Finite-Size Effects in Fe-Nanowire Solid-Solid Phase Transitions: A Molecular Dynamics Approach

By means of classical molecular-dynamics simulations, we investigate solid-solid phase transitions in cylindrical iron nanowires. The interatomic potential employed has been shown to be capable of describing the martensite-austenite phase transition in iron. We investigate the dependence of the transition temperature on the wire diameter, the heating/cooling rate, and a tensile stress applied in axial direction. We observe that the phase transition temperature is inversely proportional to the wire diameter during heating and depends linearly on an applied axial tensile stress. The transition temperature becomes independent of the heating/cooling rate for the smallest rates investigated. The time the wire needs for completing the structural change is found to be independent of the diameter, the tensile loading, and the heating/cooling rate for the range of parameters considered. Finally, we find that there exists a maximum tensile stress above which the nanowire can no longer recover its initial structure after cooling.