The early atomic-scale dissolution behavior of Cu in a molten pure Sn was studied by transmission electron microscope (TEM). The innermost region adjacent to the Cu lattice is an amorphous Cu-sn diffusion zone that contains dispersed epsilon-Cu3Sn nanocrystalline cells. The zigzag morphology reveal between Cu lattice and amorphous Cu-Sn diffusion zone. The height of step is about 0.2-1.1 nm on the terrace. The formation of zigzag morphology is initiated by preferential removal of Cu atoms from the kink sites on the crystal surface. The dissolved atoms form an amorphous Cu-Sn diffusion zone. This diffusion zone is a non-saturated state prior to further formation of crystalline cell. (c) 2005 Elsevier B.V. All rights reserved.