The influence of the size effect on the transition of Au-Cu alloy nanoparticles to the dynamic amorphous state

Abstract

In this paper, the effect of size on the Au-Cu diagram for nanoparticles with a diameter of 1.5–20 nm is discussed. The first goal of the study is to obtain this phase diagram including the size-region of ultrasmall nanoparticles of Au–Cu alloy. It was found that the congruent melting point decreases with decreasing particle size. The second goal is to study the dependence of the critical diameter of nanoparticles and the critical temperature on the alloy composition. The thermodynamic conditions of the transition of ultra-small Au-Cu nanoparticles to the dynamic state were studied for the first time. It is shown that their critical diameter strongly depends on the alloy composition. The dependence of the critical diameter and critical temperature of nanoparticles on the alloy composition has a minimum due to congruent melting. The minimum critical diameter of the alloy nanoparticles is achieved at 1.5 nm approximately. The minimum critical temperature is about 390 K.