The change in the magnetic properties of melt-spunSm2+&dgr;Fe15Ga2C2permanent magnets with variation of the Sm content &dgr; has been investigated in the range of −0.05⩽&dgr;⩽0.20. A drastic increase in the coercive field&mgr;0HCfrom 1.5 to 2.2 T at room temperature has been observed for &dgr;⩾0.1. This can be understood as an influence of the Sm-rich nonmagnetic intergranular phase, occurring due to the Sm excess. Room temperature values of the maximum energy density up to(BH)max=64.2 kJ/m3(&dgr;=0.03) can be obtained. The samples with higher Sm contents exhibit larger values of the maximum energy density at elevated temperatures(T⩾450 K).For &dgr;=0.13, a value of(BH)max=31.4 kJ/m3has been observed at 500 K. The microstructural parameters&agr;KandNeffdescribing the influence of the nonideal microstructure on the coercive field in the framework of the nucleation model were determined from the temperature dependence of the coercive field. ©1997 American Institute of Physics.