A fundamental study on ignition dynamics and combustion characteristics of Al–Mg alloys with varied magnesium content

Due to their exceptional combustion properties, highly reactive Al–Mg alloys exhibit significant technological applicability in military and aerospace fields. This study systematically investigates the mechanisms of thermal oxidation, ignition, and combustion in Al–Mg alloys with Mg contents ranging from 0 % to 50 %, employing thermogravimetric analysis and laser ignition tests. Furthermore, based on temperature-dependent thermophysical parameters and an oxidizer diffusion model, a kinetic model for Al–Mg alloy ignition was established, elucidating the effects of Mg content on ignition delay time and oxide formation. Simulation outcomes exhibited a 1.25∼7.46 % deviation relative to experimentally determined ignition delay times, confirming the model's accuracy. The comprehensive results demonstrate that, compared to raw Al, Mg significantly enhances the overall chemical reaction heat of the alloy through its surface reaction heat and gas-phase reaction heat, thereby accelerating oxidation kinetics and enhancing energy release efficiency. Moreover, Mg effectively disrupts the dense oxide shell and utilizes jetting and boiling phenomena driven by the significant boiling point disparity between Mg and Al, consequently improving combustion efficiency. Increasing Mg content also accelerates alloy heating and melting rates, facilitating heterogeneous chemical reactions and thermal release, which reduces the ignition threshold and extends the reaction scope. These insights establish a theoretical foundation for applying Al–Mg alloys in high-performance fuels and energy-regulating materials.