Fiber Coating Performance in TiAl

The interfacial chemical behavior of two candidate coating systems for use on fine diameter (∼10 μm) Al 2 O 3 in TiAl is presented. The performance of the Nb/Y 2 O 3 system appears to be related to the transport rate of Ti through the Y 2 O 3 layer. Interfacial reaction is then observed at points where the Y 2 O 3 thickness is less than about 1 μm. The main reaction product formed appears to be an oxygen saturated TiAl phase. An alternative system, C/TiN/Y 2 O 3 is then presented as a solution to the Ti transport problem and may offer more desirable interfacial mechanical properties.