Structural properties of Cu-Permalloy under annealing

We have studied the structure of melt-spun copper-permalloy samples (Cu₈₀Fe₄Ni₁₆), annealed at several temperatures up to 873 K by means of EXAFS spectroscopy. The results for iron first neighbor average distance showed a slow decrease for annealing temperatures higher than 673 K. The nickel first neighbor distance had almost no change in the whole temperature range. This behavior is discussed in the light of rich iron cluster formation, and is compared with magnetic measurement results.