Mechanical Behavior of MoSi2 Reinforced–Si3N4Matrix Composites |
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| Authors: | John J Petrovic Maria I Pena Ivar E Reimanis Michael S Sandlin Samuel D Conzone H Harriet Kung Darryl P Butt |
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| Affiliation: | Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico |
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| Abstract: | The mechanical behavior of MoSi2 reinforced–Si3N4 matrix composites was investigated as a function of MoSi2 phase content, MoSi2 phase size, and amount of MgO densification aid for the Si3N4 phase. Coarse-phase MoSi2-Si3N4 composites exhibited higher room-temperature fracture toughness than fine-phase composites, reaching values >8 MP·am1/2. Composite fracture toughness levels increased at elevated temperature. Fine-phase composites were stronger and more creep resistant than coarse phase composites. Room-temperature strengths >1000 MPa and impression creep rates of ～10?8 s?1 at 1200°C were observed. Increased MgO levels generally were deleterious to MoSi2-Si3N4 mechanical properties. Internal stresses due to MoSi2 and Si3N4 thermal expansion coefficient mismatch appeared to contribute to fracture toughening in MoSi2-Si3N4 composites. |
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