Sliding behavior of metallic glass Part Ⅱ. Computer simulations

摘要

Molecular dynamics (MD) calculations were used to simulate the sliding of a two-component 2D amorphous system interacting via Lennard-Jones potentials. The friction coefficient showed a transient before reaching an average steady state value. The steady state friction coefficient was observed to decrease with an increasing sliding velocity. Mixing was observed at the sliding interface. The mixed layer grew at a rate that scaled with the square root of time. A density decrease was recorded in the region adjacent to the sliding interface. This spatially corresponded to the softer layer detected experimentally near the worn surface in a Zr_(41.2)Ti_(13.8)Cu_(12.5)_Ni_(10.0)Be_(22.5) bulk metallic glass alloy after sliding. Subsurface displacement profiles produced in these simulations were similar to those observed in other material systems. The Navier-Stokes equation was used to analyze the material flow pattern, with results in agreement with data obtained from simulations. This suggests that the observed subsurface displacement profile may be a generic material flow pattern under combined compression and shear.