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The present work introduces a novel γ\'phase-strengthened Ir-W-Al-Th superalloy for ultrahigh-temper-ature applications.First,the as-cast microstructure and phase transformation of Ir-13W-6Al-0.15Th (at％) alloy during solid solution and aging were investigated.Phase transformation was observed during heat treatment.The primary γ\'phase disappeared via the redissolution of γ\'→ γ at 1800 ℃.The recrystallization took place at 1450 ℃ and very fine equiaxed γ\'/γ grains formed after 240 h.The cold-rolled microstructure indicated that the room-temperature γ phase was brittle and cracks mainly emerged along grain boundaries.Ir-13W-6Al-0.15Th alloy exhibited a higher nanohardness than other Ir-based superalloys and pure Ir,which can be attributed to the solid solution and precipitation (γ\') strengthening.In addition,the as-cast Ir-13W-6Al-0.15Th alloy shows a medium room-temperature compressive yield strength and good ductility.