Influence of W Addition on Phase Constitution, Microstructure and Magnetic Properties of the Nanocrystalline Pr 9 Fe 65 W x B 26-x (Where: x = 2, 4, 6, 8) Alloy Ribbons

The aim of the present work was to investigate an influence of W addition on the phase constitution, microstructure and magnetic properties of the Pr Fe W B (where: x = 2, 4, 6, 8) alloy ribbons. Ribbons were obtained using the melt-spinning technique under low pressure of Ar. The as-cast samples were fully amorphous and revealed soft magnetic properties. These facts were confirmed by X-ray diffractometry, Mössbauer spectroscopy and magnetic measurements. Differential scanning calorimetry and differential thermal analysis allowed us to determine the thermal stability parameters of the amorphous phase. The Kissinger plots were constructed in order to calculate the activation energies for crystallization. Heat treatment carried out at various temperatures caused changes in the phase constitution and magnetic properties of the alloys. The phase analysis has shown the presence of the hard magnetic Pr Fe B and paramagnetic Pr Fe B phases. Additionally, for the x = 2 and x = 6 alloys, a crystallization of soft magnetic Fe B and α-Fe phases was observed. The Mössbauer spectroscopy allowed us to determine the volume fractions of constituent phases formed during annealing. The microstructure of annealed ribbons was observed using transmission electron microscopy.