Influence of substrate type and film thickness on the failures of Zr-based thin-film metallic glass under nanoscratch

Abstract

Nanoscratch experiments under constant and ramp loading conditions are performed to investigate the delamination, and spallation characteristics of Zr-based thin-film metallic glass (Zr-based TFMG, Zr65Cu15Al10Ni10). TFMGs with different film thickness = 200, 500, 1000 nm are deposited over hard and soft substrates via DC magnetron sputtering process. Coefficient of friction (COF) is measured to be less about 0.03 regardless of scratch mode and maximum normal load. The critical load for thin film delamination and spallation reveals that the deformation and failure mechanism of Zr-based TFMG significantly change with film thickness and substrate type. The failure mechanism is characterized by observing the scratch grooves via optical and scanning electron microscopes (SEM). The adhesion energy between thin film and soft substrate is calculated based on Burnett and Rickerby model, and an increase in adhesion energy with interfacial layer thickness is reported.