Microstructure evolution and mechanical properties of novel γ/γ' two-phase strengthened Ir-based superalloys

Abstract

Ir-based superalloys are irreplaceable in some specific harsh conditions regardless of their cost and high density. In order to develop a newclass of Ir-based superalloy for future ultrahigh-temperature applications, the microstructure evolution, phase relationships, and mechanical properties of Ir-Al-W-Ta alloys with γ/γ' two-phase structure were investigated. Room- and high-temperature compressions at 1300 °C, and room-temperature nanoindentation for the Ta-containing Ir-6Al-13W alloys were conducted. The results show that the addition of Ta can significantly improve the high-temperature mechanical properties, but does not change the fracture mode of the Ir-based two-phase superalloys. The compressive strength of quaternary alloys can be attributed to the precipitation of γ'-Ir3(Al,W) phase andsolidsolution strengthening.Themicrostructure andmechanical properties of Ir-Al-W-Ta quaternary alloys exhibit promising characteristics for the development of high-temperature materials.