Creep of Fe-18Al-4Cr alloy with zirconium addition

The creep behaviour of a rolled Fe-Al alloy containing (at. %) 17.3 Al, 3.81 Cr, 0.29 Zr and 0.13 C was examined at temperatures ranging from 550 °C to 700 °C. The applied stress dependence of the creep rate at a given temperature could be described by the power function. The values of the power n decreased with increasing temperature: n equalled nearly 8 at 550 °C and was nearly 6 at 700 °C. The apparent activation energy of creep was found to be 460 kJ/mol at 50 MPa. Three types of particles were observed: coarse particles were identified by XRD as being (Fe,Al)2Zr with cubic symmetry, whereas middle- and small-sized particles were analysed to be zirconium carbides with cubic symmetry. The sensitivity of the creep rate to the regime of heat treatment was ascribed to the growth of carbide precipitates.