Nanoscale tunable reduction of interfacial friction on nano-patterned wear-resistant bulk metallic glass

Controllable friction and wear is desired for the structural durability and functional reliability in small-scale moving devices such as MEMS/NEMS. A critical need is to understand the fundamental mechanisms concerning interfacial friction evolution and modulation on the nano-structured surfaces, and to explore the possibility to reduce wear at the nanoscale. Here, we show a novel method to reduce friction by fabrication of nano-groove patterns on wear-resistant Zr-based bulk metallic glass of Zr52.5Cu17.9Ni14.6Al10Ti5. The tunable level of friction reduction is highly dependent on contact parameters, and the origins of a series of friction phenomena such as Amontonian behavior, friction anisotropy, logarithmic evolution and topography-induced instability are interpreted from the aspects of groove density, normal load, scan velocity, topographical direction and contact area. The exceptional anti-wear performance of glassy metal interface is attributed to the in-situ formation of a 5 nm-thick oxide layer with specific alloying components of ZrO2, CuO and Al2O3. The present findings provide key implications on the use of metallic glass as engineering materials for sustainable and efficient design of miniaturized systems.