Experimental investigation of the phase equilibria in Co–Fe-Sm system with special attention to the effect of Fe substitution in structure and magnetic properties of intermetallic phases

Phase equilibria in the Sm–Co, Sm–Fe and Co–Fe-Sm systems were investigated in detail using DTA, X-ray diffraction, SEM and EPMA. Based on the experimental data from the present work, the liquidus and solidus projections, the isothermal section at 1000 °C and the Scheil reaction scheme for the Co–Fe-Sm system over the whole concentration range were constructed. The phase diagram of the Sm–Co system was revised. The Sm-rich region of the Sm–Fe system was studied for the first time. The stability domains of the intermetallic phases (binary phases and their extension inside ternary) were defined. Three continuous solid solutions Sm2(Co,Fe)17, Sm(Co,Fe)3 and Sm(Co,Fe)2 were found in the Co–Fe-Sm system at the solidus temperatures. In contrast to a previous analysis of the phase diagram for the system, wide homogeneity regions were revealed for the SmCo5 and Sm2Co7 phases and alternative invariant four-phase equilibria. The magnetic properties of samples containing Sm2(Co,Fe)17 phase were measured. The values of the Curie temperature and the magnetic moment of these samples were quite close to those earlier presented in the literature. •The phase diagram of the Sm–Co system was revised.•The Sm-rich region of the Sm–Fe system was studied for the first time.•Liquidus and solidus surfaces, isothermal section at 1000 °C and a Scheil diagram for Sm-Co-Fe system were constructed.•Three continuous solid solutions Sm2(Co,Fe)17, Sm(Co,Fe)3 and Sm(Co,Fe)2 were found at the solidus temperatures.•The magnetic properties of samples containing Sm2(Co,Fe)17 phase were measured.