Abstract:
With growing demands on the performance of materials used in explosive warheads, understanding the microstructural evolution of Al-based nanopowders under impact loading is crucial for optimizing damage-effect materials. Using molecular dynamics simulations, we systematically compared Al-Fe-Ni and Al-Fe systems to investigate shock wave propagation, phase transformations, and dislocation dynamics. Results show that increasing impact velocity significantly intensifies thermodynamic responses and accelerates atomic phase transitions. At 0.6km/s, Fe and Ni particles remain largely undeformed; however, at 1.5km/s, pressures exceed 35GPa and temperatures rise above 6000K, causing Al particle melting, deep Fe-Ni fusion, and extensive formation of OTHER structures due to strong thermo-mechanical coupling. While velocity has limited effect on dislocation spatial distribution, it markedly increases dislocation density. Ni incorporation further enhances thermal response, alters BCC phase transformation pathways, raises HCP phase content, and promotes the generation of sessile dislocations, pinning sites, and dislocation loops, thus modulating both the timing and topology of dislocation evolution. These insights provide a foundation for tailoring the design and processing of advanced energetic structural materials for warhead applications.
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