Diffusive versus displacive contact plasticity of nanoscale asperities: Temperature- and velocity-dependent strongest size

TL;DR

This paper predicts a nanoscale size for maximum contact strength influenced by temperature and velocity, driven by the competition between dislocation and surface diffusional plasticity.

Contribution

It introduces a comprehensive size-strength-temperature map for nanoscale asperities considering contact velocity effects.

Findings

Strongest contact size occurs below 10 nm radius.

Temperature significantly affects the dominant plasticity mechanism.

The map aids understanding of nanoscale contact phenomena.

Abstract

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.