We systematically investigate the collapse of a set of open-cell nanoporous Cu (np-Cu) materials with the same porosity and shape but different specific surface areas, during thermal annealing, by performing large-scale molecular dynamics simulations. Two mechanisms govern the collapse of np-Cu. One is direct surface premelting, facilitating the collapse of np-Cu, when the specific surface area is less than a critical value (similar to 2.38 nm(-1)). The other is recrystallization followed by surface premelting, accelerating the sloughing of ligaments and the annihilation of voids, when the cri...
