Abstract
Formation, growth and structural change of grain boundary cells in a Cu-25 mass%Ni-15 mass%Co spinodal alloy on aging at 673-923 K after quenching from 1373 K were investigated by means of optical and electron microscopic observations, and X-ray measurements. This alloy decomposed spinodally during quenching. Cell formation was also observed in the as-quenched specimen. On the following aging, cells grew at a constant rate and engulfed completely the matrix before the matrix hardness reached the maximum value. Modulated structure was observed in the cells, and the amplitude and wavelength of the modulated structure increased with progress of aging. The apparent activation energies for the growth of the cell and the modulated structure in the matrix were 132 kJ/mol and 194 kJ/mol, respectively. It is considered that the cell formation in this alloy results from the preferential increases in amplitude and wavelength of the spinodal structure nearby grain boundaries owing to rapid grain boundary diffusion.
