Experimental investigation and thermodynamic modeling of the Gd-Si system

The Gd-Si system has been investigated via experiments and thermodynamic modeling. In the experimental part, alloys were prepared by arc melting pure Gd and Si slugs and annealing at high temperature. The annealed alloys were then investigated by thermal analysis, X-ray diffraction and scanning electron microscopy. Except for the compound with AlB2 structure, the existence of all other compounds was confirmed. In our study, instead of Gd2Si3, the compound with AlB2 structure was found to be Gd3Si5. Although most of the reported invariant reaction temperatures are in good agreement with the present data, the convex liquidus in the composition range of 55-65 at.% Si was not found. The available phase equilibrium and thermodynamic data for the Gd-Si system were used in optimization of thermodynamic parameters by WinPhad software. The calculated phase equilibria and thermodynamic properties were compared to the corresponding experimental data and good agreement was found.