A comparative study of mechanical alloying and mechanical milling of Nd8Fe88B4

A comparative study was made of structure and magnetic properties of Nd8Fe8 8B4 prepared by mechanical alloying (MA) using elemental powders as startin g materials and by mechanical milling (MM) of the alloy. X-ray diffraction (XRD and differential scanning calorimetry (DSC) combined with transmission electron microscopic (TEM) studies revealed that both milling procedures r esulted in a mixture of alpha-Fe and an amorphous phase. The thermal stabil ity of the as-milled powders produced by MA was comparable to that of the a s-milled powders produced by MM. Heat treatment of the milled powders above the crystallization temperature resulted in the formation of a nanocrystal line mixture of Nd2Fe14B and alpha-Fe, but annealed MA powders demonstrated a somewhat coarser structure in comparison with annealed MM powders. There fore, higher remanences and coercivities were obtained by MM.