Preparation and Crystallization of Nd2Fe14B/α-Fe Permanent Magnetic Nanomaterial by Mechanical Milling

Abstract

Nanocomposite Nd2Fe14B/α-Fe magnetic material had been prepared by mechanical milling Nd8Fe86B6 as-cast alloy in Argon and subsequent crystallization. Effect of mechanical milling and crystallization technique on its structure had been investigated by means of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Caborimetry (DSC), etc. The crystallization behavior of amorphous Nd8Fe86B6 powders had also been studied. The results showed that Nd2Fe14B grain refined quickly and the grain size of α-Fe decreased while extending milling time. After milling for 25h, grain size of α-Fe reached a constant (about 7nm). Higher temperature of complete crystallization as well as finer and more homogeneous grains resulted from longer milling time. During the process of crystallization, the total amorphous phase crystallized into four phases firstly, i.e., Nd4.4Fe77.8B17.8, Nd1.1Fe4B4, Nd2Fe14B and α-Fe. At higher temperature, final mixture was consisted of Nd2Fe14B, α-Fe and a few undecomposed Nd1.1Fe4B4 phase.