We present a molecular dynamics study of the diffusion phenomena in Ni2Y, transition-metal intermetallic phase via nearly-free-electron-tight-binding-bond interatomic interaction model. Interpretations of the dynamic structures from the calculations of the mean square displacements and spectral densities of velocity show that the rapid growth of this intermetallic phase found in the experimental study is mainly due to the high-rate self-diffusion in and near the grain-boundaries and independent of the vacancy. Therefore, the standard vacancy-based diffusion process is found to be not essential in this phase. (C) 1998 Elsevier Science S.A. All rights reserved.