PM1000 is an oxide dispersion strengthened (ODS) nickel based superalloy with applications in the aerospace and glass processing industries. It contains about 0.6 weight percent of incoherent finely dispersed yttria particles. Earlier work has addressed the high- temperature isothermal low-cycle fatigue (LCF) [
], creep [
] and oxidation [
] behaviour of PM1000. However, no known work has been done to characterize the thermomechanical fatigue (TMF) performance of this superalloy. The present work therefore involved a study of the high-temperature cyclic stress-strain response of PM1000 under isothermal fatigue (IF) and TMF loading conditions. Both IF and TMF tests were conducted in the temperature range from 450 to 950°C, with mechanical strain amplitudes varying from 0.35 to 0.5% in laboratory air conditions. The maximum mechanical strain and maximum temperature occurs simultaneously in in-phase (IP) TMF, while out-of-phase (OP) TMF has the maximum strain coinciding with minimum temperature.