Relationship between the microstructure and properties of a peak aged Cu-Ni-Co-Si alloy

The microstructure and properties of a Cu-Ni-Co-Si alloy were investigated through high-resolution transmission electron microscopy and three-dimensional atom probe analysis after aging at 500 degrees C for various times. Characterisation along different diffraction directions showed that precipitate morphology was disk shaped. The concentration profiles for Ni, Co, and Si were flattened in the precipitate interiors at levels of approximately 30, 35, and 35 at.-%, respectively. The co-segregation of Co was more significant than that of Ni and Si owing to the extremely low solubility in the matrix at room temperature. Theoretical calculations excellently agreed with the experimental data, which demonstrated that solid solution scattering and the Orowan bypass mechanism were the key reinforcement mechanisms for electrical and mechanical properties, respectively.