMAL EXPANSION