Fractographic analysis of the crack growth in the Fe3Al based intermetallic alloy

The fracture properties of the hot rolled Fe–28Al (at.%) intermetallic alloy with the addition of chromium and cerium were studied. The fracture toughness and the fatigue crack growth rate (da/dN−ΔK curves) were measured. Fractographic analysis carried out on fracture surfaces of ruptured specimens revealed several failure mechanisms of crack propagation. Both in static and cyclic loading the main failure mechanism is transgranular cleavage. The fatigue fracture surface shows a varied micromorphology. Besides transgranular cleavage, ductile fatigue striations and brittle striations were found. The influence of the microstructure (especially of the crystallographic orientation and the shape of grains) on the crack growth was characterized by means of electron backscattering diffraction.