Air-resistant Mg–Fe composites for hydrogen storage produced by rheocasting followed by filing

Mg-based materials are promising for solid-state hydrogen storage due to the high theoretical capacity of MgH 2 , but their use is limited by slow kinetics and surface passivation. This work proposes a scalable casting-to-powder route that incorporates Fe as a catalytic additive with simple post-processing. An Mg–Fe ingot was produced under Ar with mechanical stirring, showing up to ∼10 wt% Fe distributed in Fe-rich domains well integrated into the Mg matrix, with nearby oxygen-rich regions. The resulting Mg–Fe filings exhibited improved hydrogen sorption kinetics, negligible incubation time, and retained reactivity after 30 days of air exposure, indicating enhanced air tolerance. Additional activation via short-time graphite-assisted milling (5 wt% graphite) further accelerated early-stage hydrogen uptake and significantly reduced the desorption onset temperature. This approach demonstrates a simple and effective strategy to produce air-tolerant Mg–Fe materials with improved hydrogen storage performance.