Ab initio calculations of elastic properties of alloys with mechanical instability: Application to BCC Ti-V alloys

Publication date: 15 February 2018
Source:Materials & Design, Volume 140
Author(s): N.V. Skripnyak, A.V. Ponomareva, M.P. Belov, I.A. Abrikosov
Considering Ti-V alloys with the body-centered cubic crystal lattice, a system with mechanical instability for Ti-rich alloys, we calculate their elastic properties using Projector Augmented Wave method and the exact muffin‑tin orbital method in a complete interval of V concentrations. The substitutional disorder is modeled using the special quasi-random structures technique and the coherent potential approximation. The efficiency and accuracy of the simulation techniques is analyzed, and a strategy for efficient high-throughput calculations of elastic properties of disordered alloys is proposed. Dependences of the single crystal elastic moduli on V concentration and a set of mechanical characteristics of polycrystalline alloys are presented and discussed. The effect of V content on the mechanical stabilization of the bcc Ti-V alloys is investigated. In agreement with experiment, we find that titanium-rich alloys are mechanically unstable, however the alloys become mechanically stable with increasing content of V in the system. We observe a nonlinear dependence of the alloys Young's moduli in a vicinity of the mechanical stabilization and suggest that this effect can be used to design alloys with low values of the elastic moduli.

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