Hard magnetic properties of melt-spun Nd-Co-Fe-B materials

The effects of cobalt substitution on the hard magnetic properties of melt-spun neodymium-iron-boron materials are reported. Samples having the starting composition Nd0.135[(CoxFe1−x)0.95B0.05 ]0.865 with x=0, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.75, and 1 were prepared by melt-spinning over a range of substrate surface velocities (i.e., quench rates) and their room-temperature magnetization characteristics measured. Choosing samples having maximal energy products, it was found that in the 0≤x≤0.5 interval the coercivity and remanence show modest overall diminution with x while the energy product declines more rapidly. Above x=0.5, the remanence, energy product, and especially the coercivity, severely deteriorate. X-ray diffraction studies indicate that for x>0.5 formation of the Nd2Fe14B-type structure is suppressed, and the samples contain progressively greater amounts of Nd2(Co,Fe)17.