Spontaneously formed quasicrystal grains in a pure metal

Abstract

Pure metals so far have been obtained in quasicrystal (QC) forms only by templation – epitaxial growth on a QC substrate. Here, we report spontaneous formation of dodecagonal QC (DDQC) grains in pure tantalum (Ta), an early transition metal normally in a body-centered-cubic crystal structure. The DDQC grains comprise icosahedral clusters assembled in accordance with the Stampfli triangle–square tiling scheme and are formed directly from the supercooled liquid and the β-Ta phases during thermal devitrification of a Ta metallic glass in molecular dynamics simulations using a realistic quantum mechanically based interatomic potential. They co-exist with β-Ta and are retainable to and stable at room temperature, with a slightly lower configurational energy than β-Ta.