https://doi.org/10.1140/epjb/e2014-50315-x
Regular Article
The role of vibrations in thermodynamic properties of Cu-Ni alloys
1 Institute of Informatics, Istanbul
Technical University, Maslak, 34469
Istanbul,
Turkey
2 Faculty of Engineering and Natural
Sciences, Sabanci University, Orhanli, Tuzla, 34950
Istanbul,
Turkey
3 Nanotechnology Research and
Application Center, Sabanci University, Orhanli, Tuzla, 34950
Istanbul,
Turkey
a e-mail: onat@seas.harvard.edu
Received:
18
May
2014
Received in final form:
8
September
2014
Published online:
10
November
2014
We report results of a systematic study for vibrational thermodynamic functions of Cu-Ni alloys, in the harmonic approximation, using interaction potentials based on the embedded atom method with improved optimization techniques. The vibrational density of states of the systems is calculated using real space Green’s function method. From an investigation of local force fields we found that increasing Ni concentration in the alloy substantially stiffens the force experienced by Cu atoms compared to that of Ni atoms. Our calculations also reveal that vibrational entropy change between ordered and disordered crystals of Cu-Ni is negligible. However, the mixing entropy of the phonons and electronic states is found to be negative and favors un-mixing, and thus contributes to the miscibility gap.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2014