Observation of the formation of liquid droplets in steep temperature gradients

Abstract

Rods of a homogenized coarse-grained Al-4wt.%Cu alloy were subjected for a short time (in the order of seconds) to a steep temperature gradient and (partial) melting. θ-phase or eutectic particles are visible in the resolidified micros true ture. These microstructural features are interpreted as traces of former liquid regions, particularly intragranular liquid droplets. The former droplets were characterized with respect to their morphology and size. The bimodal size distribution indicates two classes of nucleation sites in the solid.