Atomic-Scale Insights into the Precipitation Behaviors of Copper Atoms in Liquid Lithium

•The Cu atoms combine with Li atoms to form CuLix nanoalloy clusters during their precipitation process.•The low temperature environment not only facilitates the formation of large clusters but also promotes their transformation from amorphous structures to ordered Cu-Li solid solutions.•The merger and growth of clusters reduce the potential energy of inner atoms and accelerate the release of latent heat from phase transition.•The CuLix nanoalloy clusters bound Li atoms through alloying and surface adsorption and increased the viscosity of liquid Li.