Dynamic behavior and shock-induced energy release characteristics of Ni/Al energetic structural materials prepared by cold spray additive manufacturing

Ni/Al energetic structural materials (ESMs) were widely concerned in the defense industry due to their excellent structural strength and high volumetric energy density. To evaluate the potential of Ni/Al ESMs prepared by cold spraying, the dynamic behaviors and shock-induced energy release characteristics of Ni/Al ESMs were investigated. The Ni/Al ESMs exhibited pseudo-plasticity behavior and a weak strain rate effect under dynamic loading, which differed from the brittle fracture behavior observed under quasi-static compression loading. The strain softening occurred under dynamic compression. Damage degradation was the main cause of strain softening in Ni/Al ESMs. Based on the dynamic test data, a Johnson-Cook constitutive model for Ni/Al ESMs has been developed. Further, the shock-induced energy release test showed the shock-induced reaction velocity threshold was about 740 m/s for Ni/Al ESMs. The chemical energy released per unit mass and the reaction content increased with increasing velocity. The highest reaction content (0.3656) of the Ni/Al ESMs was obtained at an impact velocity of 1638 m/s. Meanwhile, a user-defined constitutive model considering the chemical reaction in ABAQUS was used to further understand the shock-induced energy release behavior of Ni/Al ESMs. It matched the tests well. The simulation results indicated that the rate of increase in reaction content increased slowly at first, then accelerated, and finally slowed down during 740∼2500 m/s.