Phase Selection in Undercooled Melts of Peritectic Cu-Ge Alloys

Abstract:

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Phase selection in undercooled melts of Cu-14.8Ge and Cu-18Ge compositions was investigated using the electromagnetic levitation technique in combination with substrate quenching and a drop tube. The results showed that the levitated and gas-cooled samples were all solidified into a microstructure consisting of primary -Cu plus peritectic -Cu5Ge. However, the samples quenched onto a copper substrate showed a segregation-free microstructure in the chilled zone, suggesting direct crystallization of the peritectic -Cu5Ge phase from a highly undercooled liquid. The Cu-18Ge samples quenched onto a glass substrate as well as those solidified in the drop tube also showed a segregation-free microstructure. An analysis of the nucleation kinetics revealed that the -Cu5Ge phase had a larger nucleation barrier than that of -Cu for all accessible undercoolings. It was suggested that phase selection in the undercooled Cu-Ge liquid might be controlled by transient nucleation kinetics.

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Periodical:

Edited by:

A. Roósz, V. Mertinger, P. Barkóczy and Cs. Hoó

Pages:

47-52

DOI:

10.4028/www.scientific.net/MSF.649.47

Citation:

J.R. Gao et al., "Phase Selection in Undercooled Melts of Peritectic Cu-Ge Alloys", Materials Science Forum, Vol. 649, pp. 47-52, 2010

Online since:

May 2010

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$35.00

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