Published online by Cambridge University Press: 15 February 2011
Fiber push-out tests were used to evaluate several double coating systems for sapphire fibers in γ -TiAl. The double coatings consisted of an inner debond coating, followed by an outer coating of alumina that serves as a diffusion barrier. The inner coatings were of three types: carbon black, colloidal graphite and porous alumina. By comparing estimates of interface toughness computed from the push-out tests, each double coating is found to permit debonding and sliding of the sapphire fibers. Consequently, each of the double coatings would afford improved fracture toughness for sapphire reinforced γ -TiAl.