Chemical heterogeneous structure and internal record of deformation behavior in Cu-Fe-Zr metallic glasses

Abstract

Although chemical structural heterogeneities were induced into metallic glasses (MGs) to improve their ductility, the nature of the influence of the heterogeneous structure on their deformation behavior is still unclear. Here, by using microalloying elements to tailor the microstructure in Cu-Fe-Zr MGs, the formation of heterogeneous structure and the correlation between the heterogeneous structure and the deformation behavior are discussed. The results show that a honeycomb-like heterogeneous structure is formed in the (Cu0.5Fe0.5)40Zr59X1 (XNb and Ta) alloys. From a viewpoint of dynamic, the nature of the microalloying effect on the microstructure has been analysed. The deformation behavior of (Cu0.5Fe0.5)40Zr59X1 MGs with a high population of nanoscale glassy particles (NGPs) is investigated by nanoindentation and bending test. These glassy particles play an interesting role in the internal record of the local structure evolution. It was found that NGPs contiguous to shear bands (SBs) coarsen by Ostwald ripening. However, NGPs within SB would dissolve due to direct mechanical shearing and mixing. It indicates that the volume of shear transformation zone decreases obviously in the heterogeneous MGs due to the high fraction of interfaces. This work is of significance in understanding the relationship between structure and property of MGs.