Thermodynamik, Phasenumwandlung und Diffusion im System Fe-Al-Cr

• Antragsteller: Professor Dr.-Ing. Günter Borchardt; Professor Dr.-Ing. Torsten Markus; Professor Dr.-Ing. Rainer Schmid-Fetzer
• Fachliche Zuordnung: Thermodynamik und Kinetik sowie Eigenschaften der Phasen und Gefüge von Werkstoffen ; Herstellung und Eigenschaften von Funktionsmaterialien
• Förderung: Förderung von 2006 bis 2009
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 19534222

• Erstellungsjahr: 2010

Zusammenfassung der Projektergebnisse

Because of the lack of diffusion data (together with a lack of thermodynamic information) a consistent description of the obviously complex atomic transport of the constituents in the iron-rich corner of the Fe-Cr-Al system was not possible prior to this joint proposal. On the basis of the experimental and theoretical work performed during our collaborative investigations it is now possible to interpret chemical diffusion in this system on the basis of the individual mobilities of the constituents and of the respective thermodynamic driving forces. This progress was enabled by an appropriate combination of existing advanced thermodynamic modelling routes and especially developed diffusion simulation software together with tracer diffusion and chemical diffusion experiments. In order to perform computer based model calculations and assessments of phase diagrams, the precondition is the availability of a consistent thermodynamic description of the Gibbs-Energy for all constituents and occurring phases. Experimental key data of reasonable quality, on which’s base assessments are performed were practically not available in the literature prior to this project. Comprehensive measurements have been performed in the framework of this work to determine thermodynamic activities as well as enthalpies and entropies of mixing. The data address the iron rich corner of the ternary system supplemented by investigations in the corresponding binary subsystems. New experimental activity data and experimental data available in the literature form the basis of a new thermodynamic description of the system Fe-Al-Cr using the Calphad approach. This new thermodynamic description allows prediction of thermodynamic properties and phase equilibria in composition and temperature ranges for which experimental data are lacking. Future work will comprise an applied aspect and a fundamental one: Applicationwise the high mobility of aluminium (in the past of interest for the development of protective α-alumina scales only) will be of importance in designing advanced mechano-thermal transformation processing of Fe-Cr-Al base materials. From the fundamental point of view the correlation between the thermodynamic functions and the concentration dependent activation parameters of the individual mobilities will be of prime interest. Using the derived consistent set of thermodynamic data further assessments of the ternary Al-Cr-Fe system can be performed. By those, also additional needs for thermodynamic data assignment can be identified to continue to improve the quality and accuracy of the description. The thermodynamic analysis of the system Fe-Al-Cr pinpoints which experimental data are necessary to improve future thermodynamic descriptions.

Projektbezogene Publikationen (Auswahl)

• Phase behavior in the system Fe-Al. Calphad XXXVI, The Pennsylvania State University, State College, Pennsylvania, USA (2007), p98
  M.H.G. Jacobs and R. Schmid-Fetzer
  
• hermodynamics and diffusion in ternary Fe-Al-Cr alloys, Part I: Thermodynamic modeling. Intermetallics, 16, 995-1005 (2008)
  M.H.G. Jacobs, R. Schmid-Fetzer, T. Markus, V. Motalov, G. Borchardt, K.-H. Spitzer
  
• Interdiffusion in ternary Fe-Cr-Al alloys with variable molar volume, Materials at High Temperatures, 25(4), 247-255 (2008)
  D. Rohrberg, K.-H. Spitzer, L. Dörrer, P. Dawah Tankeu, M. Podsiadlo, G. Borchardt, T. Markus and R. Schmid-Fetzer
  
• Results of thermodynamic modelling and experiments in the system Fe-Al-Cr. Calphad XXXVII, Saariselkä, Finland, June 15-20 (2008), p51
  M.H.G. Jacobs, R. Schmid-Fetzer and T. Markus
  
• Thermodynamic Properties of Al-Cr-Fe Alloys - Experimental Investigation by Knudsen Effusion Mass Spectrometry, Gordon Research Conference on High Temperature Materials, Processes and Diagnostics, Waterville, ME, USA (2008)
  T. Markus, M. Motalov, D. Kath and L. Singheiser
  
• Thermodynamics and Diffusion in Ternary Fe-Al-Cr-Alloys, Diffrea 2008, On the occasion of the 80th birthday of Professor Stanislaw Mrowec, Cracow (Poland), September 2008
  A. Kulinska, M. Podsiadlo, D. Rohrberg, L. Dörrer, T. Markus, M.H.G. Jacobs, R. Schmid-Fetzer, G. Borchardt, K.-H. Spitzer
  
• Constraining thermodynamic properties of intermetallic phases in the system Fe-Al. Calphad XXXIIX, Prague, Czech Republic, May 17-22 (2009), p158
  M.H.G. Jacobs, P. Blöchl and R. Schmid-Fetzer
  
• Phase behavior and thermodynamic properties in the system Fe-Al. Calphad, 33, 170-178 (2009)
  M.H.G. Jacobs, R. Schmid-Fetzer
  
• hermodynamic properties and equation of state of fcc aluminum and bcc iron derived from a lattice vibrational method. Phys. Chem. Minerals (2010)
  M.H.G. Jacobs and R. Schmid-Fetzer
  
• „Atomic Diffusion in Fe-Cr-Al Alloys at Elevated Temperatures“, Dissertation (2010)
  A. Kulinska
  
• „Correlations between Thermodynamic Functions and Kinetic Parameters in Binary and Ternary Alloys”, Dissertation (2010)
  M. Podsiadlo