# Solidification of liquid metal drops during impact

## TL;DR

This study investigates how liquid metal drops solidify during impact on cold substrates, revealing the influence of solidification on spreading patterns and impact outcomes through experiments and phase diagrams.

## Contribution

It provides new experimental insights into the solidification process during liquid metal impact and introduces a phase diagram relating impact conditions to outcomes.

## Key findings

- Radial ligament patterns rapidly solidify from the center.
- Solidification influences the final morphology of the splat.
- Phase diagram maps impact outcomes to temperature and velocity.

## Abstract

Hot liquid metal drops impacting onto a cold substrate solidify during their subsequent spreading. Here we experimentally study the influence of solidification on the outcome of an impact event. Liquid tin drops are impacted onto sapphire substrates of varying temperature. The impact is visualised both from the side and from below, which provides a unique view on the solidification process. During spreading an intriguing pattern of radial ligaments rapidly solidifies from the centre of the drop. This pattern determines the late-time morphology of the splat. A quantitative analysis of the drop spreading and ligament formation is supported by scaling arguments. Finally, a phase diagram for drop bouncing, deposition and splashing as a function of substrate temperature and impact velocity is provided.