Effects of Plastic Strain on Mechanical and Electrical Conductivity Response of (100) Monocrystalline Copper

The physical characteristics of material would be influenced by its stress states. In this paper, nanoindentation experiments with a maximum load of 100 mN and strain-sensitive resistance tests were conducted on (100) monocrystalline copper with tension-induced plastic strain to investigate the influences of plastic strain on mechanical and electrical characteristics. By theoretical and experimental analysis, indentation depth, elastic modulus, recovery rate of total work, contact area, pile-up and apparent hardness of the deformed and virgin material were obtained and the corresponding investigation was compared and analyzed. The experimental results revealed that under the same conditions, tensile pre-deformed material would like to generate more penetration depth to achieve the same load during indentation. As the plastic strain increased in the uniform plastic region, both the total and elastic indentation work increased, while the recovery rate of total work, contact area, apparent hardness, and elastic modulus decreased. Meanwhile, the contribution of plastic strain to electrical resistivity was also investigated. The quantitative relation between electrical resistivity and plastic strains was extracted from experiments. The understanding of the role of plastic strain in mechanical and electrical properties of monocrystalline copper would be helpful to the application in damage detection systems and strain sensing sensor.