Al/Ni粉末复合材料冲击反应细观机制

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

为阐明含能结构材料冲击反应机理,开展以Al/Ni粉末复合材料为代表的含能结构材料冲击反应细观模拟研究。基于Al/Ni粉末复合材料的扫描电镜照片建立细观有限元模型,并结合Mie-Grüneisen状态方程描述Al/Ni粉末复合材料冲击压缩行为。在此基础上,基于反应扩散模型建立考虑多组分固相反应的Al/Ni粉末复合材料冲击反应细观模型,分析细观尺度上物质输运过程、冲击反应演化规律及冲击波传播特性。研究结果表明:Al/Ni粉末复合材料在冲击压缩速度(即粒子速度)为400 m/s时仅发生了微弱的化学反应,且化学反应程度随着冲击压缩速度的增大的加剧;化学反应最初发生于Al-Ni界面处,然后垂直于界面发展;冲击反应将引起材料冲击温度和压力的增高,同时对冲击波的传播起到强化作用。

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.