Al addition on the short and medium range order of CuZrAl metallic glasses

Appropriately addition of Al element can significantly enhance CuZr binary system mechanical properties and glass forming ability (GFA). In this work, the role of minor addition of Al atoms in CuZrAl metallic glasses is investigated by molecular dynamics (MD) simulation. The short and medium range structure of Cu50Zr50 and Cu45Zr50Al5 are systematically investigated from the liquid at 1600 K to amorphous solid at 100 K. Our results show that Al atoms tend to act as the centers of icosahedron (ICO), and it can remarkably increase the fraction of full ICO. More importantly, Al atoms can significantly facilitate the formation of Bergman medium range order, which accounts for the higher GFA of CuZrAl metallic glasses. The enhancement mechanism of Al addition on Bergman MRO can be explained by its adhesive effect on icosahedral clusters. •The increment of full icosahedron in Cu45Zr50Al5 compared to Cu50Zr50 is mainly provided by Al atoms.•The Al addition enhances the Bergman medium range order of Cu45Zr50Al5.•Stronger Bergman medium range order accounts for the higher glass forming ability of CuZrAl glasses.•Al atoms can serve as the adhesive of the different types ICO clusters.