Thermodynamic measurement of La–Fe and Y–Fe alloys by multi-Knudsen cell mass spectrometry

The activities of La and Fe in the La–Fe alloys, and those of Y and Fe in the Y–Fe alloys were determined by multi-Knudsen cell mass spectrometry. The activities of La and Fe in La–Fe alloys with La from 39.3 to 94.3 at% were determined at 1473–1623 K, measuring the ion currents of the vapor of La and Fe in equilibrium with La–Fe melts, and liquid + γFe. The activities of Y and Fe in Y–Fe alloys with Y from 15.1 to 87.8 at% were calculated at 1473–1573 K by measuring the ion currents of vapor in equilibrium with Fe17Y2 + Fe23Y6, Fe23Y6 + Fe3Y, Fe3Y + liquid, Y–Fe melts, and liquid + αY.

Research highlights▶ Activities of La and Fe in La–Fe binary system was obtained across the all composition range by measuring vapor pressure in equilibrium with the alloys. ▶ Activities of Y and Fe in Y–Fe binary system was also obtained across the all composition range. ▶ Gibbs energies of formation of intermetallic compounds in Y–Fe system were calculated.