MAGNETIC-INTERACTIONS IN FE-CR-BASED NANOCRYSTALLINE ALLOYS

Fe66Cr8CuNb3Si13B9 nanocrystalline alloy with low fraction of the crys talline phase (15%) has been studied by means of the Mossbauer spectro metry over a wide temperature range (4.2-800 K). As a reference, the t emperature dependencies of the hyperfine parameters measured in ordere d Fe-Si alloys were used. It has been shown that the thermal evolution of the hyperfine field of the crystalline phase exhibit a kink at tem perature close to the Curie point of the amorphous matrix. This effect is explained in terms of suppression of the interphase exchange inter actions at the ferromagnetic paramagnetic phase transition of the amor phous matrix and superparamagnetic fluctuations of the magnetization i n single-domain grains. [S0163-1829(97)03041-5].