Thermodynamic assessment of the Yb-Si system

The Yb–Si binary system was assessed using the CALPHAD method based on experimental data from the literature and a few new tensimetric measurements of the Yb activity in the liquid phase obtained by the Knudsen Effusion-Mass Spectrometry technique. A consistent thermodynamic description of the Yb–Si phases is presented: six intermediate phases (Yb5Si3, Yb5Si4, YbSi, Yb8Si11, Yb3Si5 and YbSi1.74), three solid solution phases (Yb-rich bcc and fcc, Si-rich diamond) and the liquid solution phase were considered in the assessment. The intermediate phases were treated as stoichiometric compounds, the solid solutions as ideal and the liquid solution phase by the Redlich–Kister formalism. The calculated phase diagram and thermodynamic properties are in good agreement with available experimental data.