Stability of medium range order in Al-based metallic glass compacted by severe plastic deformation

High pressure torsion has successfully been applied to produce low-porosity, bulk specimens from Al-based metallic glass ribbons (Al85Y8Ni5Co2, Al85Ce8Ni5Co2 and Al85Gd8Ni5Co2). The compacted disks possess higher hardness than the original glass and have substantial glass fraction with nanocrystalline precipitations. Mechanical and thermal impacts have only minor effects on the glassy structure as demonstrated by the stability of the X-ray diffraction halo positions. Unchanged halos reveal that medium range order is a key characteristic of the amorphous state.

► High pressure torsion has been applied to produce low-porosity bulk Al-based amorphous specimens.
► The compacted disks possess higher hardness than the original glass.
► Mechanical and thermal impacts have only minor effects on the glassy structure.
► Medium range order is an inherent feature of the amorphous state.