KAWULOK Rostislav VŠB - TU Ostrava, FMMI, katedra tváření materiálů 633

Spoluautoři OPĚLA Petr, SCHINDLER Ivo, KAWULOK Petr

Iron aluminides with 40 at.% (which corresponds approx. 24 wt. %) of aluminium are advanced structural materials that are thanks to their low density and good resistance to high temperatures suitable as replacement of expensive high alloyed steels or nickel superalloys. Their more extensive industrial application is hindered by problems at their processing, since they exhibit an extremely low formability in as-cast state. Formation of surface cracks can be prevented by use of heated forming tools. Thanks to this fact it was possible to form successfully the samples from aluminide of the type Fe-40at.%Al by uniaxial compression with use of anvils that were locally heated on the plastometer Gleeble 3800 by the system of resistance heating. Stress-strain curves were obtained for temperatures from 800 to 1200 °C and strain rates from 0.05 to 30 s-1. After the necessary smoothing of their course by an inverse method the activation energy at hot forming (236 kJ•mol-1) was calculated from the coordinates of the stress peak, which was then used for mathematical description of deformation to peak in dependence on the Zener-Hollomon parameter. We managed to develop a phenomenological model, which describes with good precision deformation resistance of the investigated alloy in dependence on temperature, strain rate and deformation, with consideration of influence of dynamic recrystallization.