Atomistic insights into void distribution characteristics in a NiTi cylindrical shell exposed to explosion loading

The primary objective of this study is to explore the anisotropic damage evolution mechanism of a nickel–titanium based cylindrical shell subjected to explosion loading. Atomistic simulations are performed to capture the void distribution characteristics during the formation of spallation, when the loading velocity is 1.2 km/s. Microstructure evolutions are also examined to reveal the role of shear deformation band in dynamic damage. It was discovered that voids are regularly distributed by a strip-like pattern in the [100] orientation, while in the [110] orientation, they exhibit a network-like distribution. Compared to the [100] orientation, the denser shear localizations provide more nucleation sites for voids in the [110] orientation, producing a larger number of voids. These findings demonstrate that void distribution is closely associated with shear localization. In the later stage of damage evolution, a combined effect of inertia and temperature promotes the circumferential coalescence of voids. Additionally, the void collapse was found to be present during progressive damages, which is primarily attributed to a competition between voids. In comparison, there is also a phenomenon of void collapse occurring in the sample at lower loading velocity, caused by the action of radial compression.