A comparative thermomagnetic study of melt-spun Nd-Fe-B alloys with different Nd content

Abstract

Changes in the phase composition and magnetic properties of three types of commercial Nd-Fe-B alloys with different Nd content - low (10-12 wt%), near stoichiometric (21-25 wt%) and rich (26-29 wt%) caused by thermomagnetic analysis (TM) were observed in regard to optimal magnetic state. Phase compositions of investigated alloys before and after TM measurement up to 800°C were compared using 57Fe Mössbauer spectroscopy and X-Ray analysis. The TM measurements decompose all three materials and the main products of decomposition process α-Fe and Fe2B phase. Observed changes in structure and phase composition had direct influence on magnetic properties. Loss of magnetic properties induced by thermal decomposition is clearly illustrated on corresponding SQUID hysteresis loops.

Istraživane su promene faznog sastava i magnetnih svojstava u odnosu na optimalno magnetno stanje za tri tipa komercijalnih Nd-Fe-B legura sa različitim sadržajem neodijuma - niskim (10-12 mas %), bliskim stehiometrijskom (21-25 mas %) i visokim (26-29 mas %), prouzrokovanih termomagnetnim (TM) merenjima. Fazni sastavi istraživanih legura pre i posle TM merenja do 800°C su poređeni koršćenjem 57Fe Mössbauer spektroskopske fazne analize i rendgensko-difraktometrijske analize. Usled termomagnetnih merenja dolazi do dekompozicije sva tri istraživana materijala i kao osnovni produkti dekompozicije nastaju α-Fe i Fe2B faze. Posmatrane promene u strukturi i faznom sastavu imaju direktan uticaj na magnetna svojstva. Gubitak magnetnih svojstava nastao usled termičke dekompozicije je jasno ilustrovan odgovarajućim SQUID histerezisnim petljama.