Magnetization performance of hard/soft Nd9.6Fe80.3Zr3.7B6.4/α-Fe magnetic nanocomposites produced by surfactant-assisted high-energy ball milling

Abstract

Neodymium iron boron (NdFeB) magnets are sintered anisotropic materials. They were commercially introduced in the early 1980s, and since have been used in different applications owing to their superior properties. Herein, we investigated the influence of 0.5 to 8 h of milling time on the morphological, structural, and magnetic performance of Nd9.6Fe80.3Zr3.7B6.4 powders produced using surfactant-assisted high-energy ball milling (SA-HEBM). The results revealed that the relationship between coercivity (Hci) and milling time had a non-monotonous character reaching a maximum value of Hci = 8.92 kOe after 1 h of milling. The effect of the volume ratio of various magnetic phases (Nd2Fe14B and α-Fe) on microstructure and magnetic properties was also reported. The highest specific saturation magnetization (σs = 120 emu g-1) was attained after 8 h of milling for powders with volume fraction: Nd2Fe14B-81 ± 2% and α-Fe-12 ± 2%. The expected value of Nd2Fe14B specific saturation magnetization was estimated (σN = 108 ± 2.5 emu g-1) using the experimental value of σs and magnetic phase volume fractions. The ratio of remanence to saturation magnetization of the Nd2Fe14B with milling time was also determined and analyzed.