Thermodynamic measurement of Dy + Fe binary system by double Knudsen cell mass spectrometry

•Thermodynamic information of Dy + Fe system was measured with mass spectrometry.•The activities of Dy in Dy–Fe alloys were measured at (1273 to 1573) K.•The standard Gibbs energies of formation of intermetallic compounds were estimated.

The activities of Dy in Dy–Fe alloys with Dy concentrations ranging from (7.0 to 89) at% were determined at (1273 to 1573) K by measuring the ion current of the vapor of Dy in equilibrium with Dy–Fe melts, Dy2Fe17 + γFe, etc. The standard Gibbs energy of formation of Dy2Fe17, Dy6Fe23, DyFe3, and DyFe2 were calculated from the activities of Dy obtained from these measurements.