Doctoral Thesis Defense – Jonathan Paras

An Irreversible Thermodynamic Formalism of the Electronic
Contribution to the Entropy in Metals

 We have applied an irreversible thermodynamic formalism to quantify the electronic contribution to the entropy in metals and alloys. We demonstrate the utility in our proposed approach by rationalizing the entropy of phase transitions in metal-insulator, order-disorder, and allotropic transitions with current models of the vibrational and configurational entropy. Measurements of the electronic transport properties in Cu-Ni, Fe-Ni, and Fe-Cr alloys reveal the importance of considering multicarrier transport models when interpreting electronic transport properties. We generalize our approach to include the effects of the electronic entropy on the mixing thermodynamics of these alloy systems and attempt to integrate our results with conventional thermodynamic modeling by appealing to a cluster model for their configurational entropy. Finally, our work questions the idea of “thermodynamic ideality” in these alloys. We find that the entropy of mixing shows a noticeable electronic influence even when the total entropy seems unremarkable. This suggests that the short range order (S.R.O.) of atoms plays a significant role in both the solid and molten states, even when there are no dominant intermetallic compounds in these alloys.
 
Thesis Supervisors
Antoine Allanore: Professor of Metallurgy, Massachusetts Institute of Technology
  
Thesis Committee
Juejun Hu: John F. Elliott Professor of Materials Science and Engineering, MIT
Frances Ross: Ellen Swallow Richards Professor in Materials Science and Engineering, MIT