Shock responses of nanoporous copper with helium doping by molecular dynamics simulations

We have investigated the effects of helium (He) doping on the shock responses including shock Hugoniot, collapse mechanism of voids and the evolvement of microstructure in nanoporous copper (Cu) under shock wave loading using molecular dynamics method. We show that the compression ratios of nanoporous Cu with He doping are lower than that without He. The compression ratio reduces with the helium content increasing. The Us – up relations shows that the shock wave propagates faster in the nanoporous Cu with 10% and 20% He doping than that without He. We further show that internal helium jets form in the nanoporous Cu with He doping under high impact velocities and a shock wave in He forms during the collapse process of helium-doped voids. We reveal that the critical impact velocity to form surface fragment in nanoporous Cu without He is about 2.0 km/s. The surface damage of the nanoporous Cu is affected by He doping when the atomic ratio of He–vacancy >5%. The results show that it is more difficult to form ejecta for nanoporous Cu with He doping under high speed impact.