A supersaturated solid solution of Cu-44.5 at%Ni-22.5 at%Fe alloy was produced by ball milling of a pure chemical elemental mixture for 1080ks. An fee supersaturated solid solution with a grain size of about 20 nm was obtained after milling. This alloy was subsequently aged at 803, 898 and 1003 K for different times. The growth kinetics of the modulation wavelength was determined from the X-ray diffraction results and followed the Lifshitz-Slyozov-Wagner theory for a diffusion-controlled coarsening in the MA alloy after aging. The growth kinetics of composition modulation wavelength for the MA alloy was faster at 803 and 898 K than that for the same alloy composition obtained by a conventional processing and then aged at the same temperatures. The activation energy for the decomposed phase coarsening process in the MA alloy was lower man that corresponding to me conventionally-processed alloy. © 2006 The Japan Institute of Metals.