Study of the low cyclic behaviour of the IRIS alloy at high temperature

This paper presents experimental results on low cycle fatigue (LCF) behaviour at high temperatures of the IRIS alloy (Ti-Al-48-W-2-B-0.(08), at. %) densified by Spark Plasma Sintering (SPS). Cyclic stability is noticed, whatever the temperature and the total strain amplitude. Fracture occurs by mixed interlamellar and translamellar modes. Transmission electron microscopy (TEM) observations reveal that deformation is mainly due to ordinary dislocations and twins, and slip and cross-slip mechanisms have been clearly evidenced, without significant contribution of climb at 800 degrees C. It has also been established that dislocation density depends on fatigue life time rather than on stress amplitude.