ELINER AFFONSO FERREIRA
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Artigo IPEN-doc 12584 The effect of milling time upon microstructures of Pr-Fe-B HD sintered magnets prepared by a low cost powder technique2006 - SOARES, E.P.; FERREIRA, E.A.; PERIGO, E.A.; TAKIISHI, H.; FARIA, R.N.Pr17Fe79B4 and Pr16Fe76B8 magnets have been produced using a combination of the hydrogen decrepitation (HD) process and a powder transfer technique. Sintered magnets have been prepared using HD powders ball milled from 9 to 36 hours. The effects of the milling stage upon microstructure have been investigated. In the Pr17Fe79B4 magnets four phases have been identified: Pr2Fe14B (Φ), Pr rich, Pr2Fe17 and Laves phase (PrFe2). In the Pr16Fe76B8 magnets three phases have been identified: Pr2Fe14B (Φ), Pr rich and Pr1+εFe4B4 (η). Good magnetic properties have been achieved in the Pr16Fe76B8 magnet produced using a fine powder milled for 18 hours (Br = 1.19 T and µ0iHc = 1.44 T). For the Pr17Fe79B4 magnet a longer milling time has been necessary to improve the magnetic properties (Br = 1.14 T and µ0iHc = 1.16T). In this case remanence and coercivity were slightly lower than that obtained in former due to the low boron content in the alloy (4 at.%).Artigo IPEN-doc 12487 The effect of milling time upon microstructures of Pr-Fe-B HD sintered magnets prepared2007 - SOARES, E.P.; FERREIRA, E.A.; PERIGO, E.A.; TAKIISHI, H.; FARIA, R.N.Artigo IPEN-doc 12483 Microstructure and magnetic properties of PrFeCoBNb sintered magnets produced from Hd and HDDR powder2007 - FERREIRA, E.A.; SILVA, S.C.; PERIGO, E.A.; FARIA, R.N.; TAKIISHI, H.Artigo IPEN-doc 13281 The effect of the HDDR process on the production of Pr-Fe-Co-B-Nb sintered magnets2008 - FERREIRA, E.A.; CASINI, J.C.S.; PERIGO, E.A.; FARIA, R.N.; TAKIISHI, H.Artigo IPEN-doc 14467 Microstructure and magnetic properties of PrFeCoBnB sintered magnets produced from HD and HDDR powders2008 - FERREIRA, E.A.; SILVA, S.C.; PERIGO, E.A.; FARIA, R.N.; TAKIISHI, H.Sintered magnets have been produced with powder obtained using the hydrogenation, disproportionation, desorption and recombination process (HDDR). The new processing procedure for the production of the sintered magnets has been adopted in an attempt to reduce the milling time. Commercial cast ingot alloys based on the compositions Pr14Fe75.9Co4B6Nb0.1 and Pr20.5FebalB5Cu2.0 have been employed in this investigation. The HDDR powder was used to produce sintered magnets using a mixture of these alloys, in very distinct proportions. Only a small amount (20 wt. %) of the copper-containing alloy has been added as a sintering aid. Standard hydrogen decrepitation (HD) magnets have also been included in this work for a comparison. The effect of a reduced milling time on the magnetic properties of the HDDR sintered magnets has been investigated. Sintering temperature and time of were kept constant for all magnets (1050ºC for 60 minutes). The microstructures of the permanent magnets have been investigated by scanning electron microscopy and energy dispersive X-ray analysis.