Effect of super heat treatment on crystallization behavior and magnetic properties of Nd_4.5Fe₇₇B_18.5 nanocomposites

盛洪超¹，曾燮榕^2,3，邹继兆^2,3，谢盛辉¹

1. School of Materials Science and Engineering,Northwestern Polytechnical University2. College of Materials Science and Engineering,Shenzhen University3. Shenzhen Key Laboratory of Special Functional Materials

摘 要：Melt-spun Nd4.5Fe77B18.5 ribbons were prepared under various superheat temperatures.The microstructure characteristics,crystallization behavior,and subsequent magnetic properties of Fe3B/Nd2Fe14B nanocomposite magnets were investigated using X-ray diffraction,differential thermal analysis,and vibrating sample magnetometry.It was shown that melt spinning at different quenching temperatures caused the as-quenched ribbons to have distinctive crystallization behavior.Depending on superheat temperature,phase transformation of the ribbons during annealing may take place in one of the following sequences:（1） amorphous phase（Am）→Am’+Fe3B→Fe3B+ Nd2Fe23B3→ Fe3B+Nd2Fe14B,or（2） amorphous phase（Am）→Am’+Fe3B→Fe3B+Nd2Fe14B.For the latter,the ribbon after optimal annealing exhibited single-phase magnetic behavior.In the first case,magnetic properties of the optimally heat treated ribbons deteriorated and an apparent kink could be seen along the demagnetization curves near the zero field.

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