Magnetic interactions in amorphous and nanocrystalline Fe90Zr7Cu1B2 alloy

Magnetic interactions and microstructure in the amorphous and nanocrystalline Fe90Zr7-Cu1B2 alloy were investigated. These studies were carried out in the temperature range from 140 up to 380 K, using a Mossbauer spectrometer and completely automated set-up for measurements of magnetic properties. It has bren 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) alpha -Fe grains above the Curie temperature of amorphous matrix may be treated as non-interacting particles. The particle size estimated by Mossbauer spectra and magnetization curve analysis is equal to about 4 nm.