Optimization of the magnetic properties of nanocrystalline Pr5Fe77-xCrxB18 alloys

Ribbons of Pr5Fe77-xCrxB18 (x = 0, 1,2,2.5,3,4,5) alloys were produced by melt spinning and then annealed to develop, enhanced-remanence nanocrystalline magnetic material. Four different types of annealing were used in order to optimize the magnetic properties of these alloys. A conventional annealing, where the ribbons were encapsulated in quartz tubes with argon gas, was the method that led us to the best Pr2Fe14B/Fe3B nanocomposite with Cr. The annealed samples were studied by magnetic measurements, X-ray diffraction and scanning electron microscopy. The best magnetic properties are found for Pr5Fe74Cr3B18. The value for the coercive field for this composition is at least 50% higher than for the material without Cr and 40% higher than for the Nd2Fe14B/Fe3B nanocomposite with Cr. X-ray diffraction data and Curie temperature measurements showed that the main phases present in these samples are Pr2Fe14B, Fe3B and alpha -Fe. (C) 2001 Elsevier Science B.V. All rights reserved.