日本金属学会誌

J. Japan Inst. Met. Mater, Vol. 81, No. 05 (2017),
pp. 264-269

Influence of Zn Addition on the Solid/Liquid Interfacial Energy in Sn-Ag Alloy

R. Yoshimura 1, H. Esaka 1 and K. Shinozuka 1

1 Department of Materials Science and Engineering, National Defense Academy of Japan

Abstract:

In order to assess the effect of Zn addition in Sn-2Ag alloy on the undercooling of the primary (β-Sn) phase, tip radii of the columnar dendrites of primary (β-Sn) have been systematically investigated. Sn-2Ag-x Zn alloys were prepared for the experiments, where x=0, 0.05 and 0.6 mass%. These alloys were unidirectionally solidified at growth velocities of 4, 10, 20, 30 and 40 μm/s. The tip radii of columnar dendrites of primary (β-Sn) on the longitudinal cross section of quenched samples were characterized. It was found that the tip radius decreased with increasing growth velocity and with increasing amounts of Zn. The effect of Zn addition on the solid/liquid interfacial energy was analyzed by assuming that the addition of Zn to Sn-2Ag alloy will not change the physical parameters such as the diffusion coefficient of the solute, solidification temperature range, and entropy of fusion. The addition of small amounts of Zn may considerably decrease the solid/liquid interfacial energy of primary (β-Sn). This may possibly decrease the undercooling for nucleation of the primary (β-Sn) phase in Sn-2Ag-x Zn alloy.

[doi:10.2320/jinstmet.J2016048]


(Received 2016/08/29)

Keywords:

solid-liquid interfacial energy, unidirectional solidification, dendrite tip radius, columnar dendrite, nucleation, primary (β-tin)


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