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Influence of Roller Speed on Magnetic Properties and Structures of α-Fe/Nd2Fe14B Nanocomposite Magnets Prepared by Melt-spinning
Journal of Magnetics, Volume 9, Number 4, 31 Dec 2004, Pages 101-104
Abstract
The crystallization behaviours of nanocomposite made by a function of quenching rate (roller speed) were studied. The results showed that there was one step crystallization process for the alloy quenched at roller speed of 32 m/s, which could be shown as, Am (amorphouse) + α-Fe+Nd2Fe14B →α-Fe+Nd2Fe14B. For the alloy quenched at roller speed of 40 m/s, there was steps crystallization process taking place at different temperatures, which could be shown as, Am → α-Fe+Nd2Fe23B3+Nd2Fe14B+Am'→α-Fe/Nd2Fe14B. The presence of transition phase (Nd2Fe23B3 ) was harmful to get fine and uniform grain size during crystallization process. Uniform microstructures and high magnetic properties could be attained for the as-quenched alloy containing less amorphous phase and no presence of transition phase during annealing treatment. For the alloy prepared at roller speed of 32 m/s, the following properties were obtained, Br=0.904 T, iHc=801kA/m,(BH)max=122 kj/m3 and Mr/Ms= 0.6.
Keywords: Nanocomposite; Melt-spun ribbons; Annealing; Crystallization; Exchange interaction
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