Influence of iridium on the properties of γ′-strengthened co-base superalloys

Bauer A, Neumeier S, Pyczak F, Göken M (2015)

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2015

Journal

Advanced Engineering Materials Wiley

Book Volume: 17

Pages Range: 748-754

Journal Issue: 6

DOI: 10.1002/adem.201400266

Abstract

The influence of iridium on the phase stability, oxidation behavior, and high temperature creep strength of γ′-hardened Co-base superalloys is discussed. Ir increases the γ′-solvus temperature and γ′-volume fraction since it partitions slightly to the γ′-phase. However, Ir leads also to a discontinuous precipitation transformation of the metastable γ/γ′-microstructure into a lamellar microstructure of Co3W, CoAl, and a Co-rich fcc phase for the W-rich alloys. A reduction of W in presence of Ir leads to a higher phase stability. The constrained lattice misfit between the γ and γ′ phase in the Ir and high W containing alloy is +0.5%. The alloying element Ir strongly increases the creep strength at 850°C as long as the γ/γ′-microstructure is not discontinuously transformed. Furthermore, the oxidation resistance is improved by the addition of iridium. Addition of Iridium to a γ′ strengthened Co-base superalloy leads to increased volume fraction and solvus temperature of the γ′ precipitate phase, as well as to higher solidus and liquidus temperatures. Iridium partitions slightly to the γ′ precipitate phase and the creep strength is improved considerably as long the γ/γ′-microstructure is not discontinuously transformed.

Authors with CRIS profile

Alexander Bauer Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften) Steffen Neumeier Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften) Mathias Göken Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)

Additional Organisation(s)

Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)

Related research project(s)

Single crystal y/y'-hardened Co-base superalloys - alloy development, heat treatment strategies and mechanical properties (B03) (SFB/TRR 103) SFB/TRR 103: Vom Atom zur Turbinenschaufel - wissenschaftliche Grundlagen für eine neue Generation einkristalliner Superlegierungen Jan. 1, 2012 - Dec. 31, 2015 GRK 1229: Stabile und metastabile Mehrphasensysteme bei hohen Anwendungstemperaturen April 1, 2006 - March 30, 2015

Involved external institutions

Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung GmbH (HZG) DE Germany (DE)

How to cite

APA:

Bauer, A., Neumeier, S., Pyczak, F., & Göken, M. (2015). Influence of iridium on the properties of γ′-strengthened co-base superalloys. Advanced Engineering Materials, 17(6), 748-754. https://doi.org/10.1002/adem.201400266

MLA:

Bauer, Alexander, et al. "Influence of iridium on the properties of γ′-strengthened co-base superalloys." Advanced Engineering Materials 17.6 (2015): 748-754.

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