Microstructure and Mechanical Properties Characterisation of Nanocrystalline Copper Films

摘要

The microstructure and mechanical properties of nanocrystalline copper with grain size ranging from 50 nm to 80 nm have been investigated. Nanocrystalline copper films were electrodeposited from an additive-free acidified copper sulphate solution at room temperature by employing constant current at different current density magnitudes between 20 and 80 mA/cm~2. Both austenitic and ferritic steel substrates with the same surface finishing conditions have been used for the deposition. The microstructure of the films has been further studied using electron microscopy techniques, and the mechanical properties using nanoindentation technique. The nanoindentation study was carried out on both the plan view and cross-sectional directions to study the isotropy characteristic of the copper film. It has been noted that both the modulus and hardness measured following the Oliver-Pharr scheme show an apparent indentation size effect tested on the cross-sectional sample.