Size dependence and phase transition during melting of fcc-Fe nanoparticles: A molecular dynamics simulation

Continuous melting and cooling of isolated fcc-Fe nanoparticles with 59-9577 atoms are studied by Molecular Dynamics (MD) simulation with Sutton-Chen potential. An energy minimization process was employed to obtain the stable solid structure for simulation of melting. The energy-minimized nanoparticles show lower potential energy and radius compared with the counterparts without energy minimizing. The size dependence of melting point shows perfect linear variation with N−1/3 for particles above a limit of 113 atoms. The bulk melting temperature of 1833.3 K, which is close to the experimental data (1811 K for bcc and 1800.8 K for fcc), has been predicted by a linear relationship. Two different inner structures, including five-fold twinning and lamellar structures, have been found to be the initial stable configurations prior to melting, and both surface premelting and internal defects were verified as the origins for melting behavior.