Hydrogen‐Assisted Fracture of Iron‐Based Fe–Ni–Al Alloys

Precipitate‐strengthened Fe‐based alloys, often referred to as body‐centered cubic superalloys, are considered as promising candidates for elevated‐temperature applications up to 700°C due to their low density, cost efficiency, and favorable mechanical performance in this temperature range. While the fundamental properties of the Fe–Ni–Al system are well studied, their behavior under hydrogen‐containing environments remains insufficiently understood, despite the high relevance of hydrogen‐rich and H 2 O‐bearing atmospheres in next‐generation energy systems. Given the intrinsic room‐temperature brittleness of Fe‐rich Fe–Ni–Al alloys and the ability of hydrogen to act as an embrittling agent, systematic investigation of hydrogen–alloy interactions is essential. This study addresses this gap by examining the influence of hydrogen on Fe‐rich compositions within the Fe–Ni–Al system, providing insights into their mechanical response after hydrogen charging. Single‐phased and two‐phased precipitate‐strengthened Fe–Ni–Al alloys are compared in terms of mechanical properties after hydrogen charging, with the two‐phase alloys showing over 50% better strength in both the reference and charged states, despite their brittle behavior. The variety of investigated charging modes allows achieving a range of hydrogen concentrations that are related to the failure stress of the alloys.