Abstract
Fracture behaviour of two intermetallic alloys based on Fe₃ Al with different Zr content was studied. On the alloy Fe-29.5Al-2.3Cr-0.63Zr-0.2C (at%) (FA06Z), basic characterization of the microstructure by light and electron metallography was carried out. Tensile tests and fracture toughness tests were performed at 20, 200, 400 and 600 °C, respectively. The values of fracture toughness vary from 26 MPa.m^1/2 (at 20 °C) to 42 MPa.m^1/2 (at 400 °C). The fractographic analysis showed that the samples fractured at 20, 200 and 400 °C, respectively, in the tensile or fracture toughness tests exhibit transgranular cleavage fracture, while the ductile dimple fracture predominates at 600 °C. Previous fatigue experiments on the alloy Fe-31.5Al-3.5Cr-0.25Zr-0.2C (at%) (FA02Z) were completed by fatigue tests at 150 and 600 °C. The highest fatigue life and the lowest fatigue crack growth rates were found at 150 °C. The fatigue samples tested at all temperatures (20 to 600 °C) failed by transgranular cleavage fracture.

Key words
iron aluminides, Fe₃Al, tensile test, fatigue crack growth, fracture toughness, fractographic analysis

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