Mechanical alloying and hot sintering were used to synthesize Co \(_{2}\) Si-doped powder materials with varying boron (B) and carbon (C) ratios. The effect of B and C doping on the magnetic behavior, microwave absorption characteristics, and crystal structure of the materials was systematically investigated. All X-ray diffraction peaks corresponded to the standard card for Co \(_{2}\) Si (ICDD: 98-005-2281). The saturation magnetization (Ms) values for samples doped with 2, 4, and 8 at% B were 14.28, 19.56, and 7.36 emu/g, respectively. The Ms values for the Co \(_{2}\) Si samples doped with 2, 4, and 8 at% C were 16.66, 19.97, and 14.56 emu/g, respectively. Co \(_{2}\) Si alloys with C significantly improved their overall absorption performance. The minimum reflection loss in the C-doped Co \(_{2}\) Si alloy was \(-\) 61.88 dB, accompanied by a bandwidth of 2.38 GHz for effective absorption. Furthermore, the Co \(_{2-x}\) C \(_{x}\) Si samples (where x = 0.04, 0.08, 0.16) exhibited superior comprehensive absorption properties compared to the Co \(_{2-x}\) B \(_{x}\) Si samples.
