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Thermodynamics and liquid phase separation in the Cu–Co–Nb ternary alloys

Published online by Cambridge University Press:  31 January 2011

Cuiping Wang*
Affiliation:
Department of Materials Science and Engineering, College of Materials, and Research Center of Materials Design and Application, Xiamen University, Xiamen 361005, People’s Republic of China
Kiyohito Ishida
Affiliation:
Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
*
a)Address all correspondence to this author. e-mail: wangcp@xmu.edu.cn
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Abstract

This work first deals with the effect of Nb addition on the liquid phase separation in the Cu–Co system, which displays a metastable liquid miscibility gap. The isothermal sections at 800, 900, 1000, 1100, and 1200 °C in the Cu–Co–Nb system have been experimentally determined by optical microscopy, electron probe microanalysis, and x-ray diffraction on the equilibrated alloys, and the phase equilibria in the Cu–Co–Nb ternary system were thermodynamically assessed by using CALPHAD (Calculation of Phase Diagrams) method on the basis of the presently determined experimental data. Nb additions can stabilize the metastable liquid phase separation in the Cu–Co binary system and significantly increase its critical temperature. The solidified Cu–Co–Nb alloys appearing on the top-bottom separated microstructural morphology under low cooling rate while forming core-type macrostructural morphology under high cooling rate have been confirmed.

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Articles
Copyright
Copyright © Materials Research Society 2010

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