Temperature hysteresis of the order-disorder transition in carbon-supersaturated α-Fe

Abstract

Although many works have been devoted to the order-disorder transition in carbon-supersaturated α-Fe, all seem to have overlooked the temperature hysteresis phenomenon occurring around the critical temperature. It is shown, from a mean-field model based on the elasticity theory of point defects, that the origin of the temperature hysteresis is thermodynamic. As a consequence, both the critical temperature and carbon concentration for the order-disorder transition can be defined upon heating and cooling. The results obtained were successfully compared to molecular dynamics simulations, and are evidence that the transition is of first order and that linear elasticity is the predominant source of the thermodynamics of the Fe-C solid solutions.