The role of stable nanoparticles on improving the creep resistance of iron aluminides

Trabajo presentado en el TMS Annual Meeting Structural Aluminides for Elevated Temperatures Symposium, celebrado en New Orleans, LA (Estados Unidos), del 9 al 13 de marzo de 2008improvements, especially those that lead to large numbers of stable and fine particles. The high temperature creep behaviour has been examined at temperatures of 700°C and above in a recipitation-strengthened Fe-Al-Zr cast alloy and in an oxide dispersion-strengthened Fe-Al-yttria mechanically-alloyed material. In the first, precipitates of an Fe-Zr intermetallic form during preliminary heat treatments or during creep itself. The distribution of the precipitates is modified by the dislocations present during creep, which affects the creep behaviour. The oxide dispersion provides good strengthening up to above 800°C. At 700°C these particles create threshold stresses that lead to very low creep rates. At higher temperatures, general climb allows dislocations to overcome the small obstacles and no threshold stresses are noted