In-situ microscale examination of hydrogen effect on fracture toughness: A case study on B2 and D03 ordered iron aluminides intermetallic alloys

Abstract The hydrogen embrittlement phenomenon of iron aluminides (Fe3Al and FeAl) at microscale was investigated by microcantilevers bending tests with a (1 0 0)[0 0 1] crack system. The cantilevers were loaded in-situ in an environmental scanning electron microscope under two conditions: one with water vapor to promote hydrogen uptake and the other one with high vacuum as a reference state. Fe3Al shows a distinguished cleavage fracture behavior when tested under both conditions. The microscale fracture toughness of Fe3Al was evaluated by linear elastic fracture mechanics and the basic J -integral method. FeAl, however, exhibited a stable cracking behavior and thus the fracture toughness was characterized using iterative J -integral method. For both materials, the hydrogen is found to reduce the maximum bearing load and enhance the cracking process.