Creep Strength and Microstructure of Polycrystalline γ′ - Strengthened Cobalt-Base Superalloys

Bauer A, Neumeier S, Pyczak F, Göken M (2012)

Publication Language: English

Publication Status: Published

Publication Type: Conference contribution, Original article

Publication year: 2012

Publisher: John Wiley and Sons

Pages Range: 695-703

ISBN: 9780470943205

DOI: 10.1002/9781118516430.ch77

Abstract

The influence of several alloying elements on the microstructure and creep properties of polycrystalline Co-base superalloys hardened with the ternary Ll2 compound, γ'-Co3(Al,W), are presented in this work. The stability of the γ/γ'-microstructure was investigated by long term aging at temperatures of 750 C° and 900 C°. High contents of chromium and iron destabilize the γ/γ'- microstructure. Additions of nickel widen the γ/γ'- two phase field. Discontinuous precipitation is observed only in the iridiumcontaining alloy during aging. In all other alloys no formation of further intermetallic phases are found even after 1000 hrs aging at 750 C° and 900 C°. Boron has been added for the formation of grain boundary strengthening intermetallic phases which leads to an adjacent γ'-depleted zone. Nanoindentation shows that titanium improves its hardness. The creep strength of the studied alloys is sufficiently better than that of commercial carbide hardened polycrystalline Co-base superalloys and already close to γ'- hardened Ni-base superalloys. An alloy containing 2 at.% titanium exhibited a creep strength comparable with the Ni-base alloy IN 100. The microstructure after creep tests at 950 C° showed rafting perpendicular to the compressive load axis, confirming the positive lattice misfit of the alloys at high temperatures which was determined with high energy X-ray diffraction. © 2012 The Minerals, Metals, & Materials Society. All rights reserved.

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)

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. (2012). Creep Strength and Microstructure of Polycrystalline γ′ - Strengthened Cobalt-Base Superalloys. (pp. 695-703). John Wiley and Sons.

MLA:

Bauer, Alexander, et al. "Creep Strength and Microstructure of Polycrystalline γ′ - Strengthened Cobalt-Base Superalloys." John Wiley and Sons, 2012. 695-703.

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