The effect of Nd content on the structure and properties of melt spun Nd-rich NdFeB alloys

The influence of Nd content and cooling rate on the microstructure and extrinsic magnetic properties of nanostructured melt spun NdxFe94-xB6(x = 13-19 at%) alloys is reported. For a constant roll speed, the coercivity, H-j(c) increases rapidly between x = 13 and 15 (from similar to 0.9 to similar to 1.56 MA m(-1)) while, in spite of the nanoscaled Nd2Fe14B grains, the remanence (J(r)) decreases to below 0.8 T. Further addition of Nd up to 19 at% leads to a more gradual enhancement of H-j(c) up to similar to 1.8 MA/m and to a further decrease of J(r). A more detailed study of the effects of processing parameters was performed for the Nd 18 at% alloy. The magnetic properties are discussed briefly in terms of phase constitution and microstructure.