Molecular-dynamics study of lattice-defect-nucleated melting in metals using an embedded-atom-method potential

The high-temperature behavior of a high-angle twist grain boundary, a free surface, and planar arrays of voids of various sizes, all on the (001) plane in copper, are studied through molecular-dynamics simulation using an embedded-atom-method potential. Independently, we determine the thermodynamic melting point, Tₘ of this potential through an analysis of the free energies of a perfect crystal and the liquid phase. It is found that an ideal crystal consisting of nearly 1000 atoms may be superheated over 200 K above Tₘ while the introduction of any of the defects listed above nucleates melting at any temperature above Tₘ. We conclude that nucleation of the liquid phase at extrinsic defects is the most rapid, and therefore the dominant, mechanism of melting.