Inverse melting in a system with positive heats of formation

Supersaturated body-centered-cubic Fe-W solid solutions with positive heats of formation were prepared by cosputtering and mechanical alloying over a wide concentration range. Upon annealing, these solid solutions were observed to undergo amorphization in the range of 20–37 at. % W. For Fe₇₀W₃₀ and Fe₆₇W₃₃ the transformation was polymorphous, indicating an inverse melting behavior. A thermodynamic analysis of the Fe-W system, which was carried out using the calculation-of-phase-diagrams method, supported that inverse melting is energetically possible in the Fe-W system. The results demonstrate that inverse melting can also occur in systems with positive heats of amorphous phase formation.