The role of nano-scale elastic heterogeneity in mechanical and tribological behaviors of a Cu–Zr based metallic glass thin film

Despite its significance in fundamentally understanding mechanical behaviors of metallic glasses, the effect of elastic heterogeneity on plastic deformation and thereby nanotribological behavior of metallic glass thin films (MGTFs) remains an open question. By a combination of nano-scratch, nano-DMA and nanoindentation tests, we have investigated in the present work the room-temperature inhomogeneous plastic deformation behavior and nanotribological properties of Cu–Zr based MGTFs obtained by magnetron sputtering with different substrate temperatures. It is revealed that while the studied MGTF experiences a moderate rise of both hardness and Young's modulus with the elevating substrate temperature from 300 K to 473 K, its wear resistance significantly increases during the nano-scratch under a ramping load. More interestingly, through systematically studying the serration dynamics during the nano-scratch for MGTFs with different thermal history, we found that the increase of critical length scale for shear banding, which is well accompanied by the reduction of nano-scale elastic heterogeneity, tends to make shear banding more difficult in the amorphous structure, and thus enhance the wear resistance of the tested MGTFs. The current findings may provide a useful guidance to develop MGTFs with a superior mechanical and tribological properties via tuning their nanoscale elastic heterogeneity.