Deformation mechanism of an electric brush-plated nanocrystalline Cu investigated by tensile testing and nanoindentation creep

Abstract

Two experimental techniques of uniaxial tensile test and nanoindentation creep were used at room temperature to investigate the deformation mechanism of an electric brush-plated 59-nm bulk Cu. Tensile tests have shown that the strengths decrease from 1000 to 635 MPa and the elongations increase from 9·9 to 15·8% at strain rates from 1 to 10^− 4 s^− 1.Nanoindentation creep tests have been performed under a maximum constant load with holding time 500 s at a depth of 2000 nm after loading at strain rates ranging from 4 × 10^− 1 to 1 × 10^− 3 s^− 1.The results have exhibited that much wider load plateau can be obtained at higher strain rate. After analysing the deformed and fracture morphologies of tensile samples and creep process in the nanoindentation, it can be concluded that dislocation motion is the dominating mode in the deformation at high strain rate, while grain boundary (GB) sliding plays an important role at low strain rate. This is the main cause why the deformed and fracture surface exhibited different morphologies and the nanoindentation creep displacement showed significant disparity.

Keywords:

• Nanocrystalline
• Strain rate
• Tensile properties
• Nanoindentation creep process
• Deformation mechanism