ND-FE-B ANISOTROPIC MAGNET POWDERS PRODUCED BY THE HDDR PROCESS

We studied the effects of many kinds of additives in Nd-Fe-B anisotropic magnet powders produced by the hydrogenation, decomposition, desorption, recombination (HDDR) process, particularly with regard to magnetic properties and microstructures. The substitution of iron with cobalt and the addition of elements such as gallium, zirconium, niobium, hafnium and tantalum was found to be very effective in inducing the magnetic anisotropy in Nd-Fe-B magnet powders. The average crystalline grain size in the magnet powder is about 0.3 mum and the shape of grains is nearly spherical. Bonded magnets made from them possess an iHc larger than 13 kOe and BHmax of about 18 MGOe. We discuss the effects of additives on the anisotropy in HDDR magnet powders.