In situ High-resolution Electron Microscope Observation of Phase Change in Nanometer-sized Alloy Particles

From the study of alloy phase formation in nanometer-sized particles by in situ transmission electron microscopy, it is revealed that not only the surface energy but also the interface energy of an interface between two different phases (solid–solid or solid–liquid) significantly changes the phase equilibrium of nanometer-sized particles. These energies result in large suppression of the eutectic point, structural instability, and unique solid/liquid two-phase structures in isolated nanometer-sized alloy particles. A theoretical study based on thermodynamics, which is modified in such a manner that Gibbs free energies for bulk materials were modified by taking factors affecting the phase equilibrium of nanometer-sized alloy particles into consideration, was proved useful to evaluate the results obtained from experiments.