CURIE-TEMPERATURE ENHANCEMENT OF ND2FE14B IN NANOCOMPOSITE EXCHANGE-SPRING ALLOYS

Curie temperatures were measured on a series of four meit-spun nanocom posite materials comprised of Nd2Fe14B and varying amounts of excess i ron ranging from similar to 0 to 27 wt%. The phase constitution and gr ain size were assessed with synchrotron X-ray diffraction; the Curie t emperatures were measured by differential thermal analysis and DC SQUI D magnetometry in the temperature range 375 K less than or equal to T less than or equal to 800 K. The Curie temperature of the 2-14-1 phase increases with increasing excess iron; thermal measurements indicate a 13 degrees enhancement over that of pure Nd2Fe,SB for 27 wt% alpha-F e, while the magnetic measurements indicate a 18 degrees enhancement f or the same composition. The results are consistent with the theoretic al predictions of Wang and Mills for analogously modeled materials.