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_{:The characteristics of iridium and the possible mechanisms of the brittle fracture of pure iridium in room temperature are generally discussed and it also describes the problems exited in the application of pure iridium in ultra-high temperature.The research ideas as well asas-obtained research results on the diversification of iridium alloys athome and abroad are systematically reviewed in this paper. Finally the future development propectsof iridium alloys used in the ultra-high temperature are presentedand it also point out the research directionsin the future.}