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Vibrational thermodynamics of vanadium and dilute vanadium alloys

Publication ,  Conference
Delaire, O; Swan-Wood, T; Fultz, B
Published in: Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005
December 1, 2005

Using inelastic neutron scattering, we measured the phonon densities of states for pure vanadium and solid solutions of vanadium with 6 to 7at% of Co, Ni, Pd, Pt, at temperatures up to 1273 K for the alloys and 1673 K for pure vanadium. At room temperature, the solute atoms caused a large stiffening of the phonons, resulting in large, negative vibrational entropies of mixing. For V-6.25%Pt, the negative vibrational entropy of mixing at 293 K exceeds the conventional positive chemical entropy of mixing. At elevated temperatures, the vanadium phonon DOS shows a pronounced anharmonic behavior, with minimal softening occurring up to 1273 K. On the other hand, the alloy V-7%Co showed the more expected trend of softening between 293 K and 1273 K, in good agreement with classical thermal expansion arguments. As a result, the vibrational entropy of alloying becomes less negative with higher temperatures for this solute. The consequences of vibrational entropy on the phase-diagrams and in particular on the bcc solvus line are discussed.

Duke Scholars

Published In

Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005

Publication Date

December 1, 2005

Volume

2

Start / End Page

359 / 374
 

Citation

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Delaire, O., Swan-Wood, T., & Fultz, B. (2005). Vibrational thermodynamics of vanadium and dilute vanadium alloys. In Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005 (Vol. 2, pp. 359–374).
Delaire, O., T. Swan-Wood, and B. Fultz. “Vibrational thermodynamics of vanadium and dilute vanadium alloys.” In Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005, 2:359–74, 2005.
Delaire O, Swan-Wood T, Fultz B. Vibrational thermodynamics of vanadium and dilute vanadium alloys. In: Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005. 2005. p. 359–74.
Delaire, O., et al. “Vibrational thermodynamics of vanadium and dilute vanadium alloys.” Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005, vol. 2, 2005, pp. 359–74.
Delaire O, Swan-Wood T, Fultz B. Vibrational thermodynamics of vanadium and dilute vanadium alloys. Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005. 2005. p. 359–374.

Published In

Proceedings of an International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2005

Publication Date

December 1, 2005

Volume

2

Start / End Page

359 / 374