Study of the unusual increase in the Curie temperature of the residual amorphous phase in nanocrystalline Fe90Zr7B2Cu1

Nanocrystalline Fe 90 Zr 7 B 2 Cu 1 with ferromagnetic BCC nanocrystals of about 10 -20 nm size embedded in a residual amorphous matrix was produced from amorphous precursor by partial crystallization. A significant increase in the Curie temperature of the residual amorphous phase (T C ) as compared to that of the amorphous precursor was found by combined bulk magnetic and Mossbauer measurements. The unusual increase of T C for alloys with different nanocrystalline fractions correlates with the quantity of the BCC phase.