Thermodynamic Properties of Al-Cr-Fe Alloys. Experimental Investigation by Knudsen Effusion Mass Spectrometry

Vaporization of ternary Al-Cr-Fe and binary Al-Fe, and Cr-Fe alloys has been investigated in the temperature range 1234-1608 K by Knudsen effusion mass spectrometry (KEMS). The atoms Al, Cr, and Fe were found to be the only vapor species. Partial pressures of the elements were evaluated from the measured ion intensities and thermodynamic activities of the alloy components were determined by pressure ratio method (p/p degrees). Reliable partial and integral molar enthalpies, entropies and Gibbs energies for all the components have been obtained for the systems under investigation. The partial molar enthalpies and entropies were found to be nearly temperature independent over the wide temperature range investigated.