Microstructure Evolution and Mechanical Properties of Novel γ/γ′ Two-Phase Strengthened Ir-Based Superalloys

• Published in: Metals (Basel ) Vol. 9; no. 11; p. 1171
• Main Authors: Fang, Xiao, Hu, Rui, Yang, Jieren, Liu, Yi, Wen, Ming
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2019
• Subjects: Alloys; Compressive strength; Cooling; Evolution; Homogenization; Investigations; ir-based alloys; Mechanical properties; Microstructure; Morphology; Nanoindentation; Phase relationships; Precipitation hardening; Quaternary alloys; Room temperature; Solid phases; Solid solutions; Solidification; Solution strengthening; Superalloys; Tungsten base alloys; ultrahigh-temperature; γ/γ′ two-phase; Germany
• DOI: 10.3390/met9111171
• ISSN: 2075-4701

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.