Liquidus Surface

1. Liquidus Surface Isothermal Section Re-optimization of Ti-Al-Nb Phase Diagram • The re-optimized phase diagrams resolve many controversies and show better correlations with experimental data. • Experimentally we have confirmed: • Extension of the b-phase field • The eutectic reaction (Lh+g+s) • b+g, g+s and h+g+s phase fields Ductile Ultrafine-grained g-TiAl+s-Nb2Al microstructure • We have been able to design an alloy with the following characteristics: • Single b-phase at very high temperatures (>1350˚C) • Martensitic transformation to the Orthorombic phase upon quenching • Controlled microstructural evolution upon aging to obtain ultrafine-grained g-TiAl with nanosize s-phase at the grain boundaries • Ductile behavior under indentation SEM micrograph Vickers indent at 30Kgf Computer-supported Design of High Temperature Ti-Al-Nb Alloys for Gas Turbine Applications Hans J. Seifert, University of Florida, DMR 0605702 Motivation and objective: There is a need for advanced light-weight high temperature materials for use in gas turbine engines. The objective of this project has been to combine computational and experimental studies to intelligently design alloys based on the Ti-Al-Nb-X system for high temperature applications.

2. Computer-supported Design of High Temperature Ti-Al-Nb Alloys for Gas Turbine Applications Hans J. Seifert, University of Florida, DMR 0605702 Scientific Impact In the global economy, aviation is an indispensable necessity. Therefore, well-priced fast air travel is of great importance to the economic security of this nation. The cost of fuel is a large portion of the total operating cost of airplanes. In 2007, jet fuel on average was 26.5% of the operating cost of airlines. The performance of the turbine engines is greatly enhanced by increasing the gas temperature and decreasing its weight. The findings of this project have helped to intelligently design alloys that potentially can improve the performance of jet engines. Educational Achievements • Graduate students: Orlando Rios, a minority student working on this project was selected by the Lidau Council Panel to participate at the 58th Meeting of Nobel Prize Winners in Lindau Germany between June 28 and July 4th, 2008. • Undergraduate Students: Jonah Klemm-Toole finished his undergraduate senior thesis entitled “The effect of adding Mo to a Ti-Nb-Al alloy” in May 2008. • International activity: Tabea Wilk, an undergraduate student from Germany is spending Fall 2008 and part of Spring 2009 semester at the University Florida working on this project. Presentations • D.M. Cupid, O. Fabrichnaya, O. Rios, F. Ebrahimi and H.J. Seifert, “Thermodynamic re-assessment of the Ti-Al-Nb system”, Materials Science and Engineering 2008, Nuremberg, Germany, 2008. • D.M. Cupid, O. Fabrichnaya, O. Rios, F. Ebrahimi and H.J. Seifert, “Thermodynamic re-assessment of the Ti-Al-Nb system”, Junior Euromat 2008, Lausanne, Switzerland, 2008. • D.M. Cupid, O. Fabrichnaya, O. Rios, F. Ebrahimi and H.J. Seifert, “Thermodynamic re-assessment of the Titanium-Aluminum-Niobium system”, Thermodynamics of Alloys 2008, Krakow, Poland, 2008. • H.J. Seifert, D.M. Cupid, O. Fabrichnaya, O. Rios and F. Ebrahimi, “Thermodynamic assessment of the Titanium-Aluminum-Niobium system”, CALPHAD XXXVII, Saariselkä, Finland, 2008. • H.J. Seifert, D.M. Cupid, O. Fabrichnaya, O. Rios and F. Ebrahimi, “Phase equilibria and thermodynamic assessment of the Ti-Al-Nb system”, TMS 2008, New Orleans, LA, 2008. • F. Ebrahimi M. S. Kesel, S. Goyel, O. Rios, H. J. Seifert and D. M. Cupid, “Development of TiAl-based Alloys for Elevated Temperature Applications”, TMS Annual Meeting, New Orleans, LA, March 2008. • O. Rios, S. Goyel, M. S. Kesler, H. J. Seifert, D. M. Cupid and F. Ebrahimi, “Examination of the Transformation Path in Ti-Al-Nb Alloys”, TMS Annual Meeting, New Orleans, LA, March 2008.