Finite size melting of spherical solid-liquid aluminium interfaces

TL;DR

This study investigates how the melting temperature of nano-sized spherical aluminium interfaces depends on size and shape, revealing that the melting point depression is influenced by the interface area to volume ratio rather than just size.

Contribution

It demonstrates that the depressed melting temperature of nano-sized aluminium interfaces depends on the interface area to volume ratio, not solely on the inverse radius.

Findings

Melting temperature depression scales linearly with inverse radius for fixed apex angles.

The proportionality constant varies significantly with apex angle.

The depressed melting temperature correlates with the ratio of interface area to molten volume.

Abstract

We have investigated the melting of nano-sized cone shaped aluminium needles coated with amorphous carbon using transmission electron microscopy. The interface between solid and liquid aluminium was found to have spherical topology. For needles with fixed apex angle, the depressed melting temperature of this spherical interface, with radius $R$, was found to scale linearly with the inverse radius $1/R$. However, by varying the apex angle of the needles we show that the proportionality constant between the depressed melting temperature and the inverse radius changes significantly. This lead us to the conclusion that the depressed melting temperature is not controlled solely by the inverse radius $1/R$. Instead we found a direct relation between the depressed melting temperature and the ratio between the solid-liquid interface area and the molten volume.