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

Abstract

ABSTRACTThe 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°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.HighlightsThe crystallography and morphology of precipitates in a peak aged Cu–Ni–Co–Si alloy are investigated in detail at different diffraction directions. Disk-shaped (Ni, Co)2Si precipitates are confirmed through 3DAP characterization.The distribution maps of Ni, Co, and Si alloying elements are investigated. Meanwhile, the segregation of the elements in the alloy are analyzed.The strengthening mechanism and conductivity curve of Cu–1.82 Ni–1.62 Co–0.86 Si alloy (wt-%) aged at 500°C for 2 h (peak aged state) are discussed, and theoretical calculations are in excellent agreement with the experimental data.