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Acta Armamentarii ›› 2022, Vol. 43 ›› Issue (8): 1823-1834.

• Paper •

### Mesoscale Mechanism of the Shock Reaction of Al/Ni Powder Composites

XIONG Wei, ZHANG Xianfeng, CHEN Haihua, LIU Chuang, TAN Mengting

1. (School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China)
• Online:2022-07-18

Abstract: Mesoscale simulation of the energy release behaviors of Al/Ni powder composites is conducted to clarify the mechanism of shock reaction. A mesoscale model is established based on the Scanning Electron Microscope image of the Al/Ni composite to reveal the microstructure. The dynamic behaviors of both Al and Ni particles are described using Mie-Grüneisen equation of state. Furthermore, a shock reaction model for the solid-phase reaction between multiple components is established based on the reaction diffusion model. The shock pressure, temperature distribution and propagation of shock waves are obtained to analyze the dynamic response of the Al/Ni powder compaction. On the other hand, the evolution of reactants and reaction products are obtained to analyze the mass diffusion process, evolution of the chemical reaction, and the Al/Ni powder composite on mesoscale. The results show that the Al and Ni particles deform violently after compression, causing high shock pressure and temperature in the Al/Ni powder composites. The material Ni is transported into Al particles due to the concentration gradient and shock-induced temperature rise. The chemical reaction in the Al/Ni powder composite will be initiated by a critical condition with the particle velocity at about 400 m/s. Once the particle velocity exceeds the critical value, the reaction will be intensified with the increase of particle velocity. The above results agree well with related experimental results. The reaction product is first produced at the Al-Ni interface and then grows perpendicularly to the interface, accompanied by the consumption of reactants. Therefore, the shock reaction is initiated at and developed from the Al-Ni interface. Furthermore, the shock reaction makes additional contribution to the shock pressure and temperature, especially near the Al-Ni interface. The shock velocity of shock waves in the Al/Ni powder compaction also exceeds the value without considering the reaction.

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