Suppressing spinodal decomposition by adding Co into Cu-Ni-Si alloy

Spinodal decomposition is a typical type of phase transformation during aging of Cu-Ni-Si alloys which brings down the electrical conductivity; however in the present work Spinodal decomposition has been found to be suppressed by some addition of Co. Cu-2.8Ni-0.6Si and Cu-1.4Ni-1.2Co-0.6Si (wt.%) alloys have been prepared and solutioned at 900 °C, followed by aging at 400-600 °C for 0-16 h. Microstructure has been analyzed using X-ray diffraction and transmission electron microscopy. Bright field images and selected-area diffraction patterns prove that Co addition has hindered the occurrence of Spinodal decomposition. Microhardness and electrical conductivities of have been improved by adding Co. The improvement has been explained by analyzing the microstructural observation.