Synergetic energetic kinetics of Mg-Zn alloys and pyrotechnics

Zn has been incorporated into Mg via centrifugal atomization in this work. The prepared Mg-Zn alloys have been characterized via SEM/EDS and XRD. The thermal behavior and combustion of Mg-Zn alloys have been tested by TG/DSC and laser ignition. Then, Mg-Zn alloys have been applied in pyrotechnics with PTFE as the oxidizer, followed by measuring the reactivity and ignition delay. Mg-5%Zn and Mg-10%Zn alloys consisting of α-Mg and eutectic phase (α-Mg and MgZn₂) in a high degree of sphericity with evenly distributed Zn were obtained. Thermal behavior characterization indicates that the oxidation of Mg-Zn alloys initiates ∼50 °C earlier than Mg along with a higher oxidation rate, which could be attributed to the lower melting point of MgZn₂ and Zn. In addition, the oxidation rate of Mg-Zn alloys is also higher than Mg that is the result of significantly lower apparent activation energy of Mg-Zn alloys than Mg. Due to the great discrepancy of melting and evaporation point between Mg, MgZn₂, and Zn, a visible microexplosion phenomenon has been observed during the combustion process of Mg-Zn alloys. Then, Mg-Zn alloys have been applied as the fuel to replace Mg in Mg/PTFE pyrotechnics. The ignition delay of Mg-Zn/PTEE composites is shorter than that of Mg/PTFE, which is due to the easier oxidization initiation of Mg-Zn alloys compared to Mg. Besides, the lower melting and evaporation points of MgZn₂ and Zn than Mg can accelerate the combustion of Mg-Zn alloys, leading to the improved peak pressure and reaction rate of Mg-Zn/PTEE. Thus, the lower apparent activation energy of Mg-Zn alloys and the lower melting point of MgZn₂ and Zn could promote the energetic kinetics of Mg-Zn alloys synergistically. Above all, the prepared Mg-Zn alloys in this study are ambitious candidates in pyrotechnics for controllable ignition and reactivity kinetics.