Oscillatory bifurcation patterns initiated by seeded surface solidification of liquid metals

Liquid metals are unique solvents in which elegant solidification patterns emerge. Despite the fundamental and technological importance of the solidification process, knowledge gaps and challenges exist in the direct observation, understanding and control of phase transition and pattern formation on the surface of liquid metals. Here, we report the emergence of oscillatory bifurcation solidification patterns in multiple alloy systems. In particular, the solidification of a model Ag0.001Ga0.999 alloy, triggered by controlled nucleation, reveals a switchable transition between branched and particulate surface patterns of nanoscale phase-separated intermetallic Ag2Ga. Evidence from solidification observations, surface analyses and molecular dynamics (MD) simulations suggests that surface contact phases and conditions modulate the instability dynamics, giving rise to the unconventional oscillatory bifurcation patterns. By demonstrating manipulation and applications in a number of settings enabled by our method, we highlight the wide implications of the observations and present possibilities for exploiting surface solidification phenomena for the synthesis of exclusive nanostructured functional patterns for surface-based applications.