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Alloying Effects on the Stability of γ/γ′ Microstructure in Co-Al-W Base Alloys

Published online by Cambridge University Press:  16 March 2011

Yuki Tsukamoto ,
Satoru Kobayashi  and
Takayuki Takasugi
Yuki Tsukamoto
Affiliation:
Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
Satoru Kobayashi
Affiliation:
Osaka Center for Industrial Materials Research, Institute for Materials Research, Tohoku University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
Takayuki Takasugi
Affiliation:
Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan Osaka Center for Industrial Materials Research, Institute for Materials Research, Tohoku University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
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Abstract

The aim of this study is two-fold: first we reexamine the thermodynamic stability of γ’-Co3(Al,W) phase in the Co-Al-W ternary system. Secondly, we investigate the effect of a fourth alloying element (Ti or Ta) on the thermodynamic stability of the γ’ phase through microstructure observation, DSC measurement and EPMA analysis. Coarsened areas with γ/CoAl/Co3W phases are formed after annealing at 900 ºC for 2000 h in Co-Al-W ternary alloys with different Al/W ratios, which confirms that the three phases are in equilibrium with each other and that the γ’ phase is metastable at this temperature. The addition of a fourth alloying elements does not drastically change the microstructure formed after long term annealing at 900 ºC, indicating that the alloying elements do not improve the stability of the γ’ phase.

Keywords

phase equilibriaComicrostructure
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1295: Symposium N – Intermetallic-Based Alloys for Structural and Functional Applications , 2011 , mrsf10-1295-n05-24
Copyright
Copyright © Materials Research Society 2011

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References

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