We predict a strongest size for the contact strength when asperity radii of
curvature decrease below ten nanometers. The reason for such strongest size is
found to be correlated with the competition between the dislocation plasticity
and surface diffusional plasticity. The essential role of temperature is
calculated and illustrated in a comprehensive asperity size-strengthtemperature
map taking into account the effect of contact velocity. Such a map should be
essential for various phenomena related to nanoscale contacts such as nanowire
cold welding, self-assembly of nanoparticles and adhesive nano-pillar arrays,
as well as the electrical, thermal and mechanical properties of macroscopic
interfaces