Highly Enhanced Energetic Kinetics and Reaction Mechanism Investigation of Hydrogenated Mg‐Al Alloys

Abstract Magnesium‐based alloy fuels and magnesium hydride (MgH 2 ) are promising candidates for fuels with high reactivity attracted numerous interests in energetic field. In this work, MgH 2 with both high combustion heat and reactivity is introduced into Magnesium‐Aluminum (Mg‐Al) alloys through solid‐state hydrogen storage technology, which achieves a well assembly of Mg, Al, and MgH 2 on a micro scale. The hydrogenation of Mg‐Al alloys is a surface‐to‐inside process, in which hydorgen (H 2 ) is sequentially complexed with α‐Mg, Al 12 Mg 17 , and Al 3 Mg 2 . Higher content of Mg and richer metallurgical interfaces in Mg‐Al alloys can contribute to a higher hydrogenation degree. In addition, distinguished from Mg‐Al alloys, the oxidization of hydrogenated Mg‐Al alloys is triggered by the dehydrogenation and oxidation of MgH 2 at ≈300 °C and 440 °C, promoting further oxidation of the internal Mg‐Al intermetallic compound and advancing the oxidation temperature ≈10–20 °C. The multi‐spectral combustion diagnostic technique further illustrates hydrogenated Mg‐Al alloys show 200–400 °C higher combustion flame temperature than raw materials, which can be ascribed to the positive feedback combustion mechanism of “combustion‐reduction‐combustion” that promotes the energetic kinetics of Mg‐Al alloy hydrides. Therefore, hydrogenated Mg‐Al alloys in this work show tremendous potential as high‐performance reactive fuels in energetic materials.