Microstructural evolution of Fe{sub 3}B/Nd{sub 2}Fe{sub 14}B nanocomposite magnets microalloyed with Cu and Nb
The microalloying effect of Cu and Nb on the microstructure and magnetic properties of an Fe{sub 3}B Nd{sub 2}Fe{sub 14}B nanocomposite permanent magnet has been studied by transmission electron microscopy (TEM) and atom probe field ion microscopy (APFIM). Additions of Cu are effective in refining the nanocomposite microstructure and the temperature range of the heat treatment to optimize the hard magnetic properties is significantly extended compared with that of the ternary alloy. Combined addition of Cu and Nb is further effective in reducing the grain size. Optimum magnetic properties obtained by annealing a melt-spun Nd{sub 4.5}Fe{sub 75.8}B{sub 18.5}Cu{sub 0.2}Nb{sub 1} amorphous ribbon at 660 C for 6 min are B{sub r} = 1.25 T, H{sub cJ} = 273 kA/m and (BH){sub max} = 125 kJ/m{sup 3}. The soft magnetic Fe{sub 23}B{sub 6} phase coexists with the Fe{sub 3}B and Nd{sub 2}Fe{sub 14}B phases in the optimum microstructure of the Cu and Nb containing quinternary alloy. Three-dimensional atom probe (3DAP) results show that the finer microstructure is due to the formation of a high number density of Cu clusters prior to the crystallization reaction, which promote the nucleation of the Fe{sub 3}B phase. The Nb atoms appear to induce the formation of the Fe{sub 23}B{sub 6} phase when the remaining amorphous phase is crystallized.
- Research Organization:
- National Research Inst. for Metals, Tsukuba (JP)
- OSTI ID:
- 20005415
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 18 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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