Crystallographic and Morphological Evidence of Solid–Solid Interfacial Energy Anisotropy in the Sn-Zn Eutectic System

Abstract

In this paper, we explore the morphological evolution during two-phase growth in the Sn-Zn eutectic system, which has a particularly low volume fraction of the minority Zn phase. The reason for this choice is its exotic nature, as even with such a low volume fraction, the reported morphology is ''broken-lamellar,'' in contrast to the usually expected hexagonal arrangement of Zn rods in the Sn matrix. Thus, the main objective of the study is to investigate the reasons behind this phenomenon. We begin by presenting experimental results detailing the morphology and crystallography of the eutectic microstructures under various combinations of thermal gradients and velocities in directional solidification conditions. Based on the crystallography and further specially designed experiments we find that the solid-solid interface between the Sn and Zn crystal is anisotropic. On the basis of the results, we propose a hypothesis that the presence of solid-solid interfacial energy anisotropy leads to the formation of predominantly broken-lamellar structures, even when the minority fraction is significantly low.

Pseudo-4D view of the growth and form of crystallographically ‘locked’ eutectic colonies

“…What is the influence of the velocity transients on microstructure evolution? As a starting point, we calculate the time-dependent lamellar spacing using methods described elsewhere [18]. In response to the oscillations in interfacial velocity 𝑉, the lamellar spacing 𝜆 fluctuates out-ofphase (Figure 3(b)), as would be predicted by theory on univariant eutectics [19].…”

Anisotropy of Microstructure and Its Influence on Thermoelectricity: The Case of Cu2Te–Sb2Te3 Eutectic

“…The temperature gradient at the melting point of the eutectic is calculated using the axial temperature plot and is 23.4 K/mm. More details about the apparatus are given in refs and . We have varied the solidification rates by changing the apparatus’ traverse rate relative to the stationary sample using a gearbox coupled with a linear drive.…”

Lamella-rod pattern transition and confinement effects during eutectic growth

“…The SCN-DC system also presents the advantage, in the present context, that most eutectic grains can be considered as essentially isotropic (for a study of the effect of a strong interfacial anisotropy on the lamella-rod transition, see, e.g., Ref. [32]). Here, directional solidification experiments were carried out using a series of flat, glass-wall samples with various values of the thickness δ between 15 (thin samples) and 350 µm (thick samples).…”