Nanovoid collapse mechanism in defect-free aluminum under isothermal and adiabatic conditions

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Together with void nucleation, growth, and coalescence, void collapse is a crucial component in ductile spallation. This work reports single void collapse behaviors in perfect Al under isothermal and adiabatic conditions based on molecular dynamics simulations. Two typical void collapse mechanisms, spontaneous collapse and compressive collapse, are clearly revealed. At the initial stage of void collapse, the former may be primarily attributed to the surface tension and the viscosity effects, and the latter is due to the expanding compression of a big void to a small one. The inertia effect predominates the void collapse, especially at the late stage of collapse; the temperature softening effect also conduces to the collapse under adiabatic circumstances. The average radius of the void follows an exponent decrease, and void collapse behavior is unaffected by the spallation sequence. Lastly, it is phenomenologically discovered that isothermal tension and adiabatic shock are pretty similar in void evolution.