  Tribological properties of materials play an important role in engineering
applications. Up to now, a number of experimental studies have identified
correlations between tribological parameters and the mechanical response. Using
molecular dynamics simulations, we study abrasive wear behavior via
nanoscratching of a Cu$_{64.5}$Zr$_{35.5}$ metallic glass. The evolution of the
normal and transverse forces and hardness values follows the behavior well
known for crystalline substrates. In particular, the generation of the frontal
pileup weakens the response of the material to the scratching tip and leads to
a decrease of the transverse hardness as compared to the normal hardness.
However, metallic glasses soften with increasing temperature, particularly
above the glass transition temperature thus showing a higher tendency to
structurally relax an applied stress. This plastic response is analyzed
focusing on local regions of atoms which underwent strong von-Mises strains,
since these are the basis of shear-transformation zones and shear bands. The
volume occupied by these atoms increases with temperature, but large increases
are only observed above the glass transition temperature. We quantify the
generation of plasticity by the concept of plastic efficiency, which relates
the generation of plastic volume inside the sample with the formation of
external damage, viz. the scratch groove. In comparison to nanoindentation, the
generation rate of the plastic volume during nanoscratching is significantly
temperature dependent making the glass inside more damage-tolerant at lower
temperature but more damage-susceptible at elevated temperatures.
