Al-centered icosahedral ordering in Cu₄₆Zr₄₆Al ₈ bulk metallic glass

Icosahedral short-range order, of which Al atoms are caged in the center of icosahedra with Cu and Zr atoms being the vertices, has been evidenced in the Cu₄₆Zr₄₆Al₈ glassy structure by ab initio molecular dynamics simulation. These Al-centered clusters distribute irregularly in the three-dimensional space and form a "backbone" structure of the Cu₄₆Zr₄₆Al₈ glass alloy. It is suggested that this kind of local structural feature is attributed to the requirement of efficient dense packing and the chemical affinity between Zr-Zr, Zr-Al, and Cu-Zr atoms. Our calculated results are found to be in good agreement with the experimental data.