Ultra-high annealing twin density in < 211 >-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 degrees 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 mu m(-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. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.