The role of solid solutions and intermetallic precipitates in the Al-Ni system under shock loading: a molecular dynamics study

Abstract Understanding the relationship between structure and shock response in metallic systems is essential for developing reliable materials in extreme environments. Here, molecular dynamics (MD) simulations are utilized to investigate the shock behavior of Al-Ni solid solutions, intermetallics, and composites across multiple configurations. Introducing Al solutes into a Ni matrix increased the Hugoniot Elastic Limit (HEL) and velocity of the shock wave, while reducing the spall strength and threshold for melting. The anisotropic behavior of AlNi 3 was also revealed, with changes in orientation leading to drastic differences in shock velocity and melting pressures and temperatures. AlNi 3 oriented in the [001] direction (parallel to the shock) exhibited the slowest shock velocity and required roughly three times the pressure and temperature of the [011] and [111] orientations to melt. The latter orientations showed higher spall strength. Simulations on Ni-based composites containing AlNi 3 precipitates at different volume fractions showed that strength and melting were negatively correlating with increasing the volume fraction of intermetallic precipitates. Simulations on different precipitate configurations holding the volume fraction constant confirmed that the interface played an important role. Melting was observed to initiate at the interfaces between the matrix and the precipitate. Additionally, interfaces were found to be nucleation sites for dislocations. Lastly, parameters derived from atomistic simulations were incorporated into continuum-level shock simulations to present the differences between micro- and macro-scale mechanics.