Vibrational thermodynamics of vanadium and dilute vanadium alloys

Published

Conference Paper

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 Authors

Cited Authors

  • Delaire, O; Swan-Wood, T; Fultz, B

Published Date

  • December 1, 2005

Published In

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

Volume / Issue

  • 2 /

Start / End Page

  • 359 - 374

Citation Source

  • Scopus