Nanoindentation study on shear transformation zone in a Cu[singlebond]Zr[singlebond]Al metallic glassy film with different thickness

Upon nanoindentation, the rate-jump method and creep test were conducted on Cu[singlebond]Zr[singlebond]Al metallic glassy films with thickness of 500nm, 900nm and 1500nm. 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.