Magnetic Interactions in Amorphous and Nanocrystalline Fe90Zr7Cu1B2 Alloy

Magnetic interactions and microstructure in the amorphous and nanocrystalline Fe90Zr7Cu1B2 alloy were investigated. These studies were carried out in the temperature range from 140 up to 380 K, using a Mössbauer spectrometer and completely automated set-up for measurements of magnetic properties. It has been found that the Curie temperature and quadrupole splitting decrease after annealing the sample at 573 K for 1 h (invar effect). However, this behaviour is not observed in nanocrystalline samples. In the early stages of crystallization (the volume fraction of the crystalline phase equal to about 0.06) α-Fe grains above the Curie temperature of amorphous matrix may be treated as non-interacting particles. The particle size estimated by Mössbauer spectra and magnetization curve analysis is equal to about 4 nm.