Sm2Fe15.5Si1.5C1.5samples with a rhombohedralTh2Zn17-type structure have been prepared by high frequency induction melting. The crystallization, crystal structure, and magnetic properties of melt-spun and annealed ribbons have been studied by means of x-ray diffraction, scanning electron microscopy, differential thermal analysis, and magnetic measurements. The results show that the as-spun ribbons consist mainly of an amorphous phase, and that they crystallize in two steps. Upon annealing at 660 °C the ribbons form a metastable phase of theTbCu7-type and an &agr;-Fe phase. Upon further annealing above 750 °C the metastable phase transforms to a 2:17-type phase coexisting with &agr;-Fe. A saturation magnetization of up to 108 emu/g with a coercivity of up to 3.5 kOe is obtained in the ribbon annealed at 660 °C for 30 min. However, the reduced remanence of the ribbon&sgr;r/&sgr;sis only 0.6 and its hysteresis loop exhibits two independent magnetic components. Additionally, the grain size of the ribbons obtained by annealing at or above 660 °C for 30 min is much larger than the single domain size. Thus, it appears that there is no significant exchange coupling between the hard and soft magnetic phases of the ribbons. ©1997 American Institute of Physics.