• Derewnicka, Daniela
• Leonowicz, Marcin
• Spyra, Marzena

Abstract

The effect of titanium addition on the structure and magnetic properties was studied for the nanocomposite Nd7Fe79–xB14Tix and Nd8Fe78–xB14Tix systems. The alloys were rapidly solidified by melt-spinning with the roll speed 20 m/s. The overquenched, amorphous ribbons were subsequently crystallization annealed for 20 min at 953–973 K. It was found that the addition of 2 and 4 at\% of Ti leads to a substantial increase of the coercivity and maximum energy product of the nanocomposite magnets while maintaining the remanence unchanged. The highest properties were obtained for the alloys containing 4 at\% of Ti. The maximum energy product of 143 kJ/m3 was achieved for the Nd8Fe74B14Ti4 alloy. The TEM studies showed substantial differences in the morphology of the alloys. The ternary alloys contain grains of various sizes of approximately 300 nm. The alloys containing 4 at\% of Ti exhibit more homogeneous structure with the crystal sizes up to 30 and 50 nm for the Nd8Fe74B14Ti4 and Nd7Fe75B14Ti4 alloys, respectively. More detailed information on the phase constitution was obtained from the Mössbauer spectroscopy. Comparison of the Ti-free and 4 at\% Ti alloys revealed that the amount of the hard magnetic Nd2Fe14B phase decreases from 84.53 to 69.88\% for the Nd7Fe79–xB14Tix system and increased from 66.60 to 82.48\% for Nd8Fe78–xB14Tix system.

Topics

• nanocomposite
• amorphous
• grain
• melt
• transmission electron microscopy
• titanium
• crystallization
• Neodymium
• coercivity
• spinning
• Mössbauer spectroscopy