Unveiling a medium-range structural commonality of amorphous alloys

Abstract

Despite their complex atomic arrangements, previous investigations have uncovered structural features common to various metallic glasses such as dense cluster packings, local icosahedral symmetry or docosahedral clusters. While this has contributed to unraveling the nature of metallic glasses, our understanding of structural commonalities in general remains limited. In this study, we unveil a common structural feature associated with Laves phases by examining two model alloys that can adopt Laves phases. Our molecular dynamics simulations show that glasses made with sufficiently slow cooling rates contain medium-range structures resembling the core of a fivefold twinned crystal that consists of five structural units of MgCu2-type Laves structure. Since Laves phases are commonly found in Cr-, Cu-, Fe-, Mg-, Nb-, Ni-, Ti-, and Zr-based alloys, these medium-range pentagonal structures are expected to be found in a wide range of amorphous materials.