Influence of quenching rate and composition on optimal annealing temperature of Nd–Fe–B based nanocrystalline hard magnetic alloys

Abstract

A number of Nd–Fe–B based nanocrystalline hard magnetic alloys such as Nd_4–xPr_xFe₇₈B₁₈ (x = 0, 2 and 4), (Nd_0·5Pr_0·5)_xNb_1·5Fe_88·5–xB₁₀ (x = 6, 8, 10 and 12), Nd_10·5–xCo_xNb₃Fe_80·5B₆ (x = 0, 2, 4 and 6), Nd_10·5Nb_xFe_83·5–xB₆ (x = 1·5 and 3) were prepared by melt spinning and subsequently annealing. The relationships between quenching rate, composition and the annealing temperature of the alloys were investigated systematically to obtain optimal fabrication conditions. For each quenching rate and each composition, an optimal annealing temperature could be found in a range from 650 to 750°C so that the nanocrystalline magnetic phases are formed optimally leading to an enhancement of the coercivity and maximum energy product of the alloys. The variation trend of influence of quenching rate and composition on the optimal annealing temperature of the alloys is presented and discussed.

Keywords:

• Hard magnetic material
• Nanocrystalline alloy
• Nanocomposite
• Exchange spring magnet
• Metallic composite
• Rapidly quenched method

This work is supported by National Foundation for Science and Technology Development (NAFOSTED) of Vietnam under grant no. 103·02·40·09. A part of our work was performed at Key Laboratory for Electronic Materials and Devices, Institute of Materials Science.