Heterogeneity of a Cu_(47.5)Zr_(47.5)Al_5 bulk metallic glass

摘要

Microstructural investigation of an as-cast Cu_(47.5)Zr_(47.5)Al_5 bulk metallic glass (BMG) reveals two amorphous phases formed by liquid phase separation. The morphology of the phase separated amorphous regions is spherical with 10-20 nm in size. These areas are homogeneously distributed throughout the sample. Moreover, a macroscopic heterogeneity also occurs along with the nano-scale liquid phase separation. The macroscopic heterogeneity can be distinguished from the different degree of the chemical fluctuations in the sample, and the existence of nano-scale crystals of less than 5 nm in size. Presumably, both the macroscopic heterogeneity and the nano-scale phase separation enhance branching of the shear bands during deformation in the Cu_(47.5)Zr_(47.5)Al_5 BMG.