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We have prepared nanograin magnetic powders of SmCo7-xNix (x =0, 0.2, 0.3, 0.4, 0.5, 0.6, 1.0, 1.5, 2.0) alloys by ball milling followed by annealing at 700degC for 2 h. Samples with x=0 -1.0 show a single TbCu7-type phase (1:7) structure, and the lattice parameters a and c of this structure decrease as the Ni content increases. The Curie temperature (Tc) of the 1 :7 phase also decreases with increasing x, from 897degC at x= 0 to 771degC at x =1.5 in these samples, but it is still found that the Tc of these SmCo7-xNix samples is much higher than that of the equivalent SmCo7-xMx compounds, where M represents substituting atoms such as Ti, Zr, Cu, and Hf. Good square hysteresis loops are observed in the fine-grained samples with single 1:7 phase structure, and high room-temperature intrinsic coercivities (iHc) of larger than 1.1 T are obtained in the samples with x = 0-1.5. The temperature coefficient (beta) of the iHc was about -0.2%/degC in the temperature range of 25degC-400degC.