Abstract
The fatigue fracture properties of the hot rolled Fe-28at.%Al intermetallic alloy with the addition of chromium and cerium were studied at elevated temperatures. The fatigue crack growth rate (υ-ΔK) curves were measured at 20, 300 and 500 °C. The alloy presents the best resistance against the fatigue crack growth at 300 °C, except for the low values of ΔK (< 24 MPa.m^1/2) for which the alloy has the lowest crack growth rate at 20 °C. Fractographic analysis carried out on fracture surfaces of ruptured specimens revealed several failure mechanisms of crack propagation. The main fatigue crack growth mechanism at all studied temperatures is transgranular cleavage. The fatigue fracture surface shows varied micromorphology. Besides transgranular cleavage, transgranular quasicleavage facets, ductile fatigue striations and brittle striations were found. In the zone of final (static) fracture, the material showed an increasing capacity of plastic deformation with increasing temperature. Fracture mechanism changed from transgranular cleavage at 20 °C to ductile dimpled fracture at 500 °C.

Key words
iron aluminides, fracture micromechanisms, fractography, fatigue crack growth

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