Evolution of microstructures and mechanical properties of ultrahigh strength, pure electrodeposited Cu during self-annealing

Abstract

Electrodeposited Cu film shows grain growth at room temperature, referred to as self-annealing. The present work reports changes in microstructures and properties of electroplated Cu film during self-annealing. The as-deposited Cu film shows an ultrahigh strength of 876 MPa due to a high density of defects such as grain boundaries and dislocations. The tensile strength and resistivity of the electroplated copper film decrease as the time after deposition increases. The combined effect of reduction in grain boundary energy and elastic energy of dislocations could lead to the observed self-annealing in the investigated Cu film. Further, the investigated electroplated Cu film shows considerably low stacking fault energy of approximately 6 mJ/m(2), which leads to the frequent formation of twins in the self-annealed grains. (C) 2020 Elsevier B.V. All rights reserved.