Statistics for Spinodal decomposition in two CuNiCr alloys has been investigated. The variations in strain amplitude, wavelength of composition modulation and yield stress increment were studied with aging time. It was found that the variation in yield stress increment with aging time followed monotonically the variations in strain amplitude and wavelength of composition modulation. It was concluded that theories which relate amplitude to yeild stress best explain the strengthening mechanism. Experimental values were found to correlate well with the theory of Kato, Mori and Schwartz. © 1987.