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Influence of Interfacial Roughness on Fiber Sliding in Oxide Composites with La‐Monazite Interphases
Author(s) -
Davis Janet B.,
Hay Randall S.,
Marshall David B.,
Morgan Peter E. D.,
Sayir Ali
Publication year - 2003
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.1151-2916.2003.tb00016.x
Subject(s) - materials science , composite material , monazite , microstructure , eutectic system , equiaxed crystals , crystal twinning , oxide , composite number , crystallite , grain boundary , coating , metallurgy , paleontology , biology , zircon
Room‐temperature debonding and sliding of fibers coated with La‐monazite is assessed using a composite with a polycrystalline alumina matrix and fibers of several different single crystal (mullite and sapphire) and directionally solidified eutectic (Al 2 O 3 /Y 3 Al 5 O 12 and Al 2 O 3 /Y‐ZrO 2 ) compositions. These fibers provide a range of residual stresses and interfacial roughnesses. Sliding occurred over a debond crack at the fiber‐coating interface when the sliding displacement and surface roughness were relatively small. At large sliding displacements with relatively rough interfaces, the monazite coatings were deformed extensively by fracture, dislocations, and occasional twinning, whereas the fibers were undamaged. Dense, fine‐grained areas (10 nm grain size) resembling recrystallized microstructures were also observed in the most heavily deformed regions of the coatings. Frictional heating during sliding is assessed. Potential mechanisms for forming such microstructures at low temperature are discussed, and a parallel is drawn with the known resistance of monazite to radiation damage. The ability of La‐monazite to undergo both debonding and plastic deformation relatively easily at low temperatures may enable its use as a composite interface.