15 KB161 KB13 KB199219991998Kobe, SpomenkaMcGuiness, Paul J.Žužek Rožman, Kristinaletnik:32številka:6str. 515-518ISSN:1318-0010COBISSID:93098URN:URN:NBN:SI:doc-38OIILL4enInštitut za kovinske materiale in tehnologijeŽelezarna JeseniceŽelezarna RavneŽelezarna ŠtoreKovine zlitine tehnologijeKbk wz. 1988 Tantalkoercitivnostmagnetimagnetne lastnostimikrostrukturasamarijtantalzlitineželezoHigh coercivities in HDDR processed Sm-Fe-Ta-N magnets| Visoke koercitivnosti Sm-Fe-Ta-N magnetov dobljenih po HDDR postopku|An alloy of composition ?$Sm_{13,8}Fe_{82,2}Ta_{4,0}$? was compared with a conventional ?$Sm_{13,7}Fe_{86,3}$? material in order to assess its potential as a permanent magnet mataerial. The optimum conditions necessary to provide the highest coercivities using the HDDR process and for the HDDR process combined with milling were investigated. The coercitivities obtained after using the HDDR process and subsequent nitriding were 676,6 kA/m for the ?$Sm_{13,8}Fe_{82,2}Ta_{4,0}N_x$? and 358,2 kA/m for the ?$Sm_{13,8}Fe_{86,3}N_x$? samples. Coercivities of 1003,0 kA/m for ?$Sm_{13,8}Fe_{86,3}N_x$? and 1273,6 kA/m ?$Sm_{13,8}Fe_{82,2Ta_{4,0}N_x$? were achieved by reducing the paraticle size with milling prior to the HDDR process. Magnetic results were comparedwith the phase composition, determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The better coercivities obtained with the Ta containing sample were found to be due to the presence of a much smaller amount of ?$\alpha$?Fe, a soft magnetic phase, with the ?$TaFe_2$? phase forming in its place. The milling prior to the HDDR treatment improves the magnetic properties because of the small particle size which prevents the grains growing too laarge, with their consequent very negative effect on the coercivityPrimerjali smo zlitino sestave ?$Sm_{13,8}Fe_{82,2}Ta_{4,0}$? z že poznano zlitino sestave ?$Sm_{13,7}Fe_{86,3}$?. Želeli smo ovrednotiti potencial zlitine, z dodatko Ta, z vidika permanentnega magnetnega materiala. Poiskali smo optimalne pogoje postopka HDDR, ki so nam dali najboljše rezultate na področju magnetnih lastnosti. Koercitivnosti prahov dobljenih po tem postopku in nadaljnem nitriranju, so 676,6 kA/m za ?$Sm_{13,8}Fe_{82,2}Ta_{4,0}N_x$? in 358,2 kA/m za ?$Sm_{13,8}Fe_{86,3}N_x$?. Višje koercitivnosti 1003,0 kA/m za ?$Sm_{13,8}Fe_{86,3}N_x$? in 1273,6 kA/m za ?$Sm_{13,8}Fe_{82,2Ta_{4,0}N_x$? pa smo dosegli z mletjem materiala pred HDDR postopkom. Rezultate magnetnih lastnosti smo primerjali tudi s fazno sestavo, ki smo jo določili z elektronsko vrstično mikroskopijo (SEM) in rentgensko difrakcijo (XRD). Razliko v viški koercitivnosti sestavae s Ta gre pripisati manjši vsebnosti ?$\alpha$?Fe, ki kot mehkomagnetna faza znižuje magnetne lastnosti. ?$\alpha$?Fe s tantalom tvori ?$TaFe_2$? fazo, ki pa je paramaganetna in nima negativnega vpliva na magnetne lastnosti. Tudi predmletje materiala vpliva pozitivno na maagnetne lastnosti saj z zmanjšanjem velikosti delcev preprečimo grobo zrnatost, ki negativno vpliva na magnetne lastnostiNadaljuje se kot: Materiali in tehnologijeTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije