Solid/liquid interface energy and its anisotropy of pure metals

Abstract

Solid/liquid (S/L) interface energy (𝛾_sl) and its anisotropy (φ) play a critical role in the understanding of nearly every single phenomenon that occurs during solidification of metals, such as nucleation, morphological instability and dendrite growth. However, due to difficulties associated with both experimental measurement and computer simulations, our current understanding of this topic is rather limited. In this work, a simple analytical model is developed to predict 𝛾_sl and φ for pure metals. This model suggests that S/L interface energy originates from atomic ordering in the S/L interface templated by the solid. 𝛾_sl can be expressed as the sum of contributions from both atomic layering (𝛾_z) and the in-plane atomic ordering ((𝛾_xy). Further analysis shows that 𝛾_sl for pure metals is determined by both heat of fusion per atom (∆𝐻_f<supa</sup>) and their crystal structures, while anisotropy depends only on crystal structure. The analytical model reveals that the physical origin of 𝛾_sl is atomic ordering in the S/L interface templated by the solid, while the physical origin of anisotropy is the difference in structural templating power between different crystal planes. It is demonstrated that the current analytical model is capable of predicting solid/liquid interface energy (𝛾_sl) and its anisotropy (φ) for any metallic element using parameters readily available in the literature.