Shock-induced melting of honeycomb-shaped Cu nanofoams: Effects of porosity

We investigate shock-induced melting in honeycomb-shaped Cu nanofoams with extensive molecular dynamics simulations. A total of ten porosities ( ϕ) are explored, ranging from 0 to 0.9 at an increment of 0.1. Upon shock compression, void collapse leads to local melting followed by supercooling at low shock strengths. Superheating occurs at ϕ≤0.1. Both supercooling of melts and superheating of solid remnants are transient, and the equilibrated shock states eventually fall on the equilibrium melting curve for partial melting. However, phase equilibrium has not been achieved on the time scale of simulations in supercooled Cu liquid (from completely melted nanofoams). The temperatures for incipient and complete melting are related to porosity via a power law, (1−ϕ)k, and approach the melting temperature at zero pressure as ϕ→1.