Substrate-induced liquid shearing and defect anisotropy in metallic glasses

Abstract

In amorphous alloys prepared by roller quenching, the substrate-induced shearing of the undercooled liquid results in the development of a preferred orientation of defects in the ribbon plane and elongated along the direction of substrate motion. This is supported by the authors' recent small-angle neutron scattering measurements on such materials indicating the presence of a preferred orientation of disc- or cigar-shaped density defects. The results seem to exclude the hypothesis of momentum-boundary-layer-controlled solidification. Consequences for magnetic properties are also considered.