The Finemet alloy prepared by the crystallizaton of an amorphous precursor is a basic model material for study of magnetic nanoparticle structures. It was shown that intensive plastic deformation localized into adiabatic shear bands causes intensive heating and structural changes in the amorphous alloy. These changes influence the magnetic properties of the amorphous precursor and the Finemet crystallization. Direct creep measurements during the crystallization of Finemet alloys were performed and the creep properties of the residual amorphous phase formed during the nanocrystallization were described. It was shown that due to relatively high temperatures the residual amorphous phase undergoes intensive structural relaxation resulting in the obvious embrittlement of these materials.