Effects of Ta on Microstructure and Mechanical Properties of Novel γ+γ＇ Two-Phase Ir-Based Superalloys

Abstract:

γ＇-Ir3(Al,W) phase-strengthed Ir-13W-6Al(at.%) Superalloys exhibit promising applications for aerospace industry. An experimental set-up was based on Ir-13W-6Al ternary superalloy and 2, 5, 8 at.% Ta elements were added. In order to research the effect of Ta, the microstructure evolution, the amount of γ＇ strengthening phase, the precipitation behavior, room-/high- temperature mechanical properties and fracture characteristics of γ+γ＇ two-phase Ir-based superalloys were investigated. The results show that with Ta content increasing, the volume fraction of γ＇strengthening phase increases and the vickers hardness/nano-hardness are higher than the Ir-13W-6Al ternary superalloy. The addition of Ta improves the high-temperature mechanical properties of Ir-13W-6Al superalloys at 1300 ℃, and the increased compressive strength can be attributed to the precipitation of γ＇-Ir3(Al,W) phase and solid-solution strengthening. Ta effectively improves the room- and high-temperature properties of Ir-13W-6Al superalloys. This study provides experimental and theoretical guide for the development of novel γ+γ＇ two-phase Ir-based superalloys.

Key words:Ir-based superalloys; γ＇-Ir3(Al,W) phase; microstructure; solid-solution strengthening; mechanical properties