The Initial Stages of Spinodal Decomposition in a Cu-Ni-Fe Alloy Studied by Electron Microscopy

Abstract

A study has been made of the initial stages of spinodal decomposition in a Cu-Ni-Fe alloy of composition close to the centre of the miscibility gap. During ageing the average wavelength can be accurately determined from a measurement of the sideband spacing along 〈100〉 on the diffraction pattern. The results obtained show that in this alloy decomposition occurs very quickly (e.g. in <10 s ageing at 600°C (873 K)) and the average wavelength follows a coarsening law (∞ t^1/3) from the earliest time studied. The initial wavelengths found by extrapolation to zero time are of the order of 35–55 Å and vary with degree of undercooling below the spinodal in the manner predicted by theory.