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

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 M ssbauer 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.