Characterization of microstructures, mechanical properties, and oxidation behavior of coherent A2 + L21 Fe-Al-Ti

Abstract

Two Fe-Al-Ti alloys with coherent αFe,Al (A2) + Fe2AlTi (L21) microstructures have been produced and the evolution of the microstructure with aging time has been studied by light optical and scanning electron microscopy and hardness measurements. The compressive flow strength, creep properties, brittle-to-ductile-transition temperatures (BDTT), and oxidation behavior of the alloys have been evaluated. The results show that the investigated alloys show good flow strength, high creep resistance, and good oxidation resistance. However, their BDDT is high compared to binary Fe-Al-based alloys and compared to other Fe-Al-Ti alloys no increase in creep resistance was achieved by generating coherent microstructures. The latter effect is due to the breakup of the coherent microstructures when the temperature varies because the compositions and consequently the volume fractions of the phases vary markedly depending on temperature.