Atomic-scale simulations of material behaviors and tribology properties for FCC and BCC metal films

The material behaviors and tribology properties of face-centered cubic (FCC) and body-centered cubic (BCC) metal films under nanocontact with a scanning probe tip are studied using molecular dynamics simulations. The results clearly show that for a given indentation depth, the required indentation force increases with atomic bonding energy. During scratching, the chips (removed atoms) pile up in front of the probe tip due to adhesion. Most of the chips behind the probe tip disappear due to elastic relaxation and elastic recovery. A slip system clearly occurs in the <110> and <111> directions for FCC and BCC metal films, respectively. A material with higher atomic bonding energy exhibits a larger normal force, a larger friction force, and a lower friction coefficient.

► The required indentation force increases with atomic bonding energy.
► During scratching, the chips pile up in front of the probe tip due to adhesion.
► Slip system occurs in the <110> and <111> directions for FCC and BCC metals, respectively.
► A material with higher atomic bonding energy exhibits a lower friction coefficient.