Abstract: Limited by the surface roughness of metallic glasses, there is a lack of studies on atomic-scale friction and wear of metallic glasses. Combined the atomic force microscopy and the atomically flat Pt-based metallic glasses, the effect of load and the number of cycles on friction and wear behavior of metallic glasses are investigated in details. The results indicate that the friction coefficient of metallic glass against the tip decreases first, followed by a gradual increase by fitting the measured data into the model proposed by Bowden. This is because the friction mechanism is dominated by interfacial friction at low loads regime, in which the friction coefficient follows a decreasing trend obeying a negative power law. At high loads, however, the friction is transferred into ploughing-dominated friction mechanism, in which most of the friction energy is dissipated through plastic deformation of metallic glass and thus the friction coefficient increases with the degree of plastic deformation. Another point is that with increasing the number of cycles, both the friction coefficient and the dependence of friction coefficient on load decrease monotonously. This is attributed to the work hardening effect that takes place upon the atomic-scale deformation of metallic glass, which impedes the further plastic deformation of the materials, resulting in the decrease in friction coefficient.

Key words: metallic glass, atomic force microscope, friction and wear, normal loads, number of cycles, hardening