Thermodynamic investigation of the A2/B2 region of the Fe-Al system by Knudsen effusion mass spectrometry

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 34; no. 11; pp. 2409 - 2419
• Main Authors: BENCZE, L, RAJ, D. D, KATH, D, OATES, W. A, HERRMANN, J, SINGHEISER, L, HILPERT, K
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01.11.2003; Springer Nature B.V
• Subjects: Alloys; Aluminum; Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Iron; Materials science; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase diagrams of metals and alloys; Physics; Thermodynamics; Knudsen effusion; Phase diagrams; Partial pressure; Thermodynamic function; Thermodynamic activity; Mass spectroscopy; Binary systems; Aluminium; Iron; Experimental study; Thermodynamic properties
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-003-0001-8

The vaporization of Fe-Al alloys has been investigated in the temperature range of 1140 to 1600 K by Knudsen effusion mass spectrometry. Eleven different compositions were examined in the composition range between 30 and 51 at. pct Al, mostly in the B2 region of the phase diagram. The partial pressures and thermodynamic activities of both Fe and Al were evaluated: directly from the measured ion intensities for a component in both the alloy and the pure element, I+M/I+om, and also from the ion-intensity ratios of the alloy components, I+A/ /I+Fe, by means of a Gibbs-Duhem integration. Reliable partial and integral molar enthalpies and entropies of mixing have been obtained by mass spectrometry for this system for the first time. Nearly temperature-independent integral enthalpies and entropies of mixing over the wide temperature range investigated were found, with the mixing entropies being large and negative.