Influence of packing structure on the thermal-induced self-ignition of AlMg alloy powder

AlMg alloy powder's wide use in 3D printing and energetic materials poses major thermal self-ignition risks to energy development and safety. In this study, a custom-designed experimental system was developed to systematically investigate how various dust packing structures influence the self-ignition characteristics of AlMg alloy powder under thermal stimulation. Through spatiotemporal analysis of temperature evolution, flame propagation behavior, and visualized thermal diffusion pathways, we reveal the dominant role of packing configurations in governing heat transfer and ignition risk. The results demonstrate that stacked AlMg alloy powders exhibit a relatively low minimum self-ignition temperature, occurring at only about 310–320 °C. For 60 μm powders, the mass increase reached 187 % at 1298 °C. Moreover, finer powders exhibited multi-stage exothermic behaviors, reflecting more complex oxidation pathways. Among the tested configurations, the uniformly spread structure of 60 μm powders showed the highest heating rate, with an internal temperature rise up to 134.4 °C/min, owing to its short thermal conduction path and efficient heat transfer.This structure consistently exhibited higher (dT/dt)_max, the fastest temperature rise, and the most severe ignition hazard, with a distinct concentric flame propagation pattern. In contrast, natural packing presents an “outside-to-top, layer-by-layer combustion” behavior, while side-stacked configurations display “unidirectional lateral flame spread.” A machine learning approach was employed for clustering of key thermal parameters, enabling classification of ignition risks and predictive assessment of hazardous conditions. This work elucidates the mechanisms by which packing structures modulate thermal ignition behavior and offers data-driven insights for the safe design and management of high-energy powder materials.