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Mechanical Behavior of MoSi 2 Reinforced–Si 3 N 4 Matrix Composites
Author(s) -
Petrovic John J.,
Pena Maria I.,
Reimanis Ivar E.,
Sandlin Michael S.,
Conzone Samuel D.,
Kung H. Harriet,
Butt Darryl P.
Publication year - 1997
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1997.tb03234.x
Subject(s) - materials science , composite material , fracture toughness , creep , phase (matter) , composite number , thermal expansion , microstructure , fracture (geology) , toughening , toughness , chemistry , organic chemistry
The mechanical behavior of MoSi 2 reinforced–Si 3 N 4 matrix composites was investigated as a function of MoSi 2 phase content, MoSi 2 phase size, and amount of MgO densification aid for the Si 3 N 4 phase. Coarse‐phase MoSi 2 ‐Si 3 N 4 composites exhibited higher room‐temperature fracture toughness than fine‐phase composites, reaching values >8 MP·am 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 >1000 MPa and impression creep rates of ∼10 −8 s −1 at 1200°C were observed. Increased MgO levels generally were deleterious to MoSi 2 ‐Si 3 N 4 mechanical properties. Internal stresses due to MoSi 2 and Si 3 N 4 thermal expansion coefficient mismatch appeared to contribute to fracture toughening in MoSi 2 ‐Si 3 N 4 composites.