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Microestrutural and magnetic properties characterization of PrFeCoB-based alloys and permanent HD sintered magnets
Autor
SILVA, M.R.M.
FIM, R.G.T.
SILVA, S.C.
CASINI, J.C.S.
TAKIISHI, H.
ENCONTRO CIENT??FICO DE F??SICA APLICADA, 7.
Resumen
The magnets were produced by powder metallurgy route, using powders obtained by hydrogenation-decrepitation method (HD). The compositions of the alloys were: Pr20FeBalB5Cu2 (33% wt.) and Pr14FebalCo16B6Nb0,1(AlSiCuGaGd)x (where x = 0,3 e 0,5) (67% wt.). The characterization of the alloys and the magnets produced have been carried out using backscattered electron microscopy (BEM), energy-dispersive X ray spectroscopy (EDXS), X ray diffraction (XRD), X ray fluorescence (XRF) and magnetic properties have been measured using a permeameter. The results revealed that the Fe-rich phase is prejudicial to magnetic properties and the improvement of the properties is due to the elimination of the Fe-rich phase by heat treatment (1343K for 20 hours). Therefore, the magnets produced by heat treated alloys presented a maximum energy product 50% higher when compared with the magnets produced by as-cast alloys. The magnet produced by Pr14FebalCo16B6Nb0,1(AlSiCuGaGd)0,5 heat treated alloy presented the best values for remanence (Br = 1.03 T), maximum energy product ((BH)m??x = 201.6 KJ.m-3) and intrinsic coercivity (iHc = 716.2 KA.m-3).