Ultra-high annealing twin density in -oriented Cu films

Abstract

We reported the fabrication of densely twinned Cu films with highly (211) texture developed from the annealing of <111>-oriented nanotwinned copper (nt-Cu) films. During the annealing at 300 °C, abnormal grain growth occurred in the nt-Cu film and resulted in a microstructure dominated by the anomalously large <211>-oriented grains. Moreover, densely-intersected annealing twin bands with <221>, <611>, and <931> orientations are embedded in the large <211> grains. The measured annealing twin density is 0.2 µm−1, which is highest among the reported values in previous literatures with similar grain size. Extensive multiple twinning process may occur during the annealing to form the unique microstructure.