Analysis of the Influence of Magnesium Content on the Reaction Kinetic Characteristics of Powder Combustion and Explosion Reactions in Al-Mg Alloys

This study utilizes chemical kinetics simulation technology to systematically investigate the combustion and explosion characteristics of aluminum-magnesium (Al-Mg) alloy powder under varying magnesium (Mg) contents (10, 20, 30, 40, and 50 wt%). It employs a zero-dimensional closed homogeneous reactor model in the Chemkin software to conduct numerical simulations of the combustion process of Al-xMg alloys, focusing on analyzing temperature evolution patterns, generation and consumption dynamics of key free radicals (·O, ·AlO, and ·Al2O), and evolution mechanisms of oxidation reaction pathways. Results show that Mg content significantly influences the combustion and explosion characteristics of Al-Mg alloys: the higher the Mg content, the more intense the alloy reaction. The combustion and explosion of Al-Mg alloys undergo three stages: in the initial stage, the high reactivity of Mg causes it to rapidly react with oxygen to form MgO, while Al reacts with remaining oxygen to generate intermediate products such as AlO/Al2O; subsequently, AlO/Al2O continues to react with ·O free radicals, ultimately converting to Al2O3. By comparing the reaction kinetic pathways of Al-90 wt%Mg and Al-50 wt%Mg powders, it is found that the number of reaction pathways of Al-50 wt%Mg powder is relatively fewer. Among them, the main reaction pathways of ·Al free radicals decrease from 3 to 2, and no intermediate product ·Al2O is generated. This is because during the combustion and explosion process, there is oxidative competition between Mg and Al. The entire process occurs in a closed container; due to the stronger chemical activity of Mg compared to Al, Mg preferentially reacts with oxygen in the container, leading to a reduction in the concentration of ·O free radicals in the gas phase and weakening of the Al-O reaction. The higher the Mg content, the more ·O free radicals are consumed. Therefore, when the Mg content increases to 50 wt%, ·Al can only react with the remaining ·O to form ·AlO and ·Al2O, but cannot be further oxidized to form ·AlO?. Similarly, the main reaction pathways of AlO also decrease from 4 to 3. The reaction kinetic mechanism of Al-Mg alloys reveals the microscopic changes of chemical substances during the combustion and explosion process.In addition, during the combustion and explosion of Al-Mg alloys, temperature rise is dominated by the elementary reaction between Al and ·O; the addition of Mg suppresses the Al-O reaction, thus decreasing the overall reaction temperature with increasing Mg content. These research findings provide theoretical support for the selection of Al-Mg alloys in inpowderrial production and the prevention and control of combustion and explosion accidents.