Crystallographic features of oriented nanocrystals induced by focused-ion-beam irradiation of an amorphous alloy

Abstract

We have formed crystallographically oriented nanosized crystals (NCs) in a Ni–P amorphous alloy using focused-ion-beam (FIB) irradiation at room temperature. Transmission electron microscopy observations of the irradiated plane revealed the formation of NCs throughout the irradiated area. From a series of electron diffraction analyses, the structure of the formed NCs was determined to be face-centered cubic (fcc) of Ni and the following orientation of the formed NCs was confirmed: Irradiated plane normal ∥〈111〉fcc, and FIB direction ∥〈110〉fcc. The formed NCs consisted of two variants which have a twin relation, the twinning plane being the irradiated plane. These twin related crystals have a domainlike microstructure with an average domain size of approximately 200 nm. The elastic anisotropy of the amorphous alloy does not affect the crystallographic features of the formed NCs. The features which control the orientation of the formed NCs are discussed from crystallographic and geometrical points of view.