Microstructure and magnetic viscosity of bulk amorphous Nd60Fe20Al5Co10B5 alloy

Abstract

The microstructure and magnetic viscosity of bulk amorphous Nd60Fe20Al5Co10B5,prepared by suction casting the molten alloy into a copper mold under an argon atmosphere, have been investigated. The results show that clusters with size 3–5 nm are found to be embedded in the amorphous matrix of as-cast bulk amorphous Nd60Fe20Al5Co10B5 alloy. The Nd60Fe20Al5Co10B5 alloy shows hard magnetic behavior at room temperature, with an intrinsic coercivity of 360 kA/m and a remanence of 69.39 mT. The magnetic viscosity of bulk amorphous Nd60Fe20Al5Co10B5 has been investigated on the major hysteresis loop, and simple logarithmic time dependence is observed. A value for the fluctuation field of 8.24 kA/m is obtained. Analysis based on a Henkel plot is used to confirm the existence of magnetic interaction among clusters. The coercivity mechanism responsible for the hard magnetic behavior of bulk amorphous Nd60Fe20Al5Co10B5 alloy is also discussed.

Combined effects of magnetic interaction and domain wall pinning on the coercivity in a bulk Nd60Fe30Al10 ferromagnet

“…It is of interest to note that, although the term amorphous is used, the common feature of the microstructure in Nd-based BAAs is the presence of clusters or nanocrystals, which vary in diameter from 1.2 nm to 20 nm, embedded in an amorphous matrix in these materials151617181920. Despite much effort, the mechanism leading to the hard magnetic behavior of Nd-based bulk amorphous alloys is still under hot debate.…”