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The structure and magnetic properties of Nd2Fe14BNδ -based alloys prepared by mechanical alloying have been investigated. For the Nd14Fe78B8Ny series, a large amount of NdN, α-Fe, and a small Nd2Fe14B phase are observed in x-ray diffraction patterns. With increasing Nd content, the amount of the Nd2Fe14BNδ phase increases and α-Fe decreases gradually. When x≥25 in the NdxFe92-xB8Ny systems, some amount of the N-containing, Nd-rich phase appears. Meanwhile, the content of the nitrogen in the Nd2Fe14BNδ phase decreases and, correspondingly, the Curie temperature decreases. The coercivity and the maximum magnetic energy product of this series attain maxima at x = 25. A coercivity as high as 20 kOe has been achieved. The effect of nitrogen on the formation, composition, and magnetic properties of the Nd2Fe14BNδ compound is discussed.