Mechanical behavior of a Zr-based bulk metallic glass and its composite at cryogenic temperatures

Abstract

The mechanical behavior of Zr-Cu-Al bulk metallic glasses (BMGs) and in situ Ta-particle-containing composites (BMGCs) was investigated at 77 K. Their strengths increased significantly whereas the plastic strains remained at comparable levels, when compared to that at 298 K. The interaction between shear bands and particles shows that shear extension in particles has limited penetration, and shear bands build up around particles. Pair distribution functions (PDFs), which carried out at cryogenic and ambient temperatures on the as-cast Zr-Cu-Al bulk metallic glasses, were studied, and simulations with reverse Monte Carlo (RMC) were performed by combining icosahedral and cubic structures as the initial structures. Based on the studies of the pair distribution functions and the Reverse Monte Carlo simulations, the concept of free volume was defined—spaces between clusters with longer bond lengths of atom pairs; the structural model of BMGs was proposed—the strongly bonded clusters correlated with each other and separated by free volume. An attempt has been made to connect the relationship between amorphous structures and their mechanical properties.