Structurally driven asymmetric miscibility in the phase diagram of W-Ti
Journal article, 2019

© 2019 American Physical Society. Phase diagrams for multicomponent systems represent crucial information for understanding and designing materials but are very time consuming to assess experimentally. Computational modeling plays an increasingly important role in this regard but has been largely focused on systems with matching lattice structures and/or stable boundary phases. Here, using a combination of density functional theory calculations, alloy cluster expansions, free energy integration, and Monte Carlo simulations, we obtain the phase diagram of W-Ti, a system that features metastable boundary phases on both sides of the phase diagram. We find that the mixing energy on the body-centered cubic (BCC) lattice is asymmetric and negative with a minimum of about -120 meV/atom, whereas for the hexagonal closed packed (HCP) lattice the mixing energy is positive. By combining these data with a model for the vibrational free energy, we propose a revision of the W-rich end of the phase diagram with a much larger solubility of Ti in BCC-W than previous assessments. Finally, by comparison with the W-V and W-Re systems, we demonstrate how strongly asymmetric phase diagrams can arise from a subtle energy balance of stable and metastable lattice structures.

Author

Mattias Ångqvist

Chalmers, Physics, Materials and Surface Theory

Magnus Rahm

Chalmers, Physics, Materials and Surface Theory

Leili Gharaee

Chalmers, Physics, Materials and Surface Theory

Paul Erhart

Chalmers, Physics, Materials and Surface Theory

Physical Review Materials

24759953 (eISSN)

Vol. 3 7 073605

Subject Categories

Other Engineering and Technologies not elsewhere specified

Other Physics Topics

Condensed Matter Physics

DOI

10.1103/PhysRevMaterials.3.073605

More information

Latest update

10/28/2019