Structure and properties of suction-cast Pr-(Fe, Co)-(Zr, Nb)-B rod magnets

Abstract

The rod specimens were produced from Pr9Fe50 + xCo13Zr1Nb4B23 – x (x = 0, 5, 8) alloys using the suction-casting technique. Subsequent devitrification annealing of those samples resulted in the change of their phase structure and magnetic properties. For annealed specimens of all investigated compositions, the Rietveld analyses of X-ray diffractions have shown the presence of three crystalline phases: the hard magnetic Pr2Fe11.2Co2.8B, soft magnetic α-Fe, and paramagnetic Pr1 + xFe4B4, which have precipitated within the amorphous matrix. This technique allowed us to determine the weight fractions of constituent phases. Furthermore, the microstructural changes with the alloy composition were observed. Magnetic measurements of annealed rods allowed us to calculate the switching field distributions (SFD) and δM plots in order to determine the strength and character of magnetic interactions between grains of constituent phases.