A study of the microstructures and the effects of coating on Nd/sub 2/Fe/sub 14/B alloys

The microstructures of a range of as-cast and homogenized Nd-Fe-B-type alloys have been investigated. In the as-cast condition, all of the materials with compositions close to that of stoichiometry contain elemental free iron. Results indicate that this free iron can be removed completely from the Nd/sub 12.28/Fe/sub 81.87/B/sub 5.85/ (Nd/sub 2.1/Fe/sub 14/B) alloy by homogenization. Fine particles of the homogenized alloys and of the as-cast Nd/sub 12.94/Dy/sub 1.56/Fe/sub 77.63/Nb/sub 1.01/B/sub 6.86/ alloy (which did not contain free iron) were coated with mechanically soft metals such as copper, aluminium, and zinc, and the magnetic properties of rotary-forged compacts produced from these powders were measured. Aluminum-bonded rotary-forged compacts were also produced by mixing the fine particles of RFeB alloys with aluminum powder. The compacts produced from Nd/sub 12.94/Dy/sub 1.56/Fe/sub 77.63/Nb/sub 1.01/ B/sub 6.86/ alloy particles showed the best coercivity.<
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