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 new class 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 and solid solution strengthening. The microstructure and mechanical properties of Ir−Al−W−Ta quaternary alloys exhibit promising characteristics for the development of high-temperature materials.

Keywords

• ir-based alloys
• ultrahigh-temperature
• γ/γ′ two-phase
• solution strengthening
• mechanical properties