Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

doi:10.1007/s40195-015-0253-5

Abstract

Abstract:

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid (Pb)/liquid (Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field (≤0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level (0.8-5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.

Key words: Microstructural, evolution, Crystallization, behavior, Dendrite, growth, Diffusion, behavior, Magnetic, field, Solidification, pattern

Lei Li, Bo Xu, Wei-Ping Tong, Hui Zhang, Chun-Yan Ban, Li-Zi He, Zhi-Hao Zhao, Yu-Bo Zuo, Qing-Feng Zhu, Jian-Zhong Cui. Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(6): 725-732.

Figures/Tables 9

Fig. 1 Schematic diagram of Pb/Sn diffusion couple preparation

Fig. 2 Schematic diagram of the experimental apparatus

Fig. 3 a OM images of the microstructures of Sn-10 wt% Pb specimen; b Sn dendrites in the upper part of the liquid (Pb)/liquid (Sn) couple; c the magnified image of the eutectic region in b

Fig. 4 Microstructures of the top Sn side of the Pb-Sn couples which were solidified under SMF of 0.1 T a, 0.3 T b, 0.5 T c and 0.8 T d

Fig. 5 Microstructures of the top Sn side of the Pb-Sn couples which were solidified under SMF of 1 T a, 3 T b, 5 T c and 12 T d

Fig. 6 a Composition profiles of the Pb atoms changing from the initial ① to the final ⑤ with time in the whole melt; b Pb atoms distribution in the whole melt corresponding to a composition profile of ④ where A, B and C represent hypereutectic region, eutectic region and hypoeutectic region, respectively

Fig. 7 Phase diagram of Pb-Sn alloy [19]

Fig. 8 a Composition profile in Sn melt; b schematic diagram of the crystallization starting from the top of Sn melt; c schematic diagram of β-Sn crystals growing downwards continuously; d schematic diagram of β-Sn crystals deflecting from the axial direction

Fig. 9 Microstructure of Pb-Sn alloy in the hypoeutectic region

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