An investigation on sintering behavior of nanostructured Cu-10, 20 wt. % Ni alloy powders

In this research study, nano-composite powder of Cu-Ni was synthesized from precursor salts of copper and nickel sulfates through chemical co-precipitation to yield the final product of Cu-10 and 20 wt. % Ni. The chemical co-precipitation was followed by two steps of thermal and thermochemical treatments; calcination and reduction, respectively. The compounds of Cu4SO4(OH)6, Ni(OH)2 andNiOOH were identified as green precipitation which was then calcined at 850 °C for 1 h to CuO-NiO. The reduction process, by hydrogen at 700 °C for 1 h, led to Cu-Ni nanostructure powder with crystallite size of 18-33 nm. This powder was sintered at different temperatures of 1050-1200 °C for 2 h. The microstructure of synthesized powders and sintered products were evaluated using the scanning electron microscope (SEM). The value of microhardness and density, and porosity content of the sintered samples were measured. For all sintering temperatures the lowest porosity and the highest value of density were observed for Cu-10% Ni. At the sintering temperature of 1200 °C, the relative density for both samples was similar, 99.4%. Maximum value of hardness, 81.22 Vickers, was obtained for Cu-20%Ni chemical composition which was sintered at 1200 °C. Energy Dispersive Spectroscopy (EDS) which was employed for elemental mapping revealed the elemental segregation of Cu and Ni towards inter-dendrite and dendrites regions, respectively, for the samples sintered at 1200 °C.