Nanoindentation study on shear transformation zone in a CuZrAl metallic glassy film with different thickness

• Upon nanoindentation, STZ volumes were estimated in metallic glass with various sizes.
• Both testing methods indicated that STZ volume increases with film thickness increasing.
• Substrate does not influence the present results of STZ volume in films.

Upon nanoindentation, the rate-jump method and creep test were conducted on CuZrAl metallic glassy films with thickness of 500 nm, 900 nm and 1500 nm. Based on the strain rate sensitivities (SRS) estimated by the two methods, the shear transformation zone (STZ) volumes of all the samples could be determined, respectively. Both experiment results show STZ volume increases with the film thickness increasing. In addition, substrate effect was carefully excluded on the present measurements. The variation trend of STZ volume was discussed in terms of free volume content, which was thought to be concerned with the sputtering process.