Comparison of the effect of Si and Ge presence on phase formation process, the structural and magnetic properties of Co2FeX (X=Ge,Si) Heusler compounds

In this study, the Co2FeX (X=Ge, Si) Heusler compounds with 30 valence electrons, which are made by using mechanical alloying and arc melting methods were studied. The crystallization of samples was confirmed by XRD data in both manufacturing methods. The results showed that the presence of Si than Ge in the compound played a more effective role to creation a large scale atomic ordering, and the maximum saturation magnetization is related to one of the Co2FeSi samples equal to 5.24 . However, the amount obtained is still less than the predicted value by the Slater-Pauling due to this fact that the sample isn’t single crystalline. The microstructure analysis showed that Ge has been working more effective than Si on the enhancement of crystalline nucleation in the milling process. Although the crystallite growth in the annealing process is more rapid in the presence of Ge due to the lower melting point of Ge than Si. The great coercivity observed in the milled sample of Co2FeSi compound was related to the significant anisotropy caused by the atomic ordering and also the large volume of crystallite boundary as barriers into wall movement of domains.