Effects of silicon contents on the characteristics of Zr–Ti–Si–W thin film metallic glasses

In comparison with the conventional crystalline alloy films, the amorphous thin film metallic glasses (TFMGs) have been reported to exhibit unique properties, such as high strength, improved fatigue property and good corrosion resistance. Among Zr-based TFMGs, the Zr–Ti–Si–W TFMGs have not yet been explored extensively. In this work, quaternary Zr–Ti–Si–W TFMGs were fabricated on Si wafer and AISI 316L stainless steel substrates by a co-sputtering system. The target power of Si target was adjusted to achieve TFMGs with Si contents ranging from 14.3 to 19.7 at.%. For the low oxygen contained Zr–Ti–Si–W TFMGs, the hardness and corrosion resistance increased with increasing Si content. The highest hardness of 8.1 GPa was obtained for the amorphous coating containing the second highest Si content and low oxygen concentration. Highly-dosed oxygen contamination, up to around 9 to 10 at.%, would make the amorphous coating exhibit larger granular surface and columnar cross-sectional microstructure. The high oxygen content also showed detrimental effect to the hardness and the corrosion resistance of coating, due to pronounced surface crack defects. However, similar hardness and corrosion resistance enhancement by the increasing Si concentration were also observed for the high oxygen contained Zr–Ti–Si–W TFMGs. Nevertheless, sufficient adhesion property, good corrosion resistance and acceptable biocompatibility were achieved for five amorphous Zr–Ti–Si–W coatings regardless their oxygen concentration.