A first-principles study of the diffusion coefficients of alloying elements in dilute α-Ti alloys

W. W. Xu, S. L. Shang, B. C. Zhou, Y. Wang, L. J. Chen, C. P. Wang, X. J. Liu, Z. K. Liu

Research output: Contribution to journalArticle

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Abstract

Using first-principles calculations accompanied by the transition state theory and an 8-frequency model, we present a comprehensive investigation of the diffusion coefficients of substitutional alloying elements X in dilute α-Ti alloys, where X denotes Al, V, Nb, Ta, Mo, Zr, and Sn. The alloying elements Mo and Al exhibit a maximum and a minimum diffusion rate in dilute α-Ti alloys, respectively. It is found that the nearest-neighbor solute-vacancy binding energies and activation energies are roughly inversely proportional to the volume changes induced by solute atoms. There are two exceptions to this trend: Al and Mo. Besides the physical effect (i.e.; solute size), two other key factors governing solute diffusion in dilute α-Ti are clarified: the chemical bonding characteristics and vibrational features of X-Ti pairs. It verifies that the ultrafast diffusivity of Mo arises from the interactions with Ti atoms by metallic bonds and its low-frequency contributions to lattice vibration, while the more covalent bonding nature and the high-frequency contributions to the lattice vibration of Al lead to its ultraslow diffusivity. In addition, the correlation effects of diffusion coefficients are non-negligible for the large solutes Ta, Nb, and Zr, in which the direct solute-vacancy migration barriers are much smaller than the solvent-vacancy migration barriers.

Original languageEnglish (US)
Pages (from-to)16870-16881
Number of pages12
JournalPhysical Chemistry Chemical Physics
Volume18
Issue number25
DOIs
StatePublished - Jan 1 2016

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Alloying elements
alloying
solutes
diffusion coefficient
Vacancies
Lattice vibrations
lattice vibrations
diffusivity
Atoms
Binding energy
atoms
Activation energy
binding energy
activation energy
low frequencies
trends
interactions

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Xu, W. W. ; Shang, S. L. ; Zhou, B. C. ; Wang, Y. ; Chen, L. J. ; Wang, C. P. ; Liu, X. J. ; Liu, Z. K. / A first-principles study of the diffusion coefficients of alloying elements in dilute α-Ti alloys. In: Physical Chemistry Chemical Physics. 2016 ; Vol. 18, No. 25. pp. 16870-16881.
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A first-principles study of the diffusion coefficients of alloying elements in dilute α-Ti alloys. / Xu, W. W.; Shang, S. L.; Zhou, B. C.; Wang, Y.; Chen, L. J.; Wang, C. P.; Liu, X. J.; Liu, Z. K.

In: Physical Chemistry Chemical Physics, Vol. 18, No. 25, 01.01.2016, p. 16870-16881.

Research output: Contribution to journalArticle

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