X-Ray Diffraction Analysis and Magnetic Properties of Pr-Fe-B HDDR Powders and Magnets

Fine magnetic powder has been produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first goal of this work involved an investigation of a range of disproportionation/desorption temperatures between 800 and 900 degrees C with the purpose of optimizing the HDDR treatment for a Pr14Fe80B6 alloy. The cast alloy was annealed at 1100 degrees C for 20 hours for homogenization. The optimum disproportionation temperature for achieving high anisotropy was 820 degrees C. The influence of the reaction temperature on the microstructure and magnetic properties of Pr14Fe80B6 HDDR powders and magnets has been shown. A second stage of this study involved the characterization, for each temperature, of the HDDR processed powder using X-ray diffraction analysis. Samples of the HDDR material have been studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy (SEM) has also been employed to reveal the morphology of the HDDR powder.