Self-diffusion of Al and Pb atoms in Al–Pb immiscible alloy system

Al–Pb binary alloy system exhibits a positive heat mixing that precludes intermixing by conventional techniques, it is possible to achieve solid state alloying between these two immiscible elements in nanostructures by mechanical alloying (MA). The studies of detailed atomistic diffusion process of dynamic movement for Al and Pb were carried out by computer simulation, in conjunction with modified analytic embedded atom method (MAEAM). Computational results have clarified that the nearest-neighbor diffusion path is the dominant jump vector for both Al and Pb atom diffusion. The migration energies along this path have been estimated to be 0.35083 and 0.10538 eV, respectively. The self-diffusion activation energies for Al and Pb along NN jump are 0.99557 and 0.85919 eV, respectively. The calculated results reveal that Pb atom diffuses much faster than Al atom does, which concluded that Pb atom is the diffusive species in Al–Pb immiscible alloy system. The calculated self-diffusion activation energies for nano-sized Al and Pb grains are 0.83192 and 0.70455 eV, respectively. They are lower than that for normal sized Al and Pb grains, which facilitates the atomic diffusion and alloying during MA process in Al–Pb immiscible alloy system.