Structure and properties of Al–Mg mechanical alloys

Mechanically alloys in the Al–Mg binary system in the range of 5–50 at.% Mg were produced for prospective use as metallic additives for propellants and explosives. Structure and composition of the alloys were characterized by x-ray diffraction microscopy (XRD) and scanning electron microscopy. The mechanical alloys consisted of a supersaturated solid solution of Mg in the aluminum phase, phase (Al12Mg17), and additional amorphous material. The strongest supersaturation of Mg in the phase (20.8%) was observed for bulk Mg concentrations up to 40%. At 30% Mg, the phase formed in quantities detectable by XRD; it became the dominating phase for higher Mg concentrations. No phase (Al3Mg2) was detected in the mechanical alloys. The observed Al solid solution generally had a lower Mg concentration than the bulk composition. Thermal stability and structural transitions were investigated by differential scanning calorimetry. Several exothermic transitions, attributed to the crystallization of and phases were observed. The present work provides the experimental basis for the development of detailed combustion and ignition models for these novel energetic materials.