Mechanical properties study of a magnetron-sputtered Zr-based thin film metallic glass

Abstract

Recently metallic glass thin films represent a class of promising engineering materials for structural applications. In this work, a series of Zr-based thin film metallic glass (TFMG) were fabricated by sputtering process. The nitrogen was introduced during deposition by using a plasma emission monitoring (PEM) control system at different degrees of target poisoning rates. The structures, surface and cross-sectional morphologies, and surface roughness of thin films were explored. A nanoindenter, a scratch tester and pin-on-disk wear tests were used to evaluate the hardness, adhesion and tribological properties of thin films, respectively. The Zr-based TFMGs with nitrogen content ranging from 0 to 17.7at.% were achieved by field emission electron probe microanalyzer (FE-EPMA). The supercooled liquid region can be found when the TFMG contained less than 7.1at.% nitrogen. The nanocrystalline ZrN phase was observed as the nitrogen content was higher than 11.1at.%. The surface roughness increased with an increase of nitrogen content. On the other hand, the deposition rate decreased instead. The hardness, wear resistance and adhesion critical loads were enhanced by the addition of nitrogen. According to the Daimler Benz Rockwell-C (HRC-DB) analysis, sufficient adhesion quality was achieved for each TFMG. It can be concluded that the 13.8at.% N contained TFMG and fabricated under the Zr target poisoning rate of 50%, and having a microstructure consisting of ZrN nanograins provided a combination of high hardness, good wear resistance and excellent adhesion properties.