PHASE SEPARATION IN THE Cu–Ni–Fe SYSTEM; MÖSSBAUER EFFECT EVIDENCE AGAINST DECOMPOSITION BY THE ``SPINODAL MECHANISM''

Abstract

Mössbauer spectroscopy has been used to investigate the early stages of phase separation in the Cu–Ni_.7Fe_.3 pseudobinary system. Our results indicate that new phase of composition close to the equilibrium composition is formed early in the decomposition, and grows in amount during transformation. The type of composition fluctuation predicted on the basis of the ``spinodal mechanism'' appears to be absent, and the qualitative nature of the transformation appears to be the same for temperatures above and below the spinodal.