High Temperature Fretting Fatigue Behavior in an XD™ γ-base TiAl

Abstract

The plain and fretting fatigue behavior was studied of a γ-base TiAl intermetallics at 675°C in air. he TiAl material was produced by the XD™ process and had a nominal composition of Ti-47Al-2Nb-2Mn+0.8vol%TiB2. The contact material was Inconel 718. The reduction of fatigue strength by fretting was very small (around 20%) compared to metallic materials (30̃60%). The plain and fretting fatigue S-N curves were flat, which resembled the behavior of ceramic materials. The flat S-N curves are corresponding to the very steep crack growth curve reported for TiAl-based materials containing TiB2. A fretting fatigue crack nucleated in the very late stage of fatigue life (later than 0.75Nf), while it is known to nucleate in the very early stage of fatigue life (less than few percent of Nf) for steels. The fatigue lifetimes of this material were suggested to be determined by the cycles needed for nucleation of a crack rather than by crack propagation.

Effects of plasma surface Ta alloying on the tribology behavior of γ-TiAl

“…The weaknesses could not be ignored, and could vastly limit the application at high temperature. Kazuhisa Miyoshi found wear in the turbine engine reduced the service life, especially high temperature wear [4][5][6] . This could be attributed to a fact that during the use of the dovetail, metal surfaces inevitably came into contact, and high temperature wear were liable to occur under the load and high temperature, which was the potential safety hazard to the turbine engine (Fig.…”