DIFFUSION-ALLOYED ADDITIVES IN DIE-UPSET ND-FE-B MAGNETS

In general, the stoichiometry of melt-spun ribbons and subsequent hot-worked Nd-Fe-B magnets derives from the composition of the starting ingot. We have shown, however, that it is possible to introduce small amounts of powdered metals into the ribbons after the ingot has been melt spun. Many elements, when mixed with the ribbons as a fine powder and then hot pressed, have been observed to diffuse into nearby ribbons, and in some cases (Cd, Cu, Au, Ir, Mg, Ni, Pd, Pt, Ru, Ag, and Zn) the elements diffused fairly evenly throughout the Nd-Fe-B ribbon matrix. These eleven elements significantly enhanced the coercivity of die-upset magnets, with the highest coercivity observed with the addition of zinc (approximately 16 kOe).