Classical dynamical simulation of spontaneous alloying

"Spontaneous alloying" observed by Yasuda, Mori ct al. for metallic small c lusters is simulated using classical Hamiltonian dynamics. Very rapid alloy ing occurs homogeneously and cooperatively starling from the solid phase of the cluster if the heat of solution is negative and the size of cluster is less than a critical size. Analysis of 2D models reveals that the alloying rate obeys an Arrhenius-type law, which predicts the alloying time much le ss than second at room temperature. Evidences manifesting that the spontane ous alloying proceeds in the solid phase without melting are also presented . The simulation reproduces the essential features of the experiments.