To improve the ignition and combustion performance of aluminum, complementary metal is introduced into it to form binary alloy like AlÀ Mg, AlÀ Ti, AlÀ Zr and AlÀ Li. This paper mainly investigated the preparation, characterization, ignition, and combustion characteristics of AlÀ Mg alloy powder. Melt atomization technique was used to produce the spherical AlÀ Mg alloy powder containing 20 % mass content of Mg composition. The crystalline structure, morphology, element distribution, and thermal performance were characterized by XRD, TEM, SEM, EDS, and TG-DSC. Results show that the AlÀ Mg alloy had intermetallic phases of Al 12 Mg 17 and Al 3 Mg 2 , uniform element distribution , and no dense oxide shell at the surface. The laserinduced ignition and combustion characteristics of AlÀ Mg alloy powder were investigated by microscopic high-speed cinematography, photoelectric detection, and infrared thermal imaging methods. It is testified that AlÀ Mg alloy powder took intermetallic phase decomposition, then followed the two-stage combustion mode, and demonstrated gaseous emission and multiple microexplosion behavior during combustion. The ignition delay and ignition temperature were measured at elevated laser ignition power density. It is found that the temperature rise rate had a significant effect on the ignition delay.

Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion characteristics of individual aluminum particles below 10 μm. A specific in situ diagnostic experimental apparatus was first designed for directly observing the ignition and combustion behaviors of individual aluminum particles, with a submicrometer spatial resolution and a temporal resolution of tens of microseconds. Direct observation through microscopic high-speed cinematography demonstrated that, when heated by a continuous laser, individual aluminum particles thermally expanded, followed by shell rupture; the molten aluminum core overflowed and evaporated, leading to ignition and combustion. Further results showed that, when the laser power densities were gradually increased (5.88, 7.56 and 8.81 × 105 W/cm2), the durations of thermal expansion, melting and evaporation were shortened. The required time for the aluminum particles to expand to 150% of their initial diameter was shortened (34 s, 0.34 s and 0.0125 s, respectively). This study will be beneficial to further extend the investigation of other individual metal particles and reveal their combustion mechanism by direct observation.