Extension of Transport-Derived Electronic Entropies to the Thermochemistry of High-Temperature Solid Solutions

High-temperature quantification of the entropy of mixing in binary alloys through simulations remains an open challenge in materials thermodynamics. Recent success in using transport-property measurements to rationalize the total entropy of order-disorder and metal-insulator phase transitions in Cu₃Au and VO₂ suggest an empirical link between electronic transport properties and the electronic entropy. Measurements of the Seebeck coefficient and conductivity were conducted in solid-solution and intermetallic forming systems such as Cu-Ni and Fe-Ni at high temperature to assess the extensibility of the transport electronic entropy formalism to binary alloys. Under unipolar transport assumptions, large measured electronic entropy of mixing is reported in Cu-Ni. Similar trends were systematically observed in other high-temperature solid-solutions and their melts.