Nucleation of One Single Sn Droplet on Al Thin Film Explored by Nanocalorimetry

In order to investigate the nucleationNucleation process of micro-nano scale droplet in non-equilibrium state, it is necessary to obtain the thermodynamic parameters of rapid phase transition during the solidification process. In addition, the matrix can play a significant role in the solidification nucleationNucleation of the metals. In this paper, the nucleationNucleation process of one single Sn droplet on the surface of Al film was studied by nanocalorimetryNanocalorimetry. The results showed that the surface roughness of Al thin filmAl thin film prepared by magnetron sputtering was about 11.9 nm. With the cooling rateCooling rate increasing from 5 to 10,000 K/s, the undercoolingUndercooling enlarges from 96 to 104 K. However, the undercoolingUndercooling kept nearly unchanged irrespective of the overheatingOverheating extending from 5 to 120 K. In this case, the nucleationNucleation of the Sn droplet is triggered by Sn/Al interface structureStructure, which is nearly independent on the overheatingOverheating.