  This paper investigates the size effect on the coalescence process of
contacting nanoparticles. It is revealed by molecular dynamics that the
nanometer-sized surface curvature coupled with the effective melting
temperature exhibits a strong influence on the atom diffusion at the interface,
and is therefore critical to the coalescence time. This effect is particularly
pronouncing for surface curvatures below 20 nm. A phenomenological model is
derived from the melting-point reduction approach to describe the kinetic
process of nanowire coalescence and is validated against a variety of
simulation datasets. The quantitative correlation between the sample size, the
sintering temperature and the contact morphology evolution is demonstrated.
