The isothermal section of the phase diagram of Sm-Cu-Mg ternary system at 670Â K

The isothermal section of the Sm-Cu-Mg system at 670 K was studied in the 0-50 at.% Mg concentration range. The phase analysis was carried out by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), wavelength dispersive spectrometry (WDS) and X-ray powder diffraction (XRPD) techniques. The X-ray single crystal and powder analysis were used for structure investigations. Of the nine ternary phases (τ1-τ9) which were found to exist in this section are seven new phases, τ1 - Sm60.1Cu26.4Mg13.5, τ3 - Sm22.5Cu74.3Mg3.2, τ4 - SmCu4Mg, τ5 - SmCuMg, τ6 -SmCuMg2, τ7 - Sm81.2Cu10.3Mg8.5 and τ8 - Sm4Cu10Mg3, and two known phases, τ2 - Sm2Cu2Mg and τ9 - SmCu9Mg2. As the result of our investigation the crystal structures of τ2, τ4, τ5, τ6 and τ8 phases have been established. Moreover, it has been found that the solubility of Mg and Cu in Sm-Cu and Sm-Mg binary phases, respectively, is insignificant, and that the maximum solubility takes place in the case of Cu2Mg phase, which dissolves up to 5 at.% Sm.