Investigation of Mechanical Field Effect on Liquid Metals

Abstract

Gallium-based liquid metals exhibit unique mechanical and interfacial properties, including low viscosity, high surface tension, and dynamic surface reactivity, enabling significant deformation, fragmentation, and transport under external stimuli. Despite their potential in particle synthesis and functional applications, the role of mechanical fields in governing their interfacial dynamics remains poorly understood. This thesis investigates the influence of mechanical fields on liquid metal behaviour, focusing on ultrasonication and electrically induced effects. Ultrasonication is shown to drive efficient fragmentation and particle formation, with alloy composition playing a critical role in modulating surface tension and cavitation dynamics. Minor alloying additions reduce interfacial energy, enhancing cavitation–interface interactions and producing smaller, more uniform particles. High-speed imaging reveals cavitation-driven surface eruptions and fragmentation as key mechanisms. The introduction of an external electric field during sonication further modifies liquid metal behaviour. Voltage-assisted sonication demonstrates that electrical bias alters interfacial tension, oxidation, and surface activity, leading to polarity-dependent fragmentation and distinct particle size distributions. These results highlight the role of electrochemical effects in tuning the mechanical response under dynamic excitation. Under static electric fields, liquid metals exhibit composition-dependent deformation, motion, and fragmentation governed by electrocapillarity and oxidation-induced interfacial gradients. The strong coupling between alloy composition and interfacial stresses dictates macroscopic behaviour. Overall, this work establishes a unified framework linking mechanical fields and interfacial phenomena in liquid metals, providing new insights for controlling particle generation and liquid metal dynamics in advanced material systems.