THE EFFECT OF MICROSTRUCTURE ON THE OXIDATION BEHAVIOR OF TIAL-BASED INTERMETALLICS

The oxidation behaviour of three TiAl-based intermetallics, Ti-47Al-2Cr, Ti-48Al-5Cr and Ti-48Al-5Ni, in Ar-20%O2 at 900-degrees-C was investigated. The main emphasis was placed on the effect of alloy microstructure on the oxidation behaviour. It was found, that, depending on the exact composition, the oxidation resistance of TiAl-based intermetallics is strongly affected by the amount and distribution of the various phases which are present in the alloy. The oxide scale growth rates depends on the actual manufacturing process and subsequent heat treatment procedures. The differences imparted by these factors can be much larger than the effects imparted by ternary or quaternary alloying additions.