Grain refinement in highly undercooled solidification of Ni85Cu15 alloy melt: Direct evidence for recrystallization mechanism

The grain refinement occurring upon rapid solidification of undercooled Ni85Cu15 alloy melts has been studied. Applying theoretical calculations for stress accumulation in dendritic skeletons, the grain refinement occurring with ΔT >∼180 K is ascribed to plastic deformation of dendrites and subsequent recrystallization. This has been evidenced directly using high-resolution transmission electron microscopy observation of the as-solidified granular crystals.